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PERLDIAG(1pm)          Perl Programmers Reference Guide          PERLDIAG(1pm)




NAME

       perldiag - various Perl diagnostics


DESCRIPTION

       These messages are classified as follows (listed in increasing order of
       desperation):

           (W) A warning (optional).
           (D) A deprecation (enabled by default).
           (S) A severe warning (enabled by default).
           (F) A fatal error (trappable).
           (P) An internal error you should never see (trappable).
           (X) A very fatal error (nontrappable).
           (A) An alien error message (not generated by Perl).

       The majority of messages from the first three classifications above (W,
       D & S) can be controlled using the "warnings" pragma.

       If a message can be controlled by the "warnings" pragma, its warning
       category is included with the classification letter in the description
       below.  E.g. "(W closed)" means a warning in the "closed" category.

       Optional warnings are enabled by using the "warnings" pragma or the -w
       and -W switches.  Warnings may be captured by setting $SIG{__WARN__} to
       a reference to a routine that will be called on each warning instead of
       printing it.  See perlvar.

       Severe warnings are always enabled, unless they are explicitly disabled
       with the "warnings" pragma or the -X switch.

       Trappable errors may be trapped using the eval operator.  See "eval" in
       perlfunc.  In almost all cases, warnings may be selectively disabled or
       promoted to fatal errors using the "warnings" pragma.  See warnings.

       The messages are in alphabetical order, without regard to upper or
       lower-case.  Some of these messages are generic.  Spots that vary are
       denoted with a %s or other printf-style escape.  These escapes are
       ignored by the alphabetical order, as are all characters other than
       letters.  To look up your message, just ignore anything that is not a
       letter.

       accept() on closed socket %s
           (W closed) You tried to do an accept on a closed socket.  Did you
           forget to check the return value of your socket() call?  See
           "accept" in perlfunc.

       Aliasing via reference is experimental
           (S experimental::refaliasing) This warning is emitted if you use a
           reference constructor on the left-hand side of an assignment to
           alias one variable to another.  Simply suppress the warning if you
           want to use the feature, but know that in doing so you are taking
           the risk of using an experimental feature which may change or be
           removed in a future Perl version:

               no warnings "experimental::refaliasing";
               use feature "refaliasing";
               \$x = \$y;

       Allocation too large: %x
           (X) You can't allocate more than 64K on an MS-DOS machine.

       '%c' allowed only after types %s in %s
           (F) The modifiers '!', '<' and '>' are allowed in pack() or
           unpack() only after certain types.  See "pack" in perlfunc.

       alpha->numify() is lossy
           (W numeric) An alpha version can not be numified without losing
           information.

       Ambiguous call resolved as CORE::%s(), qualify as such or use &
           (W ambiguous) A subroutine you have declared has the same name as a
           Perl keyword, and you have used the name without qualification for
           calling one or the other.  Perl decided to call the builtin because
           the subroutine is not imported.

           To force interpretation as a subroutine call, either put an
           ampersand before the subroutine name, or qualify the name with its
           package.  Alternatively, you can import the subroutine (or pretend
           that it's imported with the "use subs" pragma).

           To silently interpret it as the Perl operator, use the "CORE::"
           prefix on the operator (e.g. "CORE::log($x)") or declare the
           subroutine to be an object method (see "Subroutine Attributes" in
           perlsub or attributes).

       Ambiguous range in transliteration operator
           (F) You wrote something like "tr/a-z-0//" which doesn't mean
           anything at all.  To include a "-" character in a transliteration,
           put it either first or last.  (In the past, "tr/a-z-0//" was
           synonymous with "tr/a-y//", which was probably not what you would
           have expected.)

       Ambiguous use of %s resolved as %s
           (S ambiguous) You said something that may not be interpreted the
           way you thought.  Normally it's pretty easy to disambiguate it by
           supplying a missing quote, operator, parenthesis pair or
           declaration.

       Ambiguous use of -%s resolved as -&%s()
           (S ambiguous) You wrote something like "-foo", which might be the
           string "-foo", or a call to the function "foo", negated.  If you
           meant the string, just write "-foo".  If you meant the function
           call, write "-foo()".

       Ambiguous use of %c resolved as operator %c
           (S ambiguous) "%", "&", and "*" are both infix operators (modulus,
           bitwise and, and multiplication) and initial special characters
           (denoting hashes, subroutines and typeglobs), and you said
           something like "*foo * foo" that might be interpreted as either of
           them.  We assumed you meant the infix operator, but please try to
           make it more clear -- in the example given, you might write "*foo *
           foo()" if you really meant to multiply a glob by the result of
           calling a function.

       Ambiguous use of %c{%s} resolved to %c%s
           (W ambiguous) You wrote something like "@{foo}", which might be
           asking for the variable @foo, or it might be calling a function
           named foo, and dereferencing it as an array reference.  If you
           wanted the variable, you can just write @foo.  If you wanted to
           call the function, write "@{foo()}" ... or you could just not have
           a variable and a function with the same name, and save yourself a
           lot of trouble.

       Ambiguous use of %c{%s[...]} resolved to %c%s[...]
       Ambiguous use of %c{%s{...}} resolved to %c%s{...}
           (W ambiguous) You wrote something like "${foo[2]}" (where foo
           represents the name of a Perl keyword), which might be looking for
           element number 2 of the array named @foo, in which case please
           write $foo[2], or you might have meant to pass an anonymous
           arrayref to the function named foo, and then do a scalar deref on
           the value it returns.  If you meant that, write "${foo([2])}".

           In regular expressions, the "${foo[2]}" syntax is sometimes
           necessary to disambiguate between array subscripts and character
           classes.  "/$length[2345]/", for instance, will be interpreted as
           $length followed by the character class "[2345]".  If an array
           subscript is what you want, you can avoid the warning by changing
           "/${length[2345]}/" to the unsightly "/${\$length[2345]}/", by
           renaming your array to something that does not coincide with a
           built-in keyword, or by simply turning off warnings with "no
           warnings 'ambiguous';".

       '|' and '<' may not both be specified on command line
           (F) An error peculiar to VMS.  Perl does its own command line
           redirection, and found that STDIN was a pipe, and that you also
           tried to redirect STDIN using '<'.  Only one STDIN stream to a
           customer, please.

       '|' and '>' may not both be specified on command line
           (F) An error peculiar to VMS.  Perl does its own command line
           redirection, and thinks you tried to redirect stdout both to a file
           and into a pipe to another command.  You need to choose one or the
           other, though nothing's stopping you from piping into a program or
           Perl script which 'splits' output into two streams, such as

               open(OUT,">$ARGV[0]") or die "Can't write to $ARGV[0]: $!";
               while (<STDIN>) {
                   print;
                   print OUT;
               }
               close OUT;

       Applying %s to %s will act on scalar(%s)
           (W misc) The pattern match ("//"), substitution ("s///"), and
           transliteration ("tr///") operators work on scalar values.  If you
           apply one of them to an array or a hash, it will convert the array
           or hash to a scalar value (the length of an array, or the
           population info of a hash) and then work on that scalar value.
           This is probably not what you meant to do.  See "grep" in perlfunc
           and "map" in perlfunc for alternatives.

       Arg too short for msgsnd
           (F) msgsnd() requires a string at least as long as sizeof(long).

       Argument "%s" isn't numeric%s
           (W numeric) The indicated string was fed as an argument to an
           operator that expected a numeric value instead.  If you're
           fortunate the message will identify which operator was so
           unfortunate.

           Note that for the "Inf" and "NaN" (infinity and not-a-number) the
           definition of "numeric" is somewhat unusual: the strings themselves
           (like "Inf") are considered numeric, and anything following them is
           considered non-numeric.

       Argument list not closed for PerlIO layer "%s"
           (W layer) When pushing a layer with arguments onto the Perl I/O
           system you forgot the ) that closes the argument list.  (Layers
           take care of transforming data between external and internal
           representations.)  Perl stopped parsing the layer list at this
           point and did not attempt to push this layer.  If your program
           didn't explicitly request the failing operation, it may be the
           result of the value of the environment variable PERLIO.

       Argument "%s" treated as 0 in increment (++)
           (W numeric) The indicated string was fed as an argument to the "++"
           operator which expects either a number or a string matching
           "/^[a-zA-Z]*[0-9]*\z/".  See "Auto-increment and Auto-decrement" in
           perlop for details.

       Array passed to stat will be coerced to a scalar%s
           (W syntax) You called stat() on an array, but the array will be
           coerced to a scalar - the number of elements in the array.

       A signature parameter must start with '$', '@' or '%'
           (F) Each subroutine signature parameter declaration must start with
           a valid sigil; for example:

               sub foo ($a, $, $b = 1, @c) {}

       A slurpy parameter may not have a default value
           (F) Only scalar subroutine signature parameters may have a default
           value; for example:

               sub foo ($a = 1)        {} # legal
               sub foo (@a = (1))      {} # invalid
               sub foo (%a = (a => b)) {} # invalid

       assertion botched: %s
           (X) The malloc package that comes with Perl had an internal
           failure.

       Assertion %s failed: file "%s", line %d
           (X) A general assertion failed.  The file in question must be
           examined.

       Assigned value is not a reference
           (F) You tried to assign something that was not a reference to an
           lvalue reference (e.g., "\$x = $y").  If you meant to make $x an
           alias to $y, use "\$x = \$y".

       Assigned value is not %s reference
           (F) You tried to assign a reference to a reference constructor, but
           the two references were not of the same type.  You cannot alias a
           scalar to an array, or an array to a hash; the two types must
           match.

               \$x = \@y;  # error
               \@x = \%y;  # error
                $y = [];
               \$x = $y;   # error; did you mean \$y?

       Assigning non-zero to $[ is no longer possible
           (F) When the "array_base" feature is disabled (e.g., and under "use
           v5.16;", and as of Perl 5.30) the special variable $[, which is
           deprecated, is now a fixed zero value.

       Assignment to both a list and a scalar
           (F) If you assign to a conditional operator, the 2nd and 3rd
           arguments must either both be scalars or both be lists.  Otherwise
           Perl won't know which context to supply to the right side.

       Assuming NOT a POSIX class since %s in regex; marked by <-- HERE in
       m/%s/
           (W regexp) You had something like these:

            [[:alnum]]
            [[:digit:xyz]

           They look like they might have been meant to be the POSIX classes
           "[:alnum:]" or "[:digit:]".  If so, they should be written:

            [[:alnum:]]
            [[:digit:]xyz]

           Since these aren't legal POSIX class specifications, but are legal
           bracketed character classes, Perl treats them as the latter.  In
           the first example, it matches the characters ":", "[", "a", "l",
           "m", "n", and "u".

           If these weren't meant to be POSIX classes, this warning message is
           spurious, and can be suppressed by reordering things, such as

            [[al:num]]

           or

            [[:munla]]

       <> at require-statement should be quotes
           (F) You wrote "require <file>" when you should have written
           "require 'file'".

       Attempt to access disallowed key '%s' in a restricted hash
           (F) The failing code has attempted to get or set a key which is not
           in the current set of allowed keys of a restricted hash.

       Attempt to bless into a freed package
           (F) You wrote "bless $foo" with one argument after somehow causing
           the current package to be freed.  Perl cannot figure out what to
           do, so it throws up its hands in despair.

       Attempt to bless into a reference
           (F) The CLASSNAME argument to the bless() operator is expected to
           be the name of the package to bless the resulting object into.
           You've supplied instead a reference to something: perhaps you wrote

               bless $self, $proto;

           when you intended

               bless $self, ref($proto) || $proto;

           If you actually want to bless into the stringified version of the
           reference supplied, you need to stringify it yourself, for example
           by:

               bless $self, "$proto";

       Attempt to clear deleted array
           (S debugging) An array was assigned to when it was being freed.
           Freed values are not supposed to be visible to Perl code.  This can
           also happen if XS code calls "av_clear" from a custom magic
           callback on the array.

       Attempt to delete disallowed key '%s' from a restricted hash
           (F) The failing code attempted to delete from a restricted hash a
           key which is not in its key set.

       Attempt to delete readonly key '%s' from a restricted hash
           (F) The failing code attempted to delete a key whose value has been
           declared readonly from a restricted hash.

       Attempt to free non-arena SV: 0x%x
           (S internal) All SV objects are supposed to be allocated from
           arenas that will be garbage collected on exit.  An SV was
           discovered to be outside any of those arenas.

       Attempt to free nonexistent shared string '%s'%s
           (S internal) Perl maintains a reference-counted internal table of
           strings to optimize the storage and access of hash keys and other
           strings.  This indicates someone tried to decrement the reference
           count of a string that can no longer be found in the table.

       Attempt to free temp prematurely: SV 0x%x
           (S debugging) Mortalized values are supposed to be freed by the
           free_tmps() routine.  This indicates that something else is freeing
           the SV before the free_tmps() routine gets a chance, which means
           that the free_tmps() routine will be freeing an unreferenced scalar
           when it does try to free it.

       Attempt to free unreferenced glob pointers
           (S internal) The reference counts got screwed up on symbol aliases.

       Attempt to free unreferenced scalar: SV 0x%x
           (S internal) Perl went to decrement the reference count of a scalar
           to see if it would go to 0, and discovered that it had already gone
           to 0 earlier, and should have been freed, and in fact, probably was
           freed.  This could indicate that SvREFCNT_dec() was called too many
           times, or that SvREFCNT_inc() was called too few times, or that the
           SV was mortalized when it shouldn't have been, or that memory has
           been corrupted.

       Attempt to pack pointer to temporary value
           (W pack) You tried to pass a temporary value (like the result of a
           function, or a computed expression) to the "p" pack() template.
           This means the result contains a pointer to a location that could
           become invalid anytime, even before the end of the current
           statement.  Use literals or global values as arguments to the "p"
           pack() template to avoid this warning.

       Attempt to reload %s aborted.
           (F) You tried to load a file with "use" or "require" that failed to
           compile once already.  Perl will not try to compile this file again
           unless you delete its entry from %INC.  See "require" in perlfunc
           and "%INC" in perlvar.

       Attempt to set length of freed array
           (W misc) You tried to set the length of an array which has been
           freed.  You can do this by storing a reference to the scalar
           representing the last index of an array and later assigning through
           that reference.  For example

               $r = do {my @a; \$#a};
               $$r = 503

       Attempt to use reference as lvalue in substr
           (W substr) You supplied a reference as the first argument to
           substr() used as an lvalue, which is pretty strange.  Perhaps you
           forgot to dereference it first.  See "substr" in perlfunc.

       Attribute prototype(%s) discards earlier prototype attribute in same
       sub
           (W misc) A sub was declared as sub foo : prototype(A) :
           prototype(B) {}, for example.  Since each sub can only have one
           prototype, the earlier declaration(s) are discarded while the last
           one is applied.

       av_reify called on tied array
           (S debugging) This indicates that something went wrong and Perl got
           very confused about @_ or @DB::args being tied.

       Bad arg length for %s, is %u, should be %d
           (F) You passed a buffer of the wrong size to one of msgctl(),
           semctl() or shmctl().  In C parlance, the correct sizes are,
           respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *),
           and sizeof(struct shmid_ds *).

       Bad evalled substitution pattern
           (F) You've used the "/e" switch to evaluate the replacement for a
           substitution, but perl found a syntax error in the code to
           evaluate, most likely an unexpected right brace '}'.

       Bad filehandle: %s
           (F) A symbol was passed to something wanting a filehandle, but the
           symbol has no filehandle associated with it.  Perhaps you didn't do
           an open(), or did it in another package.

       Bad free() ignored
           (S malloc) An internal routine called free() on something that had
           never been malloc()ed in the first place.  Mandatory, but can be
           disabled by setting environment variable "PERL_BADFREE" to 0.

           This message can be seen quite often with DB_File on systems with
           "hard" dynamic linking, like "AIX" and "OS/2".  It is a bug of
           "Berkeley DB" which is left unnoticed if "DB" uses forgiving system
           malloc().

       Bad hash
           (P) One of the internal hash routines was passed a null HV pointer.

       Badly placed ()'s
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       Bad name after %s
           (F) You started to name a symbol by using a package prefix, and
           then didn't finish the symbol.  In particular, you can't
           interpolate outside of quotes, so

               $var = 'myvar';
               $sym = mypack::$var;

           is not the same as

               $var = 'myvar';
               $sym = "mypack::$var";

       Bad plugin affecting keyword '%s'
           (F) An extension using the keyword plugin mechanism violated the
           plugin API.

       Bad realloc() ignored
           (S malloc) An internal routine called realloc() on something that
           had never been malloc()ed in the first place.  Mandatory, but can
           be disabled by setting the environment variable "PERL_BADFREE" to
           1.

       Bad symbol for array
           (P) An internal request asked to add an array entry to something
           that wasn't a symbol table entry.

       Bad symbol for dirhandle
           (P) An internal request asked to add a dirhandle entry to something
           that wasn't a symbol table entry.

       Bad symbol for filehandle
           (P) An internal request asked to add a filehandle entry to
           something that wasn't a symbol table entry.

       Bad symbol for hash
           (P) An internal request asked to add a hash entry to something that
           wasn't a symbol table entry.

       Bad symbol for scalar
           (P) An internal request asked to add a scalar entry to something
           that wasn't a symbol table entry.

       Bareword found in conditional
           (W bareword) The compiler found a bareword where it expected a
           conditional, which often indicates that an || or && was parsed as
           part of the last argument of the previous construct, for example:

               open FOO || die;

           It may also indicate a misspelled constant that has been
           interpreted as a bareword:

               use constant TYPO => 1;
               if (TYOP) { print "foo" }

           The "strict" pragma is useful in avoiding such errors.

       Bareword in require contains "%s"
       Bareword in require maps to disallowed filename "%s"
       Bareword in require maps to empty filename
           (F) The bareword form of require has been invoked with a filename
           which could not have been generated by a valid bareword permitted
           by the parser.  You shouldn't be able to get this error from Perl
           code, but XS code may throw it if it passes an invalid module name
           to "Perl_load_module".

       Bareword in require must not start with a double-colon: "%s"
           (F) In "require Bare::Word", the bareword is not allowed to start
           with a double-colon.  Write "require ::Foo::Bar" as  "require
           Foo::Bar" instead.

       Bareword "%s" not allowed while "strict subs" in use
           (F) With "strict subs" in use, a bareword is only allowed as a
           subroutine identifier, in curly brackets or to the left of the "=>"
           symbol.  Perhaps you need to predeclare a subroutine?

       Bareword "%s" refers to nonexistent package
           (W bareword) You used a qualified bareword of the form "Foo::", but
           the compiler saw no other uses of that namespace before that point.
           Perhaps you need to predeclare a package?

       Bareword filehandle "%s" not allowed under 'no feature
       "bareword_filehandles"'
           (F) You attempted to use a bareword filehandle with the
           "bareword_filehandles" feature disabled.

           Only the built-in handles "STDIN", "STDOUT", "STDERR", "ARGV",
           "ARGVOUT" and "DATA" can be used with the "bareword_filehandles"
           feature disabled.

       BEGIN failed--compilation aborted
           (F) An untrapped exception was raised while executing a BEGIN
           subroutine.  Compilation stops immediately and the interpreter is
           exited.

       BEGIN not safe after errors--compilation aborted
           (F) Perl found a "BEGIN {}" subroutine (or a "use" directive, which
           implies a "BEGIN {}") after one or more compilation errors had
           already occurred.  Since the intended environment for the "BEGIN
           {}" could not be guaranteed (due to the errors), and since
           subsequent code likely depends on its correct operation, Perl just
           gave up.

       \%d better written as $%d
           (W syntax) Outside of patterns, backreferences live on as
           variables.  The use of backslashes is grandfathered on the right-
           hand side of a substitution, but stylistically it's better to use
           the variable form because other Perl programmers will expect it,
           and it works better if there are more than 9 backreferences.

       Binary number > 0b11111111111111111111111111111111 non-portable
           (W portable) The binary number you specified is larger than 2**32-1
           (4294967295) and therefore non-portable between systems.  See
           perlport for more on portability concerns.

       bind() on closed socket %s
           (W closed) You tried to do a bind on a closed socket.  Did you
           forget to check the return value of your socket() call?  See "bind"
           in perlfunc.

       binmode() on closed filehandle %s
           (W unopened) You tried binmode() on a filehandle that was never
           opened.  Check your control flow and number of arguments.

       Bit vector size > 32 non-portable
           (W portable) Using bit vector sizes larger than 32 is non-portable.

       Bizarre copy of %s
           (P) Perl detected an attempt to copy an internal value that is not
           copiable.

       Bizarre SvTYPE [%d]
           (P) When starting a new thread or returning values from a thread,
           Perl encountered an invalid data type.

       Both or neither range ends should be Unicode in regex; marked by
       <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'" or within "(?[...])")

           In a bracketed character class in a regular expression pattern, you
           had a range which has exactly one end of it specified using "\N{}",
           and the other end is specified using a non-portable mechanism.
           Perl treats the range as a Unicode range, that is, all the
           characters in it are considered to be the Unicode characters, and
           which may be different code points on some platforms Perl runs on.
           For example, "[\N{U+06}-\x08]" is treated as if you had instead
           said "[\N{U+06}-\N{U+08}]", that is it matches the characters whose
           code points in Unicode are 6, 7, and 8.  But that "\x08" might
           indicate that you meant something different, so the warning gets
           raised.

       Buffer overflow in prime_env_iter: %s
           (W internal) A warning peculiar to VMS.  While Perl was preparing
           to iterate over %ENV, it encountered a logical name or symbol
           definition which was too long, so it was truncated to the string
           shown.

       Callback called exit
           (F) A subroutine invoked from an external package via call_sv()
           exited by calling exit.

       %s() called too early to check prototype
           (W prototype) You've called a function that has a prototype before
           the parser saw a definition or declaration for it, and Perl could
           not check that the call conforms to the prototype.  You need to
           either add an early prototype declaration for the subroutine in
           question, or move the subroutine definition ahead of the call to
           get proper prototype checking.  Alternatively, if you are certain
           that you're calling the function correctly, you may put an
           ampersand before the name to avoid the warning.  See perlsub.

       Cannot chr %f
           (F) You passed an invalid number (like an infinity or not-a-number)
           to "chr".

       Cannot complete in-place edit of %s: %s
           (F) Your perl script appears to have changed directory while
           performing an in-place edit of a file specified by a relative path,
           and your system doesn't include the directory relative POSIX
           functions needed to handle that.

       Cannot compress %f in pack
           (F) You tried compressing an infinity or not-a-number as an
           unsigned integer with BER, which makes no sense.

       Cannot compress integer in pack
           (F) An argument to pack("w",...) was too large to compress.  The
           BER compressed integer format can only be used with positive
           integers, and you attempted to compress a very large number (>
           1e308).  See "pack" in perlfunc.

       Cannot compress negative numbers in pack
           (F) An argument to pack("w",...) was negative.  The BER compressed
           integer format can only be used with positive integers.  See "pack"
           in perlfunc.

       Cannot convert a reference to %s to typeglob
           (F) You manipulated Perl's symbol table directly, stored a
           reference in it, then tried to access that symbol via conventional
           Perl syntax.  The access triggers Perl to autovivify that typeglob,
           but it there is no legal conversion from that type of reference to
           a typeglob.

       Cannot copy to %s
           (P) Perl detected an attempt to copy a value to an internal type
           that cannot be directly assigned to.

       Cannot find encoding "%s"
           (S io) You tried to apply an encoding that did not exist to a
           filehandle, either with open() or binmode().

       Cannot open %s as a dirhandle: it is already open as a filehandle
           (F) You tried to use opendir() to associate a dirhandle to a symbol
           (glob or scalar) that already holds a filehandle.  Since this idiom
           might render your code confusing, it was deprecated in Perl 5.10.
           As of Perl 5.28, it is a fatal error.

       Cannot open %s as a filehandle: it is already open as a dirhandle
           (F) You tried to use open() to associate a filehandle to a symbol
           (glob or scalar) that already holds a dirhandle.  Since this idiom
           might render your code confusing, it was deprecated in Perl 5.10.
           As of Perl 5.28, it is a fatal error.

       Cannot pack %f with '%c'
           (F) You tried converting an infinity or not-a-number to an integer,
           which makes no sense.

       Cannot printf %f with '%c'
           (F) You tried printing an infinity or not-a-number as a character
           (%c), which makes no sense.  Maybe you meant '%s', or just
           stringifying it?

       Cannot set tied @DB::args
           (F) "caller" tried to set @DB::args, but found it tied.  Tying
           @DB::args is not supported.  (Before this error was added, it used
           to crash.)

       Cannot tie unreifiable array
           (P) You somehow managed to call "tie" on an array that does not
           keep a reference count on its arguments and cannot be made to do
           so.  Such arrays are not even supposed to be accessible to Perl
           code, but are only used internally.

       Cannot yet reorder sv_vcatpvfn() arguments from va_list
           (F) Some XS code tried to use "sv_vcatpvfn()" or a related function
           with a format string that specifies explicit indexes for some of
           the elements, and using a C-style variable-argument list (a
           "va_list").  This is not currently supported.  XS authors wanting
           to do this must instead construct a C array of "SV*" scalars
           containing the arguments.

       Can only compress unsigned integers in pack
           (F) An argument to pack("w",...) was not an integer.  The BER
           compressed integer format can only be used with positive integers,
           and you attempted to compress something else.  See "pack" in
           perlfunc.

       Can't bless non-reference value
           (F) Only hard references may be blessed.  This is how Perl
           "enforces" encapsulation of objects.  See perlobj.

       Can't "break" in a loop topicalizer
           (F) You called "break", but you're in a "foreach" block rather than
           a "given" block.  You probably meant to use "next" or "last".

       Can't "break" outside a given block
           (F) You called "break", but you're not inside a "given" block.

       Can't call method "%s" on an undefined value
           (F) You used the syntax of a method call, but the slot filled by
           the object reference or package name contains an undefined value.
           Something like this will reproduce the error:

               $BADREF = undef;
               process $BADREF 1,2,3;
               $BADREF->process(1,2,3);

       Can't call method "%s" on unblessed reference
           (F) A method call must know in what package it's supposed to run.
           It ordinarily finds this out from the object reference you supply,
           but you didn't supply an object reference in this case.  A
           reference isn't an object reference until it has been blessed.  See
           perlobj.

       Can't call method "%s" without a package or object reference
           (F) You used the syntax of a method call, but the slot filled by
           the object reference or package name contains an expression that
           returns a defined value which is neither an object reference nor a
           package name.  Something like this will reproduce the error:

               $BADREF = 42;
               process $BADREF 1,2,3;
               $BADREF->process(1,2,3);

       Can't call mro_isa_changed_in() on anonymous symbol table
           (P) Perl got confused as to whether a hash was a plain hash or a
           symbol table hash when trying to update @ISA caches.

       Can't call mro_method_changed_in() on anonymous symbol table
           (F) An XS module tried to call "mro_method_changed_in" on a hash
           that was not attached to the symbol table.

       Can't chdir to %s
           (F) You called "perl -x/foo/bar", but /foo/bar is not a directory
           that you can chdir to, possibly because it doesn't exist.

       Can't check filesystem of script "%s" for nosuid
           (P) For some reason you can't check the filesystem of the script
           for nosuid.

       Can't coerce %s to %s in %s
           (F) Certain types of SVs, in particular real symbol table entries
           (typeglobs), can't be forced to stop being what they are.  So you
           can't say things like:

               *foo += 1;

           You CAN say

               $foo = *foo;
               $foo += 1;

           but then $foo no longer contains a glob.

       Can't "continue" outside a when block
           (F) You called "continue", but you're not inside a "when" or
           "default" block.

       Can't create pipe mailbox
           (P) An error peculiar to VMS.  The process is suffering from
           exhausted quotas or other plumbing problems.

       Can't declare %s in "%s"
           (F) Only scalar, array, and hash variables may be declared as "my",
           "our" or "state" variables.  They must have ordinary identifiers as
           names.

       Can't "default" outside a topicalizer
           (F) You have used a "default" block that is neither inside a
           "foreach" loop nor a "given" block.  (Note that this error is
           issued on exit from the "default" block, so you won't get the error
           if you use an explicit "continue".)

       Can't determine class of operator %s, assuming BASEOP
           (S) This warning indicates something wrong in the internals of
           perl.  Perl was trying to find the class (e.g. LISTOP) of a
           particular OP, and was unable to do so. This is likely to be due to
           a bug in the perl internals, or due to a bug in XS code which
           manipulates perl optrees.

       Can't do inplace edit: %s is not a regular file
           (S inplace) You tried to use the -i switch on a special file, such
           as a file in /dev, a FIFO or an uneditable directory.  The file was
           ignored.

       Can't do inplace edit on %s: %s
           (S inplace) The creation of the new file failed for the indicated
           reason.

       Can't do inplace edit: %s would not be unique
           (S inplace) Your filesystem does not support filenames longer than
           14 characters and Perl was unable to create a unique filename
           during inplace editing with the -i switch.  The file was ignored.

       Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".
           (W locale) You are 1) running under ""use locale""; 2) the current
           locale is not a UTF-8 one; 3) you tried to do the designated case-
           change operation on the specified Unicode character; and 4) the
           result of this operation would mix Unicode and locale rules, which
           likely conflict.  Mixing of different rule types is forbidden, so
           the operation was not done; instead the result is the indicated
           value, which is the best available that uses entirely Unicode
           rules.  That turns out to almost always be the original character,
           unchanged.

           It is generally a bad idea to mix non-UTF-8 locales and Unicode,
           and this issue is one of the reasons why.  This warning is raised
           when Unicode rules would normally cause the result of this
           operation to contain a character that is in the range specified by
           the locale, 0..255, and hence is subject to the locale's rules, not
           Unicode's.

           If you are using locale purely for its characteristics related to
           things like its numeric and time formatting (and not "LC_CTYPE"),
           consider using a restricted form of the locale pragma (see "The
           "use locale" pragma" in perllocale) like
           ""use locale ':not_characters'"".

           Note that failed case-changing operations done as a result of case-
           insensitive "/i" regular expression matching will show up in this
           warning as having the "fc" operation (as that is what the regular
           expression engine calls behind the scenes.)

       Can't do waitpid with flags
           (F) This machine doesn't have either waitpid() or wait4(), so only
           waitpid() without flags is emulated.

       Can't emulate -%s on #! line
           (F) The #! line specifies a switch that doesn't make sense at this
           point.  For example, it'd be kind of silly to put a -x on the #!
           line.

       Can't %s %s-endian %ss on this platform
           (F) Your platform's byte-order is neither big-endian nor little-
           endian, or it has a very strange pointer size.  Packing and
           unpacking big- or little-endian floating point values and pointers
           may not be possible.  See "pack" in perlfunc.

       Can't exec "%s": %s
           (W exec) A system(), exec(), or piped open call could not execute
           the named program for the indicated reason.  Typical reasons
           include: the permissions were wrong on the file, the file wasn't
           found in $ENV{PATH}, the executable in question was compiled for
           another architecture, or the #! line in a script points to an
           interpreter that can't be run for similar reasons.  (Or maybe your
           system doesn't support #! at all.)

       Can't exec %s
           (F) Perl was trying to execute the indicated program for you
           because that's what the #! line said.  If that's not what you
           wanted, you may need to mention "perl" on the #! line somewhere.

       Can't execute %s
           (F) You used the -S switch, but the copies of the script to execute
           found in the PATH did not have correct permissions.

       Can't find an opnumber for "%s"
           (F) A string of a form "CORE::word" was given to prototype(), but
           there is no builtin with the name "word".

       Can't find label %s
           (F) You said to goto a label that isn't mentioned anywhere that
           it's possible for us to go to.  See "goto" in perlfunc.

       Can't find %s on PATH
           (F) You used the -S switch, but the script to execute could not be
           found in the PATH.

       Can't find %s on PATH, '.' not in PATH
           (F) You used the -S switch, but the script to execute could not be
           found in the PATH, or at least not with the correct permissions.
           The script exists in the current directory, but PATH prohibits
           running it.

       Can't find string terminator %s anywhere before EOF
           (F) Perl strings can stretch over multiple lines.  This message
           means that the closing delimiter was omitted.  Because bracketed
           quotes count nesting levels, the following is missing its final
           parenthesis:

               print q(The character '(' starts a side comment.);

           If you're getting this error from a here-document, you may have
           included unseen whitespace before or after your closing tag or
           there may not be a linebreak after it.  A good programmer's editor
           will have a way to help you find these characters (or lack of
           characters).  See perlop for the full details on here-documents.

       Can't find Unicode property definition "%s"
       Can't find Unicode property definition "%s" in regex; marked by <--
       HERE in m/%s/
           (F) The named property which you specified via "\p" or "\P" is not
           one known to Perl.  Perhaps you misspelled the name?  See
           "Properties accessible through \p{} and \P{}" in perluniprops for a
           complete list of available official properties.  If it is a user-
           defined property it must have been defined by the time the regular
           expression is matched.

           If you didn't mean to use a Unicode property, escape the "\p",
           either by "\\p" (just the "\p") or by "\Q\p" (the rest of the
           string, or until "\E").

       Can't fork: %s
           (F) A fatal error occurred while trying to fork while opening a
           pipeline.

       Can't fork, trying again in 5 seconds
           (W pipe) A fork in a piped open failed with EAGAIN and will be
           retried after five seconds.

       Can't get filespec - stale stat buffer?
           (S) A warning peculiar to VMS.  This arises because of the
           difference between access checks under VMS and under the Unix model
           Perl assumes.  Under VMS, access checks are done by filename,
           rather than by bits in the stat buffer, so that ACLs and other
           protections can be taken into account.  Unfortunately, Perl assumes
           that the stat buffer contains all the necessary information, and
           passes it, instead of the filespec, to the access-checking routine.
           It will try to retrieve the filespec using the device name and FID
           present in the stat buffer, but this works only if you haven't made
           a subsequent call to the CRTL stat() routine, because the device
           name is overwritten with each call.  If this warning appears, the
           name lookup failed, and the access-checking routine gave up and
           returned FALSE, just to be conservative.  (Note: The access-
           checking routine knows about the Perl "stat" operator and file
           tests, so you shouldn't ever see this warning in response to a Perl
           command; it arises only if some internal code takes stat buffers
           lightly.)

       Can't get pipe mailbox device name
           (P) An error peculiar to VMS.  After creating a mailbox to act as a
           pipe, Perl can't retrieve its name for later use.

       Can't get SYSGEN parameter value for MAXBUF
           (P) An error peculiar to VMS.  Perl asked $GETSYI how big you want
           your mailbox buffers to be, and didn't get an answer.

       Can't "goto" into a binary or list expression
           (F) A "goto" statement was executed to jump into the middle of a
           binary or list expression.  You can't get there from here.  The
           reason for this restriction is that the interpreter would get
           confused as to how many arguments there are, resulting in stack
           corruption or crashes.  This error occurs in cases such as these:

               goto F;
               print do { F: }; # Can't jump into the arguments to print

               goto G;
               $x + do { G: $y }; # How is + supposed to get its first operand?

       Can't "goto" into a "given" block
           (F) A "goto" statement was executed to jump into the middle of a
           "given" block.  You can't get there from here.  See "goto" in
           perlfunc.

       Can't "goto" into the middle of a foreach loop
           (F) A "goto" statement was executed to jump into the middle of a
           foreach loop.  You can't get there from here.  See "goto" in
           perlfunc.

       Can't "goto" out of a pseudo block
           (F) A "goto" statement was executed to jump out of what might look
           like a block, except that it isn't a proper block.  This usually
           occurs if you tried to jump out of a sort() block or subroutine,
           which is a no-no.  See "goto" in perlfunc.

       Can't goto subroutine from an eval-%s
           (F) The "goto subroutine" call can't be used to jump out of an eval
           "string" or block.

       Can't goto subroutine from a sort sub (or similar callback)
           (F) The "goto subroutine" call can't be used to jump out of the
           comparison sub for a sort(), or from a similar callback (such as
           the reduce() function in List::Util).

       Can't goto subroutine outside a subroutine
           (F) The deeply magical "goto subroutine" call can only replace one
           subroutine call for another.  It can't manufacture one out of whole
           cloth.  In general you should be calling it out of only an AUTOLOAD
           routine anyway.  See "goto" in perlfunc.

       Can't ignore signal CHLD, forcing to default
           (W signal) Perl has detected that it is being run with the SIGCHLD
           signal (sometimes known as SIGCLD) disabled.  Since disabling this
           signal will interfere with proper determination of exit status of
           child processes, Perl has reset the signal to its default value.
           This situation typically indicates that the parent program under
           which Perl may be running (e.g. cron) is being very careless.

       Can't kill a non-numeric process ID
           (F) Process identifiers must be (signed) integers.  It is a fatal
           error to attempt to kill() an undefined, empty-string or otherwise
           non-numeric process identifier.

       Can't "last" outside a loop block
           (F) A "last" statement was executed to break out of the current
           block, except that there's this itty bitty problem called there
           isn't a current block.  Note that an "if" or "else" block doesn't
           count as a "loopish" block, as doesn't a block given to sort(),
           map() or grep().  You can usually double the curlies to get the
           same effect though, because the inner curlies will be considered a
           block that loops once.  See "last" in perlfunc.

       Can't linearize anonymous symbol table
           (F) Perl tried to calculate the method resolution order (MRO) of a
           package, but failed because the package stash has no name.

       Can't load '%s' for module %s
           (F) The module you tried to load failed to load a dynamic
           extension.  This may either mean that you upgraded your version of
           perl to one that is incompatible with your old dynamic extensions
           (which is known to happen between major versions of perl), or (more
           likely) that your dynamic extension was built against an older
           version of the library that is installed on your system.  You may
           need to rebuild your old dynamic extensions.

       Can't localize lexical variable %s
           (F) You used local on a variable name that was previously declared
           as a lexical variable using "my" or "state".  This is not allowed.
           If you want to localize a package variable of the same name,
           qualify it with the package name.

       Can't localize through a reference
           (F) You said something like "local $$ref", which Perl can't
           currently handle, because when it goes to restore the old value of
           whatever $ref pointed to after the scope of the local() is
           finished, it can't be sure that $ref will still be a reference.

       Can't locate %s
           (F) You said to "do" (or "require", or "use") a file that couldn't
           be found.  Perl looks for the file in all the locations mentioned
           in @INC, unless the file name included the full path to the file.
           Perhaps you need to set the PERL5LIB or PERL5OPT environment
           variable to say where the extra library is, or maybe the script
           needs to add the library name to @INC.  Or maybe you just
           misspelled the name of the file.  See "require" in perlfunc and
           lib.

       Can't locate auto/%s.al in @INC
           (F) A function (or method) was called in a package which allows
           autoload, but there is no function to autoload.  Most probable
           causes are a misprint in a function/method name or a failure to
           "AutoSplit" the file, say, by doing "make install".

       Can't locate loadable object for module %s in @INC
           (F) The module you loaded is trying to load an external library,
           like for example, foo.so or bar.dll, but the DynaLoader module was
           unable to locate this library.  See DynaLoader.

       Can't locate object method "%s" via package "%s"
           (F) You called a method correctly, and it correctly indicated a
           package functioning as a class, but that package doesn't define
           that particular method, nor does any of its base classes.  See
           perlobj.

       Can't locate object method "%s" via package "%s" (perhaps you forgot to
       load "%s"?)
           (F) You called a method on a class that did not exist, and the
           method could not be found in UNIVERSAL.  This often means that a
           method requires a package that has not been loaded.

       Can't locate package %s for @%s::ISA
           (W syntax) The @ISA array contained the name of another package
           that doesn't seem to exist.

       Can't locate PerlIO%s
           (F) You tried to use in open() a PerlIO layer that does not exist,
           e.g. open(FH, ">:nosuchlayer", "somefile").

       Can't make list assignment to %ENV on this system
           (F) List assignment to %ENV is not supported on some systems,
           notably VMS.

       Can't make loaded symbols global on this platform while loading %s
           (S) A module passed the flag 0x01 to DynaLoader::dl_load_file() to
           request that symbols from the stated file are made available
           globally within the process, but that functionality is not
           available on this platform.  Whilst the module likely will still
           work, this may prevent the perl interpreter from loading other XS-
           based extensions which need to link directly to functions defined
           in the C or XS code in the stated file.

       Can't modify %s in %s
           (F) You aren't allowed to assign to the item indicated, or
           otherwise try to change it, such as with an auto-increment.

       Can't modify nonexistent substring
           (P) The internal routine that does assignment to a substr() was
           handed a NULL.

       Can't modify non-lvalue subroutine call of &%s
       Can't modify non-lvalue subroutine call of &%s in %s
           (F) Subroutines meant to be used in lvalue context should be
           declared as such.  See "Lvalue subroutines" in perlsub.

       Can't modify reference to %s in %s assignment
           (F) Only a limited number of constructs can be used as the argument
           to a reference constructor on the left-hand side of an assignment,
           and what you used was not one of them.  See "Assigning to
           References" in perlref.

       Can't modify reference to localized parenthesized array in list
       assignment
           (F) Assigning to "\local(@array)" or "\(local @array)" is not
           supported, as it is not clear exactly what it should do.  If you
           meant to make @array refer to some other array, use "\@array =
           \@other_array".  If you want to make the elements of @array aliases
           of the scalars referenced on the right-hand side, use "\(@array) =
           @scalar_refs".

       Can't modify reference to parenthesized hash in list assignment
           (F) Assigning to "\(%hash)" is not supported.  If you meant to make
           %hash refer to some other hash, use "\%hash = \%other_hash".  If
           you want to make the elements of %hash into aliases of the scalars
           referenced on the right-hand side, use a hash slice: "\@hash{@keys}
           = @those_scalar_refs".

       Can't msgrcv to read-only var
           (F) The target of a msgrcv must be modifiable to be used as a
           receive buffer.

       Can't "next" outside a loop block
           (F) A "next" statement was executed to reiterate the current block,
           but there isn't a current block.  Note that an "if" or "else" block
           doesn't count as a "loopish" block, as doesn't a block given to
           sort(), map() or grep().  You can usually double the curlies to get
           the same effect though, because the inner curlies will be
           considered a block that loops once.  See "next" in perlfunc.

       Can't open %s: %s
           (S inplace) The implicit opening of a file through use of the "<>"
           filehandle, either implicitly under the "-n" or "-p" command-line
           switches, or explicitly, failed for the indicated reason.  Usually
           this is because you don't have read permission for a file which you
           named on the command line.

           (F) You tried to call perl with the -e switch, but /dev/null (or
           your operating system's equivalent) could not be opened.

       Can't open a reference
           (W io) You tried to open a scalar reference for reading or writing,
           using the 3-arg open() syntax:

               open FH, '>', $ref;

           but your version of perl is compiled without perlio, and this form
           of open is not supported.

       Can't open bidirectional pipe
           (W pipe) You tried to say "open(CMD, "|cmd|")", which is not
           supported.  You can try any of several modules in the Perl library
           to do this, such as IPC::Open2.  Alternately, direct the pipe's
           output to a file using ">", and then read it in under a different
           file handle.

       Can't open error file %s as stderr
           (F) An error peculiar to VMS.  Perl does its own command line
           redirection, and couldn't open the file specified after '2>' or
           '2>>' on the command line for writing.

       Can't open input file %s as stdin
           (F) An error peculiar to VMS.  Perl does its own command line
           redirection, and couldn't open the file specified after '<' on the
           command line for reading.

       Can't open output file %s as stdout
           (F) An error peculiar to VMS.  Perl does its own command line
           redirection, and couldn't open the file specified after '>' or '>>'
           on the command line for writing.

       Can't open output pipe (name: %s)
           (P) An error peculiar to VMS.  Perl does its own command line
           redirection, and couldn't open the pipe into which to send data
           destined for stdout.

       Can't open perl script "%s": %s
           (F) The script you specified can't be opened for the indicated
           reason.

           If you're debugging a script that uses #!, and normally relies on
           the shell's $PATH search, the -S option causes perl to do that
           search, so you don't have to type the path or "`which
           $scriptname`".

       Can't read CRTL environ
           (S) A warning peculiar to VMS.  Perl tried to read an element of
           %ENV from the CRTL's internal environment array and discovered the
           array was missing.  You need to figure out where your CRTL
           misplaced its environ or define PERL_ENV_TABLES (see perlvms) so
           that environ is not searched.

       Can't redeclare "%s" in "%s"
           (F) A "my", "our" or "state" declaration was found within another
           declaration, such as "my ($x, my($y), $z)" or "our (my $x)".

       Can't "redo" outside a loop block
           (F) A "redo" statement was executed to restart the current block,
           but there isn't a current block.  Note that an "if" or "else" block
           doesn't count as a "loopish" block, as doesn't a block given to
           sort(), map() or grep().  You can usually double the curlies to get
           the same effect though, because the inner curlies will be
           considered a block that loops once.  See "redo" in perlfunc.

       Can't remove %s: %s, skipping file
           (S inplace) You requested an inplace edit without creating a backup
           file.  Perl was unable to remove the original file to replace it
           with the modified file.  The file was left unmodified.

       Can't rename in-place work file '%s' to '%s': %s
           (F) When closed implicitly, the temporary file for in-place editing
           couldn't be renamed to the original filename.

       Can't rename %s to %s: %s, skipping file
           (F) The rename done by the -i switch failed for some reason,
           probably because you don't have write permission to the directory.

       Can't reopen input pipe (name: %s) in binary mode
           (P) An error peculiar to VMS.  Perl thought stdin was a pipe, and
           tried to reopen it to accept binary data.  Alas, it failed.

       Can't represent character for Ox%X on this platform
           (F) There is a hard limit to how big a character code point can be
           due to the fundamental properties of UTF-8, especially on EBCDIC
           platforms.  The given code point exceeds that.  The only work-
           around is to not use such a large code point.

       Can't reset %ENV on this system
           (F) You called "reset('E')" or similar, which tried to reset all
           variables in the current package beginning with "E".  In the main
           package, that includes %ENV.  Resetting %ENV is not supported on
           some systems, notably VMS.

       Can't resolve method "%s" overloading "%s" in package "%s"
           (F)(P) Error resolving overloading specified by a method name (as
           opposed to a subroutine reference): no such method callable via the
           package.  If the method name is "???", this is an internal error.

       Can't return %s from lvalue subroutine
           (F) Perl detected an attempt to return illegal lvalues (such as
           temporary or readonly values) from a subroutine used as an lvalue.
           This is not allowed.

       Can't return outside a subroutine
           (F) The return statement was executed in mainline code, that is,
           where there was no subroutine call to return out of.  See perlsub.

       Can't return %s to lvalue scalar context
           (F) You tried to return a complete array or hash from an lvalue
           subroutine, but you called the subroutine in a way that made Perl
           think you meant to return only one value.  You probably meant to
           write parentheses around the call to the subroutine, which tell
           Perl that the call should be in list context.

       Can't stat script "%s"
           (P) For some reason you can't fstat() the script even though you
           have it open already.  Bizarre.

       Can't take log of %g
           (F) For ordinary real numbers, you can't take the logarithm of a
           negative number or zero.  There's a Math::Complex package that
           comes standard with Perl, though, if you really want to do that for
           the negative numbers.

       Can't take sqrt of %g
           (F) For ordinary real numbers, you can't take the square root of a
           negative number.  There's a Math::Complex package that comes
           standard with Perl, though, if you really want to do that.

       Can't undef active subroutine
           (F) You can't undefine a routine that's currently running.  You
           can, however, redefine it while it's running, and you can even
           undef the redefined subroutine while the old routine is running.
           Go figure.

       Can't unweaken a nonreference
           (F) You attempted to unweaken something that was not a reference.
           Only references can be unweakened.

       Can't upgrade %s (%d) to %d
           (P) The internal sv_upgrade routine adds "members" to an SV, making
           it into a more specialized kind of SV.  The top several SV types
           are so specialized, however, that they cannot be interconverted.
           This message indicates that such a conversion was attempted.

       Can't use '%c' after -mname
           (F) You tried to call perl with the -m switch, but you put
           something other than "=" after the module name.

       Can't use a hash as a reference
           (F) You tried to use a hash as a reference, as in "%foo->{"bar"}"
           or "%$ref->{"hello"}".  Versions of perl <= 5.22.0 used to allow
           this syntax, but shouldn't have.  This was deprecated in perl
           5.6.1.

       Can't use an array as a reference
           (F) You tried to use an array as a reference, as in "@foo->[23]" or
           "@$ref->[99]".  Versions of perl <= 5.22.0 used to allow this
           syntax, but shouldn't have.  This was deprecated in perl 5.6.1.

       Can't use anonymous symbol table for method lookup
           (F) The internal routine that does method lookup was handed a
           symbol table that doesn't have a name.  Symbol tables can become
           anonymous for example by undefining stashes: "undef
           %Some::Package::".

       Can't use an undefined value as %s reference
           (F) A value used as either a hard reference or a symbolic reference
           must be a defined value.  This helps to delurk some insidious
           errors.

       Can't use bareword ("%s") as %s ref while "strict refs" in use
           (F) Only hard references are allowed by "strict refs".  Symbolic
           references are disallowed.  See perlref.

       Can't use %! because Errno.pm is not available
           (F) The first time the "%!" hash is used, perl automatically loads
           the Errno.pm module.  The Errno module is expected to tie the %!
           hash to provide symbolic names for $! errno values.

       Can't use both '<' and '>' after type '%c' in %s
           (F) A type cannot be forced to have both big-endian and little-
           endian byte-order at the same time, so this combination of
           modifiers is not allowed.  See "pack" in perlfunc.

       Can't use 'defined(@array)' (Maybe you should just omit the defined()?)
           (F) defined() is not useful on arrays because it checks for an
           undefined scalar value.  If you want to see if the array is empty,
           just use "if (@array) { # not empty }" for example.

       Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)
           (F) "defined()" is not usually right on hashes.

           Although "defined %hash" is false on a plain not-yet-used hash, it
           becomes true in several non-obvious circumstances, including
           iterators, weak references, stash names, even remaining true after
           "undef %hash".  These things make "defined %hash" fairly useless in
           practice, so it now generates a fatal error.

           If a check for non-empty is what you wanted then just put it in
           boolean context (see "Scalar values" in perldata):

               if (%hash) {
                  # not empty
               }

           If you had "defined %Foo::Bar::QUUX" to check whether such a
           package variable exists then that's never really been reliable, and
           isn't a good way to enquire about the features of a package, or
           whether it's loaded, etc.

       Can't use %s for loop variable
           (P) The parser got confused when trying to parse a "foreach" loop.

       Can't use global %s in %s
           (F) You tried to declare a magical variable as a lexical variable.
           This is not allowed, because the magic can be tied to only one
           location (namely the global variable) and it would be incredibly
           confusing to have variables in your program that looked like
           magical variables but weren't.

       Can't use '%c' in a group with different byte-order in %s
           (F) You attempted to force a different byte-order on a type that is
           already inside a group with a byte-order modifier.  For example you
           cannot force little-endianness on a type that is inside a big-
           endian group.

       Can't use "my %s" in sort comparison
           (F) The global variables $a and $b are reserved for sort
           comparisons.  You mentioned $a or $b in the same line as the <=> or
           cmp operator, and the variable had earlier been declared as a
           lexical variable.  Either qualify the sort variable with the
           package name, or rename the lexical variable.

       Can't use %s ref as %s ref
           (F) You've mixed up your reference types.  You have to dereference
           a reference of the type needed.  You can use the ref() function to
           test the type of the reference, if need be.

       Can't use string ("%s") as %s ref while "strict refs" in use
       Can't use string ("%s"...) as %s ref while "strict refs" in use
           (F) You've told Perl to dereference a string, something which "use
           strict" blocks to prevent it happening accidentally.  See "Symbolic
           references" in perlref.  This can be triggered by an "@" or "$" in
           a double-quoted string immediately before interpolating a variable,
           for example in "user @$twitter_id", which says to treat the
           contents of $twitter_id as an array reference; use a "\" to have a
           literal "@" symbol followed by the contents of $twitter_id: "user
           \@$twitter_id".

       Can't use subscript on %s
           (F) The compiler tried to interpret a bracketed expression as a
           subscript.  But to the left of the brackets was an expression that
           didn't look like a hash or array reference, or anything else
           subscriptable.

       Can't use \%c to mean $%c in expression
           (W syntax) In an ordinary expression, backslash is a unary operator
           that creates a reference to its argument.  The use of backslash to
           indicate a backreference to a matched substring is valid only as
           part of a regular expression pattern.  Trying to do this in
           ordinary Perl code produces a value that prints out looking like
           SCALAR(0xdecaf).  Use the $1 form instead.

       Can't weaken a nonreference
           (F) You attempted to weaken something that was not a reference.
           Only references can be weakened.

       Can't "when" outside a topicalizer
           (F) You have used a when() block that is neither inside a "foreach"
           loop nor a "given" block.  (Note that this error is issued on exit
           from the "when" block, so you won't get the error if the match
           fails, or if you use an explicit "continue".)

       Can't x= to read-only value
           (F) You tried to repeat a constant value (often the undefined
           value) with an assignment operator, which implies modifying the
           value itself.  Perhaps you need to copy the value to a temporary,
           and repeat that.

       Character following "\c" must be printable ASCII
           (F) In "\cX", X must be a printable (non-control) ASCII character.

           Note that ASCII characters that don't map to control characters are
           discouraged, and will generate the warning (when enabled) ""\c%c"
           is more clearly written simply as "%s"".

       Character following \%c must be '{' or a single-character Unicode
       property name in regex; marked by <-- HERE in m/%s/
           (F) (In the above the %c is replaced by either "p" or "P".)  You
           specified something that isn't a legal Unicode property name.  Most
           Unicode properties are specified by "\p{...}".  But if the name is
           a single character one, the braces may be omitted.

       Character in 'C' format wrapped in pack
           (W pack) You said

               pack("C", $x)

           where $x is either less than 0 or more than 255; the "C" format is
           only for encoding native operating system characters (ASCII,
           EBCDIC, and so on) and not for Unicode characters, so Perl behaved
           as if you meant

               pack("C", $x & 255)

           If you actually want to pack Unicode codepoints, use the "U" format
           instead.

       Character in 'c' format wrapped in pack
           (W pack) You said

               pack("c", $x)

           where $x is either less than -128 or more than 127; the "c" format
           is only for encoding native operating system characters (ASCII,
           EBCDIC, and so on) and not for Unicode characters, so Perl behaved
           as if you meant

               pack("c", $x & 255);

           If you actually want to pack Unicode codepoints, use the "U" format
           instead.

       Character in '%c' format wrapped in unpack
           (W unpack) You tried something like

              unpack("H", "\x{2a1}")

           where the format expects to process a byte (a character with a
           value below 256), but a higher value was provided instead.  Perl
           uses the value modulus 256 instead, as if you had provided:

              unpack("H", "\x{a1}")

       Character in 'W' format wrapped in pack
           (W pack) You said

               pack("U0W", $x)

           where $x is either less than 0 or more than 255.  However,
           "U0"-mode expects all values to fall in the interval [0, 255], so
           Perl behaved as if you meant:

               pack("U0W", $x & 255)

       Character(s) in '%c' format wrapped in pack
           (W pack) You tried something like

              pack("u", "\x{1f3}b")

           where the format expects to process a sequence of bytes (character
           with a value below 256), but some of the characters had a higher
           value.  Perl uses the character values modulus 256 instead, as if
           you had provided:

              pack("u", "\x{f3}b")

       Character(s) in '%c' format wrapped in unpack
           (W unpack) You tried something like

              unpack("s", "\x{1f3}b")

           where the format expects to process a sequence of bytes (character
           with a value below 256), but some of the characters had a higher
           value.  Perl uses the character values modulus 256 instead, as if
           you had provided:

              unpack("s", "\x{f3}b")

       charnames alias definitions may not contain a sequence of multiple
       spaces; marked by <-- HERE in %s
           (F) You defined a character name which had multiple space
           characters in a row.  Change them to single spaces.  Usually these
           names are defined in the ":alias" import argument to "use
           charnames", but they could be defined by a translator installed
           into $^H{charnames}.  See "CUSTOM ALIASES" in charnames.

       chdir() on unopened filehandle %s
           (W unopened) You tried chdir() on a filehandle that was never
           opened.

       "\c%c" is more clearly written simply as "%s"
           (W syntax) The "\cX" construct is intended to be a way to specify
           non-printable characters.  You used it for a printable one, which
           is better written as simply itself, perhaps preceded by a backslash
           for non-word characters.  Doing it the way you did is not portable
           between ASCII and EBCDIC platforms.

       Cloning substitution context is unimplemented
           (F) Creating a new thread inside the "s///" operator is not
           supported.

       closedir() attempted on invalid dirhandle %s
           (W io) The dirhandle you tried to close is either closed or not
           really a dirhandle.  Check your control flow.

       close() on unopened filehandle %s
           (W unopened) You tried to close a filehandle that was never opened.

       Closure prototype called
           (F) If a closure has attributes, the subroutine passed to an
           attribute handler is the prototype that is cloned when a new
           closure is created.  This subroutine cannot be called.

       \C no longer supported in regex; marked by <-- HERE in m/%s/
           (F) The \C character class used to allow a match of single byte
           within a multi-byte utf-8 character, but was removed in v5.24 as it
           broke encapsulation and its implementation was extremely buggy.  If
           you really need to process the individual bytes, you probably want
           to convert your string to one where each underlying byte is stored
           as a character, with utf8::encode().

       Code missing after '/'
           (F) You had a (sub-)template that ends with a '/'.  There must be
           another template code following the slash.  See "pack" in perlfunc.

       Code point 0x%X is not Unicode, and not portable
           (S non_unicode portable) You had a code point that has never been
           in any standard, so it is likely that languages other than Perl
           will NOT understand it.  This code point also will not fit in a
           32-bit word on ASCII platforms and therefore is non-portable
           between systems.

           At one time, it was legal in some standards to have code points up
           to 0x7FFF_FFFF, but not higher, and this code point is higher.

           Acceptance of these code points is a Perl extension, and you should
           expect that nothing other than Perl can handle them; Perl itself on
           EBCDIC platforms before v5.24 does not handle them.

           Perl also makes no guarantees that the representation of these code
           points won't change at some point in the future, say when machines
           become available that have larger than a 64-bit word.  At that
           time, files containing any of these, written by an older Perl might
           require conversion before being readable by a newer Perl.

       Code point 0x%X is not Unicode, may not be portable
           (S non_unicode) You had a code point above the Unicode maximum of
           U+10FFFF.

           Perl allows strings to contain a superset of Unicode code points,
           but these may not be accepted by other languages/systems.  Further,
           even if these languages/systems accept these large code points,
           they may have chosen a different representation for them than the
           UTF-8-like one that Perl has, which would mean files are not
           exchangeable between them and Perl.

           On EBCDIC platforms, code points above 0x3FFF_FFFF have a different
           representation in Perl v5.24 than before, so any file containing
           these that was written before that version will require conversion
           before being readable by a later Perl.

       %s: Command not found
           (A) You've accidentally run your script through csh or another
           shell instead of Perl.  Check the #! line, or manually feed your
           script into Perl yourself.  The #! line at the top of your file
           could look like

             #!/usr/bin/perl

       %s: command not found
           (A) You've accidentally run your script through bash or another
           shell instead of Perl.  Check the #! line, or manually feed your
           script into Perl yourself.  The #! line at the top of your file
           could look like

             #!/usr/bin/perl

       %s: command not found: %s
           (A) You've accidentally run your script through zsh or another
           shell instead of Perl.  Check the #! line, or manually feed your
           script into Perl yourself.  The #! line at the top of your file
           could look like

             #!/usr/bin/perl

       Compilation failed in require
           (F) Perl could not compile a file specified in a "require"
           statement.  Perl uses this generic message when none of the errors
           that it encountered were severe enough to halt compilation
           immediately.

       Complex regular subexpression recursion limit (%d) exceeded
           (W regexp) The regular expression engine uses recursion in complex
           situations where back-tracking is required.  Recursion depth is
           limited to 32766, or perhaps less in architectures where the stack
           cannot grow arbitrarily.  ("Simple" and "medium" situations are
           handled without recursion and are not subject to a limit.)  Try
           shortening the string under examination; looping in Perl code (e.g.
           with "while") rather than in the regular expression engine; or
           rewriting the regular expression so that it is simpler or
           backtracks less.  (See perlfaq2 for information on Mastering
           Regular Expressions.)

       connect() on closed socket %s
           (W closed) You tried to do a connect on a closed socket.  Did you
           forget to check the return value of your socket() call?  See
           "connect" in perlfunc.

       Constant(%s): Call to &{$^H{%s}} did not return a defined value
           (F) The subroutine registered to handle constant overloading (see
           overload) or a custom charnames handler (see "CUSTOM TRANSLATORS"
           in charnames) returned an undefined value.

       Constant(%s): $^H{%s} is not defined
           (F) The parser found inconsistencies while attempting to define an
           overloaded constant.  Perhaps you forgot to load the corresponding
           overload pragma?

       Constant is not %s reference
           (F) A constant value (perhaps declared using the "use constant"
           pragma) is being dereferenced, but it amounts to the wrong type of
           reference.  The message indicates the type of reference that was
           expected.  This usually indicates a syntax error in dereferencing
           the constant value.  See "Constant Functions" in perlsub and
           constant.

       Constants from lexical variables potentially modified elsewhere are no
       longer permitted
           (F) You wrote something like

               my $var;
               $sub = sub () { $var };

           but $var is referenced elsewhere and could be modified after the
           "sub" expression is evaluated.  Either it is explicitly modified
           elsewhere ("$var = 3") or it is passed to a subroutine or to an
           operator like "printf" or "map", which may or may not modify the
           variable.

           Traditionally, Perl has captured the value of the variable at that
           point and turned the subroutine into a constant eligible for
           inlining.  In those cases where the variable can be modified
           elsewhere, this breaks the behavior of closures, in which the
           subroutine captures the variable itself, rather than its value, so
           future changes to the variable are reflected in the subroutine's
           return value.

           This usage was deprecated, and as of Perl 5.32 is no longer
           allowed, making it possible to change the behavior in the future.

           If you intended for the subroutine to be eligible for inlining,
           then make sure the variable is not referenced elsewhere, possibly
           by copying it:

               my $var2 = $var;
               $sub = sub () { $var2 };

           If you do want this subroutine to be a closure that reflects future
           changes to the variable that it closes over, add an explicit
           "return":

               my $var;
               $sub = sub () { return $var };

       Constant subroutine %s redefined
           (W redefine)(S) You redefined a subroutine which had previously
           been eligible for inlining.  See "Constant Functions" in perlsub
           for commentary and workarounds.

       Constant subroutine %s undefined
           (W misc) You undefined a subroutine which had previously been
           eligible for inlining.  See "Constant Functions" in perlsub for
           commentary and workarounds.

       Constant(%s) unknown
           (F) The parser found inconsistencies either while attempting to
           define an overloaded constant, or when trying to find the character
           name specified in the "\N{...}" escape.  Perhaps you forgot to load
           the corresponding overload pragma?

       :const is experimental
           (S experimental::const_attr) The "const" attribute is experimental.
           If you want to use the feature, disable the warning with "no
           warnings 'experimental::const_attr'", but know that in doing so you
           are taking the risk that your code may break in a future Perl
           version.

       :const is not permitted on named subroutines
           (F) The "const" attribute causes an anonymous subroutine to be run
           and its value captured at the time that it is cloned.  Named
           subroutines are not cloned like this, so the attribute does not
           make sense on them.

       Copy method did not return a reference
           (F) The method which overloads "=" is buggy.  See "Copy
           Constructor" in overload.

       &CORE::%s cannot be called directly
           (F) You tried to call a subroutine in the "CORE::" namespace with
           &foo syntax or through a reference.  Some subroutines in this
           package cannot yet be called that way, but must be called as
           barewords.  Something like this will work:

               BEGIN { *shove = \&CORE::push; }
               shove @array, 1,2,3; # pushes on to @array

       CORE::%s is not a keyword
           (F) The CORE:: namespace is reserved for Perl keywords.

       Corrupted regexp opcode %d > %d
           (P) This is either an error in Perl, or, if you're using one, your
           custom regular expression engine.  If not the latter, report the
           problem to <https://github.com/Perl/perl5/issues>.

       corrupted regexp pointers
           (P) The regular expression engine got confused by what the regular
           expression compiler gave it.

       corrupted regexp program
           (P) The regular expression engine got passed a regexp program
           without a valid magic number.

       Corrupt malloc ptr 0x%x at 0x%x
           (P) The malloc package that comes with Perl had an internal
           failure.

       Count after length/code in unpack
           (F) You had an unpack template indicating a counted-length string,
           but you have also specified an explicit size for the string.  See
           "pack" in perlfunc.

       Declaring references is experimental
           (S experimental::declared_refs) This warning is emitted if you use
           a reference constructor on the right-hand side of "my", "state",
           "our", or "local".  Simply suppress the warning if you want to use
           the feature, but know that in doing so you are taking the risk of
           using an experimental feature which may change or be removed in a
           future Perl version:

               no warnings "experimental::declared_refs";
               use feature "declared_refs";
               $fooref = my \$foo;

       Deep recursion on anonymous subroutine
       Deep recursion on subroutine "%s"
           (W recursion) This subroutine has called itself (directly or
           indirectly) 100 times more than it has returned.  This probably
           indicates an infinite recursion, unless you're writing strange
           benchmark programs, in which case it indicates something else.

           This threshold can be changed from 100, by recompiling the perl
           binary, setting the C pre-processor macro "PERL_SUB_DEPTH_WARN" to
           the desired value.

       (?(DEFINE)....) does not allow branches in regex; marked by <-- HERE in
       m/%s/
           (F) You used something like "(?(DEFINE)...|..)" which is illegal.
           The most likely cause of this error is that you left out a
           parenthesis inside of the "...." part.

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       %s defines neither package nor VERSION--version check failed
           (F) You said something like "use Module 42" but in the Module file
           there are neither package declarations nor a $VERSION.

       delete argument is not a HASH or ARRAY element or slice
           (F) The argument to "delete" must be either a hash or array
           element, such as:

               $foo{$bar}
               $ref->{"susie"}[12]

           or a hash or array slice, such as:

               @foo[$bar, $baz, $xyzzy]
               $ref->[12]->@{"susie", "queue"}

           or a hash key/value or array index/value slice, such as:

               %foo[$bar, $baz, $xyzzy]
               $ref->[12]->%{"susie", "queue"}

       Delimiter for here document is too long
           (F) In a here document construct like "<<FOO", the label "FOO" is
           too long for Perl to handle.  You have to be seriously twisted to
           write code that triggers this error.

       Deprecated use of my() in false conditional. This will be a fatal error
       in Perl 5.30
           (D deprecated) You used a declaration similar to "my $x if 0".
           There has been a long-standing bug in Perl that causes a lexical
           variable not to be cleared at scope exit when its declaration
           includes a false conditional.  Some people have exploited this bug
           to achieve a kind of static variable.  Since we intend to fix this
           bug, we don't want people relying on this behavior.  You can
           achieve a similar static effect by declaring the variable in a
           separate block outside the function, eg

               sub f { my $x if 0; return $x++ }

           becomes

               { my $x; sub f { return $x++ } }

           Beginning with perl 5.10.0, you can also use "state" variables to
           have lexicals that are initialized only once (see feature):

               sub f { state $x; return $x++ }

           This use of "my()" in a false conditional has been deprecated since
           Perl 5.10, and it will become a fatal error in Perl 5.30.

       DESTROY created new reference to dead object '%s'
           (F) A DESTROY() method created a new reference to the object which
           is just being DESTROYed.  Perl is confused, and prefers to abort
           rather than to create a dangling reference.

       Did not produce a valid header
           See "500 Server error".

       %s did not return a true value
           (F) A required (or used) file must return a true value to indicate
           that it compiled correctly and ran its initialization code
           correctly.  It's traditional to end such a file with a "1;", though
           any true value would do.  See "require" in perlfunc.

       (Did you mean &%s instead?)
           (W misc) You probably referred to an imported subroutine &FOO as
           $FOO or some such.

       (Did you mean "local" instead of "our"?)
           (W shadow) Remember that "our" does not localize the declared
           global variable.  You have declared it again in the same lexical
           scope, which seems superfluous.

       (Did you mean $ or @ instead of %?)
           (W) You probably said %hash{$key} when you meant $hash{$key} or
           @hash{@keys}.  On the other hand, maybe you just meant %hash and
           got carried away.

       Died
           (F) You passed die() an empty string (the equivalent of "die """)
           or you called it with no args and $@ was empty.

       Document contains no data
           See "500 Server error".

       %s does not define %s::VERSION--version check failed
           (F) You said something like "use Module 42" but the Module did not
           define a $VERSION.

       '/' does not take a repeat count
           (F) You cannot put a repeat count of any kind right after the '/'
           code.  See "pack" in perlfunc.

       do "%s" failed, '.' is no longer in @INC; did you mean do "./%s"?
           (D deprecated) Previously " do "somefile"; " would search the
           current directory for the specified file.  Since perl v5.26.0, .
           has been removed from @INC by default, so this is no longer true.
           To search the current directory (and only the current directory)
           you can write " do "./somefile"; ".

       Don't know how to get file name
           (P) "PerlIO_getname", a perl internal I/O function specific to VMS,
           was somehow called on another platform.  This should not happen.

       Don't know how to handle magic of type \%o
           (P) The internal handling of magical variables has been cursed.

       do_study: out of memory
           (P) This should have been caught by safemalloc() instead.

       (Do you need to predeclare %s?)
           (S syntax) This is an educated guess made in conjunction with the
           message "%s found where operator expected".  It often means a
           subroutine or module name is being referenced that hasn't been
           declared yet.  This may be because of ordering problems in your
           file, or because of a missing "sub", "package", "require", or "use"
           statement.  If you're referencing something that isn't defined yet,
           you don't actually have to define the subroutine or package before
           the current location.  You can use an empty "sub foo;" or "package
           FOO;" to enter a "forward" declaration.

       dump() must be written as CORE::dump() as of Perl 5.30
           (F) You used the obsolete "dump()" built-in function.  That was
           deprecated in Perl 5.8.0.  As of Perl 5.30 it must be written in
           fully qualified format: "CORE::dump()".

           See "dump" in perlfunc.

       dump is not supported
           (F) Your machine doesn't support dump/undump.

       Duplicate free() ignored
           (S malloc) An internal routine called free() on something that had
           already been freed.

       Duplicate modifier '%c' after '%c' in %s
           (W unpack) You have applied the same modifier more than once after
           a type in a pack template.  See "pack" in perlfunc.

       elseif should be elsif
           (S syntax) There is no keyword "elseif" in Perl because Larry
           thinks it's ugly.  Your code will be interpreted as an attempt to
           call a method named "elseif" for the class returned by the
           following block.  This is unlikely to be what you want.

       Empty \%c in regex; marked by <-- HERE in m/%s/
       Empty \%c{}
       Empty \%c{} in regex; marked by <-- HERE in m/%s/
           (F) You used something like "\b{}", "\B{}", "\o{}", "\p", "\P", or
           "\x" without specifying anything for it to operate on.

           Unfortunately, for backwards compatibility reasons, an empty "\x"
           is legal outside "use re 'strict'" and expands to a NUL character.

       Empty (?) without any modifiers in regex; marked by <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'") "(?)" does nothing, so
           perhaps this is a typo.

       ${^ENCODING} is no longer supported
           (F) The special variable "${^ENCODING}", formerly used to implement
           the "encoding" pragma, is no longer supported as of Perl 5.26.0.

           Setting it to anything other than "undef" is a fatal error as of
           Perl 5.28.

       entering effective %s failed
           (F) While under the "use filetest" pragma, switching the real and
           effective uids or gids failed.

       %ENV is aliased to %s
           (F) You're running under taint mode, and the %ENV variable has been
           aliased to another hash, so it doesn't reflect anymore the state of
           the program's environment.  This is potentially insecure.

       Error converting file specification %s
           (F) An error peculiar to VMS.  Because Perl may have to deal with
           file specifications in either VMS or Unix syntax, it converts them
           to a single form when it must operate on them directly.  Either
           you've passed an invalid file specification to Perl, or you've
           found a case the conversion routines don't handle.  Drat.

       Error %s in expansion of %s
           (F) An error was encountered in handling a user-defined property
           ("User-Defined Character Properties" in perlunicode).  These are
           programmer written subroutines, hence subject to errors that may
           prevent them from compiling or running.  The calls to these subs
           are "eval"'d, and if there is a failure, this message is raised,
           using the contents of $@ from the failed "eval".

           Another possibility is that tainted data was encountered somewhere
           in the chain of expanding the property.  If so, the message wording
           will indicate that this is the problem.  See "Insecure user-defined
           property %s".

       Eval-group in insecure regular expression
           (F) Perl detected tainted data when trying to compile a regular
           expression that contains the "(?{ ... })" zero-width assertion,
           which is unsafe.  See "(?{ code })" in perlre, and perlsec.

       Eval-group not allowed at runtime, use re 'eval' in regex m/%s/
           (F) Perl tried to compile a regular expression containing the "(?{
           ... })" zero-width assertion at run time, as it would when the
           pattern contains interpolated values.  Since that is a security
           risk, it is not allowed.  If you insist, you may still do this by
           using the "re 'eval'" pragma or by explicitly building the pattern
           from an interpolated string at run time and using that in an
           eval().  See "(?{ code })" in perlre.

       Eval-group not allowed, use re 'eval' in regex m/%s/
           (F) A regular expression contained the "(?{ ... })" zero-width
           assertion, but that construct is only allowed when the "use re
           'eval'" pragma is in effect.  See "(?{ code })" in perlre.

       EVAL without pos change exceeded limit in regex; marked by <-- HERE in
       m/%s/
           (F) You used a pattern that nested too many EVAL calls without
           consuming any text.  Restructure the pattern so that text is
           consumed.

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       Excessively long <> operator
           (F) The contents of a <> operator may not exceed the maximum size
           of a Perl identifier.  If you're just trying to glob a long list of
           filenames, try using the glob() operator, or put the filenames into
           a variable and glob that.

       exec? I'm not *that* kind of operating system
           (F) The "exec" function is not implemented on some systems, e.g.
           Catamount. See perlport.

       %sExecution of %s aborted due to compilation errors.
           (F) The final summary message when a Perl compilation fails.

       exists argument is not a HASH or ARRAY element or a subroutine
           (F) The argument to "exists" must be a hash or array element or a
           subroutine with an ampersand, such as:

               $foo{$bar}
               $ref->{"susie"}[12]
               &do_something

       exists argument is not a subroutine name
           (F) The argument to "exists" for "exists &sub" must be a subroutine
           name, and not a subroutine call.  "exists &sub()" will generate
           this error.

       Exiting eval via %s
           (W exiting) You are exiting an eval by unconventional means, such
           as a goto, or a loop control statement.

       Exiting format via %s
           (W exiting) You are exiting a format by unconventional means, such
           as a goto, or a loop control statement.

       Exiting pseudo-block via %s
           (W exiting) You are exiting a rather special block construct (like
           a sort block or subroutine) by unconventional means, such as a
           goto, or a loop control statement.  See "sort" in perlfunc.

       Exiting subroutine via %s
           (W exiting) You are exiting a subroutine by unconventional means,
           such as a goto, or a loop control statement.

       Exiting substitution via %s
           (W exiting) You are exiting a substitution by unconventional means,
           such as a return, a goto, or a loop control statement.

       Expecting close bracket in regex; marked by <-- HERE in m/%s/
           (F) You wrote something like

            (?13

           to denote a capturing group of the form "(?PARNO)", but omitted the
           ")".

       Expecting interpolated extended charclass in regex; marked by <-- HERE
       in m/%s/
           (F) It looked like you were attempting to interpolate an already-
           compiled extended character class, like so:

            my $thai_or_lao = qr/(?[ \p{Thai} + \p{Lao} ])/;
            ...
            qr/(?[ \p{Digit} & $thai_or_lao ])/;

           But the marked code isn't syntactically correct to be such an
           interpolated class.

       Experimental aliasing via reference not enabled
           (F) To do aliasing via references, you must first enable the
           feature:

               no warnings "experimental::refaliasing";
               use feature "refaliasing";
               \$x = \$y;

       Experimental %s on scalar is now forbidden
           (F) An experimental feature added in Perl 5.14 allowed "each",
           "keys", "push", "pop", "shift", "splice", "unshift", and "values"
           to be called with a scalar argument.  This experiment is considered
           unsuccessful, and has been removed.  The "postderef" feature may
           meet your needs better.

       Experimental subroutine signatures not enabled
           (F) To use subroutine signatures, you must first enable them:

               no warnings "experimental::signatures";
               use feature "signatures";
               sub foo ($left, $right) { ... }

       Explicit blessing to '' (assuming package main)
           (W misc) You are blessing a reference to a zero length string.
           This has the effect of blessing the reference into the package
           main.  This is usually not what you want.  Consider providing a
           default target package, e.g. bless($ref, $p || 'MyPackage');

       %s: Expression syntax
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       %s failed--call queue aborted
           (F) An untrapped exception was raised while executing a UNITCHECK,
           CHECK, INIT, or END subroutine.  Processing of the remainder of the
           queue of such routines has been prematurely ended.

       Failed to close in-place work file %s: %s
           (F) Closing an output file from in-place editing, as with the "-i"
           command-line switch, failed.

       False [] range "%s" in regex; marked by <-- HERE in m/%s/
           (W regexp)(F) A character class range must start and end at a
           literal character, not another character class like "\d" or
           "[:alpha:]".  The "-" in your false range is interpreted as a
           literal "-".  In a "(?[...])"  construct, this is an error, rather
           than a warning.  Consider quoting the "-", "\-".  The <-- HERE
           shows whereabouts in the regular expression the problem was
           discovered.  See perlre.

       Fatal VMS error (status=%d) at %s, line %d
           (P) An error peculiar to VMS.  Something untoward happened in a VMS
           system service or RTL routine; Perl's exit status should provide
           more details.  The filename in "at %s" and the line number in "line
           %d" tell you which section of the Perl source code is distressed.

       fcntl is not implemented
           (F) Your machine apparently doesn't implement fcntl().  What is
           this, a PDP-11 or something?

       FETCHSIZE returned a negative value
           (F) A tied array claimed to have a negative number of elements,
           which is not possible.

       Field too wide in 'u' format in pack
           (W pack) Each line in an uuencoded string starts with a length
           indicator which can't encode values above 63.  So there is no point
           in asking for a line length bigger than that.  Perl will behave as
           if you specified "u63" as the format.

       File::Glob::glob() will disappear in perl 5.30. Use
       File::Glob::bsd_glob() instead.
           (D deprecated) "File::Glob" has a function called "glob", which
           just calls "bsd_glob". However, its prototype is different from the
           prototype of "CORE::glob", and hence, "File::Glob::glob" should not
           be used.

           "File::Glob::glob()" was deprecated in perl 5.8.0. A deprecation
           message was issued from perl 5.26.0 onwards, and the function will
           disappear in perl 5.30.0.

           Code using "File::Glob::glob()" should call
           "File::Glob::bsd_glob()" instead.

       Filehandle %s opened only for input
           (W io) You tried to write on a read-only filehandle.  If you
           intended it to be a read-write filehandle, you needed to open it
           with "+<" or "+>" or "+>>" instead of with "<" or nothing.  If you
           intended only to write the file, use ">" or ">>".  See "open" in
           perlfunc.

       Filehandle %s opened only for output
           (W io) You tried to read from a filehandle opened only for writing,
           If you intended it to be a read/write filehandle, you needed to
           open it with "+<" or "+>" or "+>>" instead of with ">".  If you
           intended only to read from the file, use "<".  See "open" in
           perlfunc.  Another possibility is that you attempted to open
           filedescriptor 0 (also known as STDIN) for output (maybe you closed
           STDIN earlier?).

       Filehandle %s reopened as %s only for input
           (W io) You opened for reading a filehandle that got the same
           filehandle id as STDOUT or STDERR.  This occurred because you
           closed STDOUT or STDERR previously.

       Filehandle STDIN reopened as %s only for output
           (W io) You opened for writing a filehandle that got the same
           filehandle id as STDIN.  This occurred because you closed STDIN
           previously.

       Final $ should be \$ or $name
           (F) You must now decide whether the final $ in a string was meant
           to be a literal dollar sign, or was meant to introduce a variable
           name that happens to be missing.  So you have to put either the
           backslash or the name.

       flock() on closed filehandle %s
           (W closed) The filehandle you're attempting to flock() got itself
           closed some time before now.  Check your control flow.  flock()
           operates on filehandles.  Are you attempting to call flock() on a
           dirhandle by the same name?

       Format not terminated
           (F) A format must be terminated by a line with a solitary dot.
           Perl got to the end of your file without finding such a line.

       Format %s redefined
           (W redefine) You redefined a format.  To suppress this warning, say

               {
                   no warnings 'redefine';
                   eval "format NAME =...";
               }

       Found = in conditional, should be ==
           (W syntax) You said

               if ($foo = 123)

           when you meant

               if ($foo == 123)

           (or something like that).

       %s found where operator expected
           (S syntax) The Perl lexer knows whether to expect a term or an
           operator.  If it sees what it knows to be a term when it was
           expecting to see an operator, it gives you this warning.  Usually
           it indicates that an operator or delimiter was omitted, such as a
           semicolon.

       gdbm store returned %d, errno %d, key "%s"
           (S) A warning from the GDBM_File extension that a store failed.

       gethostent not implemented
           (F) Your C library apparently doesn't implement gethostent(),
           probably because if it did, it'd feel morally obligated to return
           every hostname on the Internet.

       get%sname() on closed socket %s
           (W closed) You tried to get a socket or peer socket name on a
           closed socket.  Did you forget to check the return value of your
           socket() call?

       getpwnam returned invalid UIC %#o for user "%s"
           (S) A warning peculiar to VMS.  The call to "sys$getuai" underlying
           the "getpwnam" operator returned an invalid UIC.

       getsockopt() on closed socket %s
           (W closed) You tried to get a socket option on a closed socket.
           Did you forget to check the return value of your socket() call?
           See "getsockopt" in perlfunc.

       given is experimental
           (S experimental::smartmatch) "given" depends on smartmatch, which
           is experimental, so its behavior may change or even be removed in
           any future release of perl.  See the explanation under
           "Experimental Details on given and when" in perlsyn.

       Global symbol "%s" requires explicit package name (did you forget to
       declare "my %s"?)
           (F) You've said "use strict" or "use strict vars", which indicates
           that all variables must either be lexically scoped (using "my" or
           "state"), declared beforehand using "our", or explicitly qualified
           to say which package the global variable is in (using "::").

       glob failed (%s)
           (S glob) Something went wrong with the external program(s) used for
           "glob" and "<*.c>".  Usually, this means that you supplied a "glob"
           pattern that caused the external program to fail and exit with a
           nonzero status.  If the message indicates that the abnormal exit
           resulted in a coredump, this may also mean that your csh (C shell)
           is broken.  If so, you should change all of the csh-related
           variables in config.sh:  If you have tcsh, make the variables refer
           to it as if it were csh (e.g. "full_csh='/usr/bin/tcsh'");
           otherwise, make them all empty (except that "d_csh" should be
           'undef') so that Perl will think csh is missing.  In either case,
           after editing config.sh, run "./Configure -S" and rebuild Perl.

       Glob not terminated
           (F) The lexer saw a left angle bracket in a place where it was
           expecting a term, so it's looking for the corresponding right angle
           bracket, and not finding it.  Chances are you left some needed
           parentheses out earlier in the line, and you really meant a "less
           than".

       gmtime(%f) failed
           (W overflow) You called "gmtime" with a number that it could not
           handle: too large, too small, or NaN.  The returned value is
           "undef".

       gmtime(%f) too large
           (W overflow) You called "gmtime" with a number that was larger than
           it can reliably handle and "gmtime" probably returned the wrong
           date.  This warning is also triggered with NaN (the special not-a-
           number value).

       gmtime(%f) too small
           (W overflow) You called "gmtime" with a number that was smaller
           than it can reliably handle and "gmtime" probably returned the
           wrong date.

       Got an error from DosAllocMem
           (P) An error peculiar to OS/2.  Most probably you're using an
           obsolete version of Perl, and this should not happen anyway.

       goto must have label
           (F) Unlike with "next" or "last", you're not allowed to goto an
           unspecified destination.  See "goto" in perlfunc.

       Goto undefined subroutine%s
           (F) You tried to call a subroutine with "goto &sub" syntax, but the
           indicated subroutine hasn't been defined, or if it was, it has
           since been undefined.

       Group name must start with a non-digit word character in regex; marked
       by <-- HERE in m/%s/
           (F) Group names must follow the rules for perl identifiers, meaning
           they must start with a non-digit word character.  A common cause of
           this error is using (?&0) instead of (?0).  See perlre.

       ()-group starts with a count
           (F) A ()-group started with a count.  A count is supposed to follow
           something: a template character or a ()-group.  See "pack" in
           perlfunc.

       %s had compilation errors.
           (F) The final summary message when a "perl -c" fails.

       Had to create %s unexpectedly
           (S internal) A routine asked for a symbol from a symbol table that
           ought to have existed already, but for some reason it didn't, and
           had to be created on an emergency basis to prevent a core dump.

       %s has too many errors
           (F) The parser has given up trying to parse the program after 10
           errors.  Further error messages would likely be uninformative.

       Hexadecimal float: exponent overflow
           (W overflow) The hexadecimal floating point has a larger exponent
           than the floating point supports.

       Hexadecimal float: exponent underflow
           (W overflow) The hexadecimal floating point has a smaller exponent
           than the floating point supports.  With the IEEE 754 floating
           point, this may also mean that the subnormals (formerly known as
           denormals) are being used, which may or may not be an error.

       Hexadecimal float: internal error (%s)
           (F) Something went horribly bad in hexadecimal float handling.

       Hexadecimal float: mantissa overflow
           (W overflow) The hexadecimal floating point literal had more bits
           in the mantissa (the part between the 0x and the exponent, also
           known as the fraction or the significand) than the floating point
           supports.

       Hexadecimal float: precision loss
           (W overflow) The hexadecimal floating point had internally more
           digits than could be output.  This can be caused by unsupported
           long double formats, or by 64-bit integers not being available
           (needed to retrieve the digits under some configurations).

       Hexadecimal float: unsupported long double format
           (F) You have configured Perl to use long doubles but the internals
           of the long double format are unknown; therefore the hexadecimal
           float output is impossible.

       Hexadecimal number > 0xffffffff non-portable
           (W portable) The hexadecimal number you specified is larger than
           2**32-1 (4294967295) and therefore non-portable between systems.
           See perlport for more on portability concerns.

       Identifier too long
           (F) Perl limits identifiers (names for variables, functions, etc.)
           to about 250 characters for simple names, and somewhat more for
           compound names (like $A::B).  You've exceeded Perl's limits.
           Future versions of Perl are likely to eliminate these arbitrary
           limitations.

       Ignoring zero length \N{} in character class in regex; marked by
       <-- HERE in m/%s/
           (W regexp) Named Unicode character escapes ("\N{...}") may return a
           zero-length sequence.  When such an escape is used in a character
           class its behavior is not well defined.  Check that the correct
           escape has been used, and the correct charname handler is in scope.

       Illegal %s digit '%c' ignored
           (W digit) Here %s is one of "binary", "octal", or "hex".  You may
           have tried to use a digit other than one that is legal for the
           given type, such as only 0 and 1 for binary.  For octals, this is
           raised only if the illegal character is an '8' or '9'.  For hex,
           'A' - 'F' and 'a' - 'f' are legal.  Interpretation of the number
           stopped just before the offending digit or character.

       Illegal binary digit '%c'
           (F) You used a digit other than 0 or 1 in a binary number.

       Illegal character after '_' in prototype for %s : %s
           (W illegalproto) An illegal character was found in a prototype
           declaration.  The '_' in a prototype must be followed by a ';',
           indicating the rest of the parameters are optional, or one of '@'
           or '%', since those two will accept 0 or more final parameters.

       Illegal character \%o (carriage return)
           (F) Perl normally treats carriage returns in the program text as it
           would any other whitespace, which means you should never see this
           error when Perl was built using standard options.  For some reason,
           your version of Perl appears to have been built without this
           support.  Talk to your Perl administrator.

       Illegal character following sigil in a subroutine signature
           (F) A parameter in a subroutine signature contained an unexpected
           character following the "$", "@" or "%" sigil character.  Normally
           the sigil should be followed by the variable name or "=" etc.
           Perhaps you are trying use a prototype while in the scope of "use
           feature 'signatures'"?  For example:

               sub foo ($$) {}            # legal - a prototype

               use feature 'signatures;
               sub foo ($$) {}            # illegal - was expecting a signature
               sub foo ($a, $b)
                       :prototype($$) {}  # legal

       Illegal character in prototype for %s : %s
           (W illegalproto) An illegal character was found in a prototype
           declaration.  Legal characters in prototypes are $, @, %, *, ;, [,
           ], &, \, and +.  Perhaps you were trying to write a subroutine
           signature but didn't enable that feature first ("use feature
           'signatures'"), so your signature was instead interpreted as a bad
           prototype.

       Illegal declaration of anonymous subroutine
           (F) When using the "sub" keyword to construct an anonymous
           subroutine, you must always specify a block of code.  See perlsub.

       Illegal declaration of subroutine %s
           (F) A subroutine was not declared correctly.  See perlsub.

       Illegal division by zero
           (F) You tried to divide a number by 0.  Either something was wrong
           in your logic, or you need to put a conditional in to guard against
           meaningless input.

       Illegal modulus zero
           (F) You tried to divide a number by 0 to get the remainder.  Most
           numbers don't take to this kindly.

       Illegal number of bits in vec
           (F) The number of bits in vec() (the third argument) must be a
           power of two from 1 to 32 (or 64, if your platform supports that).

       Illegal octal digit '%c'
           (F) You used an 8 or 9 in an octal number.

       Illegal operator following parameter in a subroutine signature
           (F) A parameter in a subroutine signature, was followed by
           something other than "=" introducing a default, "," or ")".

               use feature 'signatures';
               sub foo ($=1) {}           # legal
               sub foo ($a = 1) {}        # legal
               sub foo ($a += 1) {}       # illegal
               sub foo ($a == 1) {}       # illegal

       Illegal pattern in regex; marked by <-- HERE in m/%s/
           (F) You wrote something like

            (?+foo)

           The "+" is valid only when followed by digits, indicating a
           capturing group.  See "(?PARNO)".

       Illegal suidscript
           (F) The script run under suidperl was somehow illegal.

       Illegal switch in PERL5OPT: -%c
           (X) The PERL5OPT environment variable may only be used to set the
           following switches: -[CDIMUdmtw].

       Illegal user-defined property name
           (F) You specified a Unicode-like property name in a regular
           expression pattern (using "\p{}" or "\P{}") that Perl knows isn't
           an official Unicode property, and was likely meant to be a user-
           defined property name, but it can't be one of those, as they must
           begin with either "In" or "Is".  Check the spelling.  See also
           "Can't find Unicode property definition "%s"".

       Ill-formed CRTL environ value "%s"
           (W internal) A warning peculiar to VMS.  Perl tried to read the
           CRTL's internal environ array, and encountered an element without
           the "=" delimiter used to separate keys from values.  The element
           is ignored.

       Ill-formed message in prime_env_iter: |%s|
           (W internal) A warning peculiar to VMS.  Perl tried to read a
           logical name or CLI symbol definition when preparing to iterate
           over %ENV, and didn't see the expected delimiter between key and
           value, so the line was ignored.

       (in cleanup) %s
           (W misc) This prefix usually indicates that a DESTROY() method
           raised the indicated exception.  Since destructors are usually
           called by the system at arbitrary points during execution, and
           often a vast number of times, the warning is issued only once for
           any number of failures that would otherwise result in the same
           message being repeated.

           Failure of user callbacks dispatched using the "G_KEEPERR" flag
           could also result in this warning.  See "G_KEEPERR" in perlcall.

       Incomplete expression within '(?[ ])' in regex; marked by <-- HERE in
       m/%s/
           (F) There was a syntax error within the "(?[ ])".  This can happen
           if the expression inside the construct was completely empty, or if
           there are too many or few operands for the number of operators.
           Perl is not smart enough to give you a more precise indication as
           to what is wrong.

       Inconsistent hierarchy during C3 merge of class '%s': merging failed on
       parent '%s'
           (F) The method resolution order (MRO) of the given class is not
           C3-consistent, and you have enabled the C3 MRO for this class.  See
           the C3 documentation in mro for more information.

       Indentation on line %d of here-doc doesn't match delimiter
           (F) You have an indented here-document where one or more of its
           lines have whitespace at the beginning that does not match the
           closing delimiter.

           For example, line 2 below is wrong because it does not have at
           least 2 spaces, but lines 1 and 3 are fine because they have at
           least 2:

               if ($something) {
                 print <<~EOF;
                   Line 1
                  Line 2 not
                     Line 3
                   EOF
               }

           Note that tabs and spaces are compared strictly, meaning 1 tab will
           not match 8 spaces.

       Infinite recursion in regex
           (F) You used a pattern that references itself without consuming any
           input text.  You should check the pattern to ensure that recursive
           patterns either consume text or fail.

       Infinite recursion in user-defined property
           (F) A user-defined property ("User-Defined Character Properties" in
           perlunicode) can depend on the definitions of other user-defined
           properties.  If the chain of dependencies leads back to this
           property, infinite recursion would occur, were it not for the check
           that raised this error.

           Restructure your property definitions to avoid this.

       Infinite recursion via empty pattern
           (F) You tried to use the empty pattern inside of a regex code
           block, for instance "/(?{ s!!! })/", which resulted in re-executing
           the same pattern, which is an infinite loop which is broken by
           throwing an exception.

       Initialization of state variables in list currently forbidden
           (F) "state" only permits initializing a single variable, specified
           without parentheses.  So "state $a = 42" and "state @a = qw(a b c)"
           are allowed, but not "state ($a) = 42" or "(state $a) = 42".  To
           initialize more than one "state" variable, initialize them one at a
           time.

       %%s[%s] in scalar context better written as $%s[%s]
           (W syntax) In scalar context, you've used an array index/value
           slice (indicated by %) to select a single element of an array.
           Generally it's better to ask for a scalar value (indicated by $).
           The difference is that $foo[&bar] always behaves like a scalar,
           both in the value it returns and when evaluating its argument,
           while %foo[&bar] provides a list context to its subscript, which
           can do weird things if you're expecting only one subscript.  When
           called in list context, it also returns the index (what &bar
           returns) in addition to the value.

       %%s{%s} in scalar context better written as $%s{%s}
           (W syntax) In scalar context, you've used a hash key/value slice
           (indicated by %) to select a single element of a hash.  Generally
           it's better to ask for a scalar value (indicated by $).  The
           difference is that $foo{&bar} always behaves like a scalar, both in
           the value it returns and when evaluating its argument, while
           @foo{&bar} and provides a list context to its subscript, which can
           do weird things if you're expecting only one subscript.  When
           called in list context, it also returns the key in addition to the
           value.

       Insecure dependency in %s
           (F) You tried to do something that the tainting mechanism didn't
           like.  The tainting mechanism is turned on when you're running
           setuid or setgid, or when you specify -T to turn it on explicitly.
           The tainting mechanism labels all data that's derived directly or
           indirectly from the user, who is considered to be unworthy of your
           trust.  If any such data is used in a "dangerous" operation, you
           get this error.  See perlsec for more information.

       Insecure directory in %s
           (F) You can't use system(), exec(), or a piped open in a setuid or
           setgid script if $ENV{PATH} contains a directory that is writable
           by the world.  Also, the PATH must not contain any relative
           directory.  See perlsec.

       Insecure $ENV{%s} while running %s
           (F) You can't use system(), exec(), or a piped open in a setuid or
           setgid script if any of $ENV{PATH}, $ENV{IFS}, $ENV{CDPATH},
           $ENV{ENV}, $ENV{BASH_ENV} or $ENV{TERM} are derived from data
           supplied (or potentially supplied) by the user.  The script must
           set the path to a known value, using trustworthy data.  See
           perlsec.

       Insecure user-defined property %s
           (F) Perl detected tainted data when trying to compile a regular
           expression that contains a call to a user-defined character
           property function, i.e. "\p{IsFoo}" or "\p{InFoo}".  See "User-
           Defined Character Properties" in perlunicode and perlsec.

       Integer overflow in format string for %s
           (F) The indexes and widths specified in the format string of
           "printf()" or "sprintf()" are too large.  The numbers must not
           overflow the size of integers for your architecture.

       Integer overflow in %s number
           (S overflow) The hexadecimal, octal or binary number you have
           specified either as a literal or as an argument to hex() or oct()
           is too big for your architecture, and has been converted to a
           floating point number.  On a 32-bit architecture the largest
           hexadecimal, octal or binary number representable without overflow
           is 0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111
           respectively.  Note that Perl transparently promotes all numbers to
           a floating point representation internally--subject to loss of
           precision errors in subsequent operations.

       Integer overflow in srand
           (S overflow) The number you have passed to srand is too big to fit
           in your architecture's integer representation.  The number has been
           replaced with the largest integer supported (0xFFFFFFFF on 32-bit
           architectures).  This means you may be getting less randomness than
           you expect, because different random seeds above the maximum will
           return the same sequence of random numbers.

       Integer overflow in version
       Integer overflow in version %d
           (W overflow) Some portion of a version initialization is too large
           for the size of integers for your architecture.  This is not a
           warning because there is no rational reason for a version to try
           and use an element larger than typically 2**32.  This is usually
           caused by trying to use some odd mathematical operation as a
           version, like 100/9.

       Internal disaster in regex; marked by <-- HERE in m/%s/
           (P) Something went badly wrong in the regular expression parser.
           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       Internal inconsistency in tracking vforks
           (S) A warning peculiar to VMS.  Perl keeps track of the number of
           times you've called "fork" and "exec", to determine whether the
           current call to "exec" should affect the current script or a
           subprocess (see "exec LIST" in perlvms).  Somehow, this count has
           become scrambled, so Perl is making a guess and treating this
           "exec" as a request to terminate the Perl script and execute the
           specified command.

       internal %<num>p might conflict with future printf extensions
           (S internal) Perl's internal routine that handles "printf" and
           "sprintf" formatting follows a slightly different set of rules when
           called from C or XS code.  Specifically, formats consisting of
           digits followed by "p" (e.g., "%7p") are reserved for future use.
           If you see this message, then an XS module tried to call that
           routine with one such reserved format.

       Internal urp in regex; marked by <-- HERE in m/%s/
           (P) Something went badly awry in the regular expression parser.
           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       %s (...) interpreted as function
           (W syntax) You've run afoul of the rule that says that any list
           operator followed by parentheses turns into a function, with all
           the list operators arguments found inside the parentheses.  See
           "Terms and List Operators (Leftward)" in perlop.

       In '(?...)', the '(' and '?' must be adjacent in regex; marked by
       <-- HERE in m/%s/
           (F) The two-character sequence "(?" in this context in a regular
           expression pattern should be an indivisible token, with nothing
           intervening between the "(" and the "?", but you separated them
           with whitespace.

       In '(*...)', the '(' and '*' must be adjacent in regex; marked by
       <-- HERE in m/%s/
           (F) The two-character sequence "(*" in this context in a regular
           expression pattern should be an indivisible token, with nothing
           intervening between the "(" and the "*", but you separated them.
           Fix the pattern and retry.

       Invalid %s attribute: %s
           (F) The indicated attribute for a subroutine or variable was not
           recognized by Perl or by a user-supplied handler.  See attributes.

       Invalid %s attributes: %s
           (F) The indicated attributes for a subroutine or variable were not
           recognized by Perl or by a user-supplied handler.  See attributes.

       Invalid character in charnames alias definition; marked by <-- HERE in
       '%s
           (F) You tried to create a custom alias for a character name, with
           the ":alias" option to "use charnames" and the specified character
           in the indicated name isn't valid.  See "CUSTOM ALIASES" in
           charnames.

       Invalid \0 character in %s for %s: %s\0%s
           (W syscalls) Embedded \0 characters in pathnames or other system
           call arguments produce a warning as of 5.20.  The parts after the
           \0 were formerly ignored by system calls.

       Invalid character in \N{...}; marked by <-- HERE in \N{%s}
           (F) Only certain characters are valid for character names.  The
           indicated one isn't.  See "CUSTOM ALIASES" in charnames.

       Invalid conversion in %s: "%s"
           (W printf) Perl does not understand the given format conversion.
           See "sprintf" in perlfunc.

       Invalid escape in the specified encoding in regex; marked by <-- HERE
       in m/%s/
           (W regexp)(F) The numeric escape (for example "\xHH") of value <
           256 didn't correspond to a single character through the conversion
           from the encoding specified by the encoding pragma.  The escape was
           replaced with REPLACEMENT CHARACTER (U+FFFD) instead, except within
           "(?[   ])", where it is a fatal error.  The <-- HERE shows
           whereabouts in the regular expression the escape was discovered.

       Invalid hexadecimal number in \N{U+...}
       Invalid hexadecimal number in \N{U+...} in regex; marked by <-- HERE in
       m/%s/
           (F) The character constant represented by "..." is not a valid
           hexadecimal number.  Either it is empty, or you tried to use a
           character other than 0 - 9 or A - F, a - f in a hexadecimal number.

       Invalid module name %s with -%c option: contains single ':'
           (F) The module argument to perl's -m and -M command-line options
           cannot contain single colons in the module name, but only in the
           arguments after "=".  In other words, -MFoo::Bar=:baz is ok, but
           -MFoo:Bar=baz is not.

       Invalid mro name: '%s'
           (F) You tried to "mro::set_mro("classname", "foo")" or "use mro
           'foo'", where "foo" is not a valid method resolution order (MRO).
           Currently, the only valid ones supported are "dfs" and "c3", unless
           you have loaded a module that is a MRO plugin.  See mro and
           perlmroapi.

       Invalid negative number (%s) in chr
           (W utf8) You passed a negative number to "chr".  Negative numbers
           are not valid character numbers, so it returns the Unicode
           replacement character (U+FFFD).

       Invalid number '%s' for -C option.
           (F) You supplied a number to the -C option that either has extra
           leading zeroes or overflows perl's unsigned integer representation.

       invalid option -D%c, use -D'' to see choices
           (S debugging) Perl was called with invalid debugger flags.  Call
           perl with the -D option with no flags to see the list of acceptable
           values.  See also "-Dletters" in perlrun.

       Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/
           (F) The pattern looks like a {min,max} quantifier, but the min or
           max could not be parsed as a valid number - either it has leading
           zeroes, or it represents too big a number to cope with.  The
           <-- HERE shows where in the regular expression the problem was
           discovered.  See perlre.

       Invalid [] range "%s" in regex; marked by <-- HERE in m/%s/
           (F) The range specified in a character class had a minimum
           character greater than the maximum character.  One possibility is
           that you forgot the "{}" from your ending "\x{}" - "\x" without the
           curly braces can go only up to "ff".  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.
           See perlre.

       Invalid range "%s" in transliteration operator
           (F) The range specified in the tr/// or y/// operator had a minimum
           character greater than the maximum character.  See perlop.

       Invalid reference to group in regex; marked by <-- HERE in m/%s/
           (F) The capture group you specified can't possibly exist because
           the number you used is not within the legal range of possible
           values for this machine.

       Invalid separator character %s in attribute list
           (F) Something other than a colon or whitespace was seen between the
           elements of an attribute list.  If the previous attribute had a
           parenthesised parameter list, perhaps that list was terminated too
           soon.  See attributes.

       Invalid separator character %s in PerlIO layer specification %s
           (W layer) When pushing layers onto the Perl I/O system, something
           other than a colon or whitespace was seen between the elements of a
           layer list.  If the previous attribute had a parenthesised
           parameter list, perhaps that list was terminated too soon.

       Invalid strict version format (%s)
           (F) A version number did not meet the "strict" criteria for
           versions.  A "strict" version number is a positive decimal number
           (integer or decimal-fraction) without exponentiation or else a
           dotted-decimal v-string with a leading 'v' character and at least
           three components.  The parenthesized text indicates which criteria
           were not met.  See the version module for more details on allowed
           version formats.

       Invalid type '%s' in %s
           (F) The given character is not a valid pack or unpack type.  See
           "pack" in perlfunc.

           (W) The given character is not a valid pack or unpack type but used
           to be silently ignored.

       Invalid version format (%s)
           (F) A version number did not meet the "lax" criteria for versions.
           A "lax" version number is a positive decimal number (integer or
           decimal-fraction) without exponentiation or else a dotted-decimal
           v-string.  If the v-string has fewer than three components, it must
           have a leading 'v' character.  Otherwise, the leading 'v' is
           optional.  Both decimal and dotted-decimal versions may have a
           trailing "alpha" component separated by an underscore character
           after a fractional or dotted-decimal component.  The parenthesized
           text indicates which criteria were not met.  See the version module
           for more details on allowed version formats.

       Invalid version object
           (F) The internal structure of the version object was invalid.
           Perhaps the internals were modified directly in some way or an
           arbitrary reference was blessed into the "version" class.

       In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by
       <-- HERE in m/%s/
       Inverting a character class which contains a multi-character sequence
       is illegal in regex; marked by <-- HERE in m/%s/
           (F) You wrote something like

            qr/\P{name=KATAKANA LETTER AINU P}/
            qr/[^\p{name=KATAKANA LETTER AINU P}]/

           This name actually evaluates to a sequence of two Katakana
           characters, not just a single one, and it is illegal to try to take
           the complement of a sequence.  (Mathematically it would mean any
           sequence of characters from 0 to infinity in length that weren't
           these two in a row, and that is likely not of any real use.)

           (F) The two-character sequence "(*" in this context in a regular
           expression pattern should be an indivisible token, with nothing
           intervening between the "(" and the "*", but you separated them.

       ioctl is not implemented
           (F) Your machine apparently doesn't implement ioctl(), which is
           pretty strange for a machine that supports C.

       ioctl() on unopened %s
           (W unopened) You tried ioctl() on a filehandle that was never
           opened.  Check your control flow and number of arguments.

       IO layers (like '%s') unavailable
           (F) Your Perl has not been configured to have PerlIO, and therefore
           you cannot use IO layers.  To have PerlIO, Perl must be configured
           with 'useperlio'.

       IO::Socket::atmark not implemented on this architecture
           (F) Your machine doesn't implement the sockatmark() functionality,
           neither as a system call nor an ioctl call (SIOCATMARK).

       '%s' is an unknown bound type in regex; marked by <-- HERE in m/%s/
           (F) You used "\b{...}" or "\B{...}" and the "..." is not known to
           Perl.  The current valid ones are given in "\b{}, \b, \B{}, \B" in
           perlrebackslash.

       %s is forbidden - matches null string many times in regex; marked by
       <-- HERE in m/%s/
           (F) The pattern you've specified might cause the regular expression
           to infinite loop so it is forbidden.  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.
           See perlre.

       %s() isn't allowed on :utf8 handles
           (F) The sysread(), recv(), syswrite() and send() operators are not
           allowed on handles that have the ":utf8" layer, either explicitly,
           or implicitly, eg., with the ":encoding(UTF-16LE)" layer.

           Previously sysread() and recv() currently use only the ":utf8" flag
           for the stream, ignoring the actual layers.  Since sysread() and
           recv() did no UTF-8 validation they can end up creating invalidly
           encoded scalars.

           Similarly, syswrite() and send() used only the ":utf8" flag,
           otherwise ignoring any layers.  If the flag is set, both wrote the
           value UTF-8 encoded, even if the layer is some different encoding,
           such as the example above.

           Ideally, all of these operators would completely ignore the ":utf8"
           state, working only with bytes, but this would result in silently
           breaking existing code.

       "%s" is more clearly written simply as "%s" in regex; marked by
       <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'" or within "(?[...])")

           You specified a character that has the given plainer way of writing
           it, and which is also portable to platforms running with different
           character sets.

       $* is no longer supported as of Perl 5.30
           (F) The special variable $*, deprecated in older perls, was removed
           in 5.10.0, is no longer supported and is a fatal error as of Perl
           5.30.  In previous versions of perl the use of $* enabled or
           disabled multi-line matching within a string.

           Instead of using $* you should use the "/m" (and maybe "/s") regexp
           modifiers.  You can enable "/m" for a lexical scope (even a whole
           file) with "use re '/m'".  (In older versions: when $* was set to a
           true value then all regular expressions behaved as if they were
           written using "/m".)

           Use of this variable will be a fatal error in Perl 5.30.

       $# is no longer supported as of Perl 5.30
           (F) The special variable $#, deprecated in older perls, was removed
           as of 5.10.0, is no longer supported and is a fatal error as of
           Perl 5.30.  You should use the printf/sprintf functions instead.

       '%s' is not a code reference
           (W overload) The second (fourth, sixth, ...) argument of
           overload::constant needs to be a code reference.  Either an
           anonymous subroutine, or a reference to a subroutine.

       '%s' is not an overloadable type
           (W overload) You tried to overload a constant type the overload
           package is unaware of.

       isa is experimental
           (S experimental::isa) This warning is emitted if you use the
           ("isa") operator. This operator is currently experimental and its
           behaviour may change in future releases of Perl.

       -i used with no filenames on the command line, reading from STDIN
           (S inplace) The "-i" option was passed on the command line,
           indicating that the script is intended to edit files in place, but
           no files were given.  This is usually a mistake, since editing
           STDIN in place doesn't make sense, and can be confusing because it
           can make perl look like it is hanging when it is really just trying
           to read from STDIN.  You should either pass a filename to edit, or
           remove "-i" from the command line.  See perlrun for more details.

       Junk on end of regexp in regex m/%s/
           (P) The regular expression parser is confused.

       \K not permitted in lookahead/lookbehind in regex; marked by <-- HERE
       in m/%s/
           (F) Your regular expression used "\K" in a lookahead or lookbehind
           assertion, which currently isn't permitted.

           This may change in the future, see Support \K in lookarounds
           <https://github.com/Perl/perl5/issues/18134>.

       Label not found for "last %s"
           (F) You named a loop to break out of, but you're not currently in a
           loop of that name, not even if you count where you were called
           from.  See "last" in perlfunc.

       Label not found for "next %s"
           (F) You named a loop to continue, but you're not currently in a
           loop of that name, not even if you count where you were called
           from.  See "last" in perlfunc.

       Label not found for "redo %s"
           (F) You named a loop to restart, but you're not currently in a loop
           of that name, not even if you count where you were called from.
           See "last" in perlfunc.

       leaving effective %s failed
           (F) While under the "use filetest" pragma, switching the real and
           effective uids or gids failed.

       length/code after end of string in unpack
           (F) While unpacking, the string buffer was already used up when an
           unpack length/code combination tried to obtain more data.  This
           results in an undefined value for the length.  See "pack" in
           perlfunc.

       length() used on %s (did you mean "scalar(%s)"?)
           (W syntax) You used length() on either an array or a hash when you
           probably wanted a count of the items.

           Array size can be obtained by doing:

               scalar(@array);

           The number of items in a hash can be obtained by doing:

               scalar(keys %hash);

       Lexing code attempted to stuff non-Latin-1 character into Latin-1 input
           (F) An extension is attempting to insert text into the current
           parse (using lex_stuff_pvn or similar), but tried to insert a
           character that couldn't be part of the current input.  This is an
           inherent pitfall of the stuffing mechanism, and one of the reasons
           to avoid it.  Where it is necessary to stuff, stuffing only plain
           ASCII is recommended.

       Lexing code internal error (%s)
           (F) Lexing code supplied by an extension violated the lexer's API
           in a detectable way.

       listen() on closed socket %s
           (W closed) You tried to do a listen on a closed socket.  Did you
           forget to check the return value of your socket() call?  See
           "listen" in perlfunc.

       List form of piped open not implemented
           (F) On some platforms, notably Windows, the three-or-more-arguments
           form of "open" does not support pipes, such as "open($pipe, '|-',
           @args)".  Use the two-argument "open($pipe, '|prog arg1 arg2...')"
           form instead.

       Literal vertical space in [] is illegal except under /x in regex;
       marked by <-- HERE in m/%s/
           (F) (only under "use re 'strict'" or within "(?[...])")

           Likely you forgot the "/x" modifier or there was a typo in the
           pattern.  For example, did you really mean to match a form-feed?
           If so, all the ASCII vertical space control characters are
           representable by escape sequences which won't present such a
           jarring appearance as your pattern does when displayed.

             \r    carriage return
             \f    form feed
             \n    line feed
             \cK   vertical tab

       %s: loadable library and perl binaries are mismatched (got handshake
       key %p, needed %p)
           (P) A dynamic loading library ".so" or ".dll" was being loaded into
           the process that was built against a different build of perl than
           the said library was compiled against.  Reinstalling the XS module
           will likely fix this error.

       Locale '%s' contains (at least) the following characters which have
       unexpected meanings: %s  The Perl program will use the expected
       meanings
           (W locale) You are using the named UTF-8 locale.  UTF-8 locales are
           expected to have very particular behavior, which most do.  This
           message arises when perl found some departures from the
           expectations, and is notifying you that the expected behavior
           overrides these differences.  In some cases the differences are
           caused by the locale definition being defective, but the most
           common causes of this warning are when there are ambiguities and
           conflicts in following the Standard, and the locale has chosen an
           approach that differs from Perl's.

           One of these is because that, contrary to the claims, Unicode is
           not completely locale insensitive.  Turkish and some related
           languages have two types of "I" characters.  One is dotted in both
           upper- and lowercase, and the other is dotless in both cases.
           Unicode allows a locale to use either the Turkish rules, or the
           rules used in all other instances, where there is only one type of
           "I", which is dotless in the uppercase, and dotted in the lower.
           The perl core does not (yet) handle the Turkish case, and this
           message warns you of that.  Instead, the Unicode::Casing module
           allows you to mostly implement the Turkish casing rules.

           The other common cause is for the characters

            $ + < = > ^ ` | ~

           These are problematic.  The C standard says that these should be
           considered punctuation in the C locale (and the POSIX standard
           defers to the C standard), and Unicode is generally considered a
           superset of the C locale.  But Unicode has added an extra category,
           "Symbol", and classifies these particular characters as being
           symbols.  Most UTF-8 locales have them treated as punctuation, so
           that ispunct(2) returns non-zero for them.  But a few locales have
           it return 0.   Perl takes the first approach, not using "ispunct()"
           at all (see Note [5] in perlrecharclass), and this message is
           raised to notify you that you are getting Perl's approach, not the
           locale's.

       Locale '%s' may not work well.%s
           (W locale) You are using the named locale, which is a non-UTF-8
           one, and which perl has determined is not fully compatible with
           what it can handle.  The second %s gives a reason.

           By far the most common reason is that the locale has characters in
           it that are represented by more than one byte.  The only such
           locales that Perl can handle are the UTF-8 locales.  Most likely
           the specified locale is a non-UTF-8 one for an East Asian language
           such as Chinese or Japanese.  If the locale is a superset of ASCII,
           the ASCII portion of it may work in Perl.

           Some essentially obsolete locales that aren't supersets of ASCII,
           mainly those in ISO 646 or other 7-bit locales, such as ASMO 449,
           can also have problems, depending on what portions of the ASCII
           character set get changed by the locale and are also used by the
           program.  The warning message lists the determinable conflicting
           characters.

           Note that not all incompatibilities are found.

           If this happens to you, there's not much you can do except switch
           to use a different locale or use Encode to translate from the
           locale into UTF-8; if that's impracticable, you have been warned
           that some things may break.

           This message is output once each time a bad locale is switched into
           within the scope of "use locale", or on the first possibly-affected
           operation if the "use locale" inherits a bad one.  It is not raised
           for any operations from the POSIX module.

       localtime(%f) failed
           (W overflow) You called "localtime" with a number that it could not
           handle: too large, too small, or NaN.  The returned value is
           "undef".

       localtime(%f) too large
           (W overflow) You called "localtime" with a number that was larger
           than it can reliably handle and "localtime" probably returned the
           wrong date.  This warning is also triggered with NaN (the special
           not-a-number value).

       localtime(%f) too small
           (W overflow) You called "localtime" with a number that was smaller
           than it can reliably handle and "localtime" probably returned the
           wrong date.

       Lookbehind longer than %d not implemented in regex m/%s/
           (F) There is currently a limit on the length of string which
           lookbehind can handle.  This restriction may be eased in a future
           release.

       Lost precision when %s %f by 1
           (W imprecision) You attempted to increment or decrement a value by
           one, but the result is too large for the underlying floating point
           representation to store accurately. Hence, the target of "++" or
           "--" is increased or decreased by quite different value than one,
           such as zero (i.e. the target is unchanged) or two, due to
           rounding.  Perl issues this warning because it has already switched
           from integers to floating point when values are too large for
           integers, and now even floating point is insufficient.  You may
           wish to switch to using Math::BigInt explicitly.

       lstat() on filehandle%s
           (W io) You tried to do an lstat on a filehandle.  What did you mean
           by that?  lstat() makes sense only on filenames.  (Perl did a
           fstat() instead on the filehandle.)

       lvalue attribute %s already-defined subroutine
           (W misc) Although attributes.pm allows this, turning the lvalue
           attribute on or off on a Perl subroutine that is already defined
           does not always work properly.  It may or may not do what you want,
           depending on what code is inside the subroutine, with exact details
           subject to change between Perl versions.  Only do this if you
           really know what you are doing.

       lvalue attribute ignored after the subroutine has been defined
           (W misc) Using the ":lvalue" declarative syntax to make a Perl
           subroutine an lvalue subroutine after it has been defined is not
           permitted.  To make the subroutine an lvalue subroutine, add the
           lvalue attribute to the definition, or put the "sub foo :lvalue;"
           declaration before the definition.

           See also attributes.pm.

       Magical list constants are not supported
           (F) You assigned a magical array to a stash element, and then tried
           to use the subroutine from the same slot.  You are asking Perl to
           do something it cannot do, details subject to change between Perl
           versions.

       Malformed integer in [] in pack
           (F) Between the brackets enclosing a numeric repeat count only
           digits are permitted.  See "pack" in perlfunc.

       Malformed integer in [] in unpack
           (F) Between the brackets enclosing a numeric repeat count only
           digits are permitted.  See "pack" in perlfunc.

       Malformed PERLLIB_PREFIX
           (F) An error peculiar to OS/2.  PERLLIB_PREFIX should be of the
           form

               prefix1;prefix2

           or
               prefix1 prefix2

           with nonempty prefix1 and prefix2.  If "prefix1" is indeed a prefix
           of a builtin library search path, prefix2 is substituted.  The
           error may appear if components are not found, or are too long.  See
           "PERLLIB_PREFIX" in perlos2.

       Malformed prototype for %s: %s
           (F) You tried to use a function with a malformed prototype.  The
           syntax of function prototypes is given a brief compile-time check
           for obvious errors like invalid characters.  A more rigorous check
           is run when the function is called.  Perhaps the function's author
           was trying to write a subroutine signature but didn't enable that
           feature first ("use feature 'signatures'"), so the signature was
           instead interpreted as a bad prototype.

       Malformed UTF-8 character%s
           (S utf8)(F) Perl detected a string that should be UTF-8, but didn't
           comply with UTF-8 encoding rules, or represents a code point whose
           ordinal integer value doesn't fit into the word size of the current
           platform (overflows).  Details as to the exact malformation are
           given in the variable, %s, part of the message.

           One possible cause is that you set the UTF8 flag yourself for data
           that you thought to be in UTF-8 but it wasn't (it was for example
           legacy 8-bit data).  To guard against this, you can use
           "Encode::decode('UTF-8', ...)".

           If you use the ":encoding(UTF-8)" PerlIO layer for input, invalid
           byte sequences are handled gracefully, but if you use ":utf8", the
           flag is set without validating the data, possibly resulting in this
           error message.

           See also "Handling Malformed Data" in Encode.

       Malformed UTF-8 returned by \N{%s} immediately after '%s'
           (F) The charnames handler returned malformed UTF-8.

       Malformed UTF-8 string in "%s"
           (F) This message indicates a bug either in the Perl core or in XS
           code. Such code was trying to find out if a character, allegedly
           stored internally encoded as UTF-8, was of a given type, such as
           being punctuation or a digit.  But the character was not encoded in
           legal UTF-8.  The %s is replaced by a string that can be used by
           knowledgeable people to determine what the type being checked
           against was.

           Passing malformed strings was deprecated in Perl 5.18, and became
           fatal in Perl 5.26.

       Malformed UTF-8 string in '%c' format in unpack
           (F) You tried to unpack something that didn't comply with UTF-8
           encoding rules and perl was unable to guess how to make more
           progress.

       Malformed UTF-8 string in pack
           (F) You tried to pack something that didn't comply with UTF-8
           encoding rules and perl was unable to guess how to make more
           progress.

       Malformed UTF-8 string in unpack
           (F) You tried to unpack something that didn't comply with UTF-8
           encoding rules and perl was unable to guess how to make more
           progress.

       Malformed UTF-16 surrogate
           (F) Perl thought it was reading UTF-16 encoded character data but
           while doing it Perl met a malformed Unicode surrogate.

       Mandatory parameter follows optional parameter
           (F) In a subroutine signature, you wrote something like "$a =
           undef, $b", making an earlier parameter optional and a later one
           mandatory.  Parameters are filled from left to right, so it's
           impossible for the caller to omit an earlier one and pass a later
           one.  If you want to act as if the parameters are filled from right
           to left, declare the rightmost optional and then shuffle the
           parameters around in the subroutine's body.

       Matched non-Unicode code point 0x%X against Unicode property; may not
       be portable
           (S non_unicode) Perl allows strings to contain a superset of
           Unicode code points; each code point may be as large as what is
           storable in a signed integer on your system, but these may not be
           accepted by other languages/systems.  This message occurs when you
           matched a string containing such a code point against a regular
           expression pattern, and the code point was matched against a
           Unicode property, "\p{...}" or "\P{...}".  Unicode properties are
           only defined on Unicode code points, so the result of this match is
           undefined by Unicode, but Perl (starting in v5.20) treats non-
           Unicode code points as if they were typical unassigned Unicode
           ones, and matched this one accordingly.  Whether a given property
           matches these code points or not is specified in "Properties
           accessible through \p{} and \P{}" in perluniprops.

           This message is suppressed (unless it has been made fatal) if it is
           immaterial to the results of the match if the code point is Unicode
           or not.  For example, the property "\p{ASCII_Hex_Digit}" only can
           match the 22 characters "[0-9A-Fa-f]", so obviously all other code
           points, Unicode or not, won't match it.  (And "\P{ASCII_Hex_Digit}"
           will match every code point except these 22.)

           Getting this message indicates that the outcome of the match
           arguably should have been the opposite of what actually happened.
           If you think that is the case, you may wish to make the
           "non_unicode" warnings category fatal; if you agree with Perl's
           decision, you may wish to turn off this category.

           See "Beyond Unicode code points" in perlunicode for more
           information.

       %s matches null string many times in regex; marked by <-- HERE in m/%s/
           (W regexp) The pattern you've specified would be an infinite loop
           if the regular expression engine didn't specifically check for
           that.  The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Maximal count of pending signals (%u) exceeded
           (F) Perl aborted due to too high a number of signals pending.  This
           usually indicates that your operating system tried to deliver
           signals too fast (with a very high priority), starving the perl
           process from resources it would need to reach a point where it can
           process signals safely.  (See "Deferred Signals (Safe Signals)" in
           perlipc.)

       "%s" may clash with future reserved word
           (W) This warning may be due to running a perl5 script through a
           perl4 interpreter, especially if the word that is being warned
           about is "use" or "my".

       '%' may not be used in pack
           (F) You can't pack a string by supplying a checksum, because the
           checksumming process loses information, and you can't go the other
           way.  See "unpack" in perlfunc.

       Method for operation %s not found in package %s during blessing
           (F) An attempt was made to specify an entry in an overloading table
           that doesn't resolve to a valid subroutine.  See overload.

       Method %s not permitted
           See "500 Server error".

       Might be a runaway multi-line %s string starting on line %d
           (S) An advisory indicating that the previous error may have been
           caused by a missing delimiter on a string or pattern, because it
           eventually ended earlier on the current line.

       Misplaced _ in number
           (W syntax) An underscore (underbar) in a numeric constant did not
           separate two digits.

       Missing argument for %n in %s
           (F) A %n was used in a format string with no corresponding argument
           for perl to write the current string length to.

       Missing argument in %s
           (W missing) You called a function with fewer arguments than other
           arguments you supplied indicated would be needed.

           Currently only emitted when a printf-type format required more
           arguments than were supplied, but might be used in the future for
           other cases where we can statically determine that arguments to
           functions are missing, e.g. for the "pack" in perlfunc function.

       Missing argument to -%c
           (F) The argument to the indicated command line switch must follow
           immediately after the switch, without intervening spaces.

       Missing braces on \N{}
       Missing braces on \N{} in regex; marked by <-- HERE in m/%s/
           (F) Wrong syntax of character name literal "\N{charname}" within
           double-quotish context.  This can also happen when there is a space
           (or comment) between the "\N" and the "{" in a regex with the "/x"
           modifier.  This modifier does not change the requirement that the
           brace immediately follow the "\N".

       Missing braces on \o{}
           (F) A "\o" must be followed immediately by a "{" in double-quotish
           context.

       Missing comma after first argument to %s function
           (F) While certain functions allow you to specify a filehandle or an
           "indirect object" before the argument list, this ain't one of them.

       Missing command in piped open
           (W pipe) You used the "open(FH, "| command")" or "open(FH, "command
           |")" construction, but the command was missing or blank.

       Missing control char name in \c
           (F) A double-quoted string ended with "\c", without the required
           control character name.

       Missing ']' in prototype for %s : %s
           (W illegalproto) A grouping was started with "[" but never closed
           with "]".

       Missing name in "%s sub"
           (F) The syntax for lexically scoped subroutines requires that they
           have a name with which they can be found.

       Missing $ on loop variable
           (F) Apparently you've been programming in csh too much.  Variables
           are always mentioned with the $ in Perl, unlike in the shells,
           where it can vary from one line to the next.

       (Missing operator before %s?)
           (S syntax) This is an educated guess made in conjunction with the
           message "%s found where operator expected".  Often the missing
           operator is a comma.

       Missing or undefined argument to %s
           (F) You tried to call require or do with no argument or with an
           undefined value as an argument.  Require expects either a package
           name or a file-specification as an argument; do expects a filename.
           See "require EXPR" in perlfunc and "do EXPR" in perlfunc.

       Missing right brace on \%c{} in regex; marked by <-- HERE in m/%s/
           (F) Missing right brace in "\x{...}", "\p{...}", "\P{...}", or
           "\N{...}".

       Missing right brace on \N{}
       Missing right brace on \N{} or unescaped left brace after \N
           (F) "\N" has two meanings.

           The traditional one has it followed by a name enclosed in braces,
           meaning the character (or sequence of characters) given by that
           name.  Thus "\N{ASTERISK}" is another way of writing "*", valid in
           both double-quoted strings and regular expression patterns.  In
           patterns, it doesn't have the meaning an unescaped "*" does.

           Starting in Perl 5.12.0, "\N" also can have an additional meaning
           (only) in patterns, namely to match a non-newline character.  (This
           is short for "[^\n]", and like "." but is not affected by the "/s"
           regex modifier.)

           This can lead to some ambiguities.  When "\N" is not followed
           immediately by a left brace, Perl assumes the "[^\n]" meaning.
           Also, if the braces form a valid quantifier such as "\N{3}" or
           "\N{5,}", Perl assumes that this means to match the given quantity
           of non-newlines (in these examples, 3; and 5 or more,
           respectively).  In all other case, where there is a "\N{" and a
           matching "}", Perl assumes that a character name is desired.

           However, if there is no matching "}", Perl doesn't know if it was
           mistakenly omitted, or if "[^\n]{" was desired, and raises this
           error.  If you meant the former, add the right brace; if you meant
           the latter, escape the brace with a backslash, like so: "\N\{"

       Missing right curly or square bracket
           (F) The lexer counted more opening curly or square brackets than
           closing ones.  As a general rule, you'll find it's missing near the
           place you were last editing.

       (Missing semicolon on previous line?)
           (S syntax) This is an educated guess made in conjunction with the
           message "%s found where operator expected".  Don't automatically
           put a semicolon on the previous line just because you saw this
           message.

       Modification of a read-only value attempted
           (F) You tried, directly or indirectly, to change the value of a
           constant.  You didn't, of course, try "2 = 1", because the compiler
           catches that.  But an easy way to do the same thing is:

               sub mod { $_[0] = 1 }
               mod(2);

           Another way is to assign to a substr() that's off the end of the
           string.

           Yet another way is to assign to a "foreach" loop VAR when VAR is
           aliased to a constant in the look LIST:

               $x = 1;
               foreach my $n ($x, 2) {
                   $n *= 2; # modifies the $x, but fails on attempt to
               }            # modify the 2

           PerlIO::scalar will also produce this message as a warning if you
           attempt to open a read-only scalar for writing.

       Modification of non-creatable array value attempted, %s
           (F) You tried to make an array value spring into existence, and the
           subscript was probably negative, even counting from end of the
           array backwards.

       Modification of non-creatable hash value attempted, %s
           (P) You tried to make a hash value spring into existence, and it
           couldn't be created for some peculiar reason.

       Module name must be constant
           (F) Only a bare module name is allowed as the first argument to a
           "use".

       Module name required with -%c option
           (F) The "-M" or "-m" options say that Perl should load some module,
           but you omitted the name of the module.  Consult perlrun for full
           details about "-M" and "-m".

       More than one argument to '%s' open
           (F) The "open" function has been asked to open multiple files.
           This can happen if you are trying to open a pipe to a command that
           takes a list of arguments, but have forgotten to specify a piped
           open mode.  See "open" in perlfunc for details.

       mprotect for COW string %p %u failed with %d
           (S) You compiled perl with -DPERL_DEBUG_READONLY_COW (see "Copy on
           Write" in perlguts), but a shared string buffer could not be made
           read-only.

       mprotect for %p %u failed with %d
           (S) You compiled perl with -DPERL_DEBUG_READONLY_OPS (see
           perlhacktips), but an op tree could not be made read-only.

       mprotect RW for COW string %p %u failed with %d
           (S) You compiled perl with -DPERL_DEBUG_READONLY_COW (see "Copy on
           Write" in perlguts), but a read-only shared string buffer could not
           be made mutable.

       mprotect RW for %p %u failed with %d
           (S) You compiled perl with -DPERL_DEBUG_READONLY_OPS (see
           perlhacktips), but a read-only op tree could not be made mutable
           before freeing the ops.

       msg%s not implemented
           (F) You don't have System V message IPC on your system.

       Multidimensional hash lookup is disabled
           (F) You supplied a list of subscripts to a hash lookup under "no
           feature "multidimensional";", eg:

             $z = $foo{$x, $y};

           which by default acts like:

             $z = $foo{join($;, $x, $y)};

       Multidimensional syntax %s not supported
           (W syntax) Multidimensional arrays aren't written like $foo[1,2,3].
           They're written like $foo[1][2][3], as in C.

       Multiple slurpy parameters not allowed
           (F) In subroutine signatures, a slurpy parameter ("@" or "%") must
           be the last parameter, and there must not be more than one of them;
           for example:

               sub foo ($a, @b)    {} # legal
               sub foo ($a, @b, %) {} # invalid

       '/' must follow a numeric type in unpack
           (F) You had an unpack template that contained a '/', but this did
           not follow some unpack specification producing a numeric value.
           See "pack" in perlfunc.

       %s must not be a named sequence in transliteration operator
           (F) Transliteration ("tr///" and "y///") transliterates individual
           characters.  But a named sequence by definition is more than an
           individual character, and hence doing this operation on it doesn't
           make sense.

       "my sub" not yet implemented
           (F) Lexically scoped subroutines are not yet implemented.  Don't
           try that yet.

       "my" subroutine %s can't be in a package
           (F) Lexically scoped subroutines aren't in a package, so it doesn't
           make sense to try to declare one with a package qualifier on the
           front.

       "my %s" used in sort comparison
           (W syntax) The package variables $a and $b are used for sort
           comparisons.  You used $a or $b in as an operand to the "<=>" or
           "cmp" operator inside a sort comparison block, and the variable had
           earlier been declared as a lexical variable.  Either qualify the
           sort variable with the package name, or rename the lexical
           variable.

       "my" variable %s can't be in a package
           (F) Lexically scoped variables aren't in a package, so it doesn't
           make sense to try to declare one with a package qualifier on the
           front.  Use local() if you want to localize a package variable.

       Name "%s::%s" used only once: possible typo
           (W once) Typographical errors often show up as unique variable
           names.  If you had a good reason for having a unique name, then
           just mention it again somehow to suppress the message.  The "our"
           declaration is also provided for this purpose.

           NOTE: This warning detects package symbols that have been used only
           once.  This means lexical variables will never trigger this
           warning.  It also means that all of the package variables $c, @c,
           %c, as well as *c, &c, sub c{}, c(), and c (the filehandle or
           format) are considered the same; if a program uses $c only once but
           also uses any of the others it will not trigger this warning.
           Symbols beginning with an underscore and symbols using special
           identifiers (q.v. perldata) are exempt from this warning.

       Need exactly 3 octal digits in regex; marked by <-- HERE in m/%s/
           (F) Within "(?[   ])", all constants interpreted as octal need to
           be exactly 3 digits long.  This helps catch some ambiguities.  If
           your constant is too short, add leading zeros, like

            (?[ [ \078 ] ])     # Syntax error!
            (?[ [ \0078 ] ])    # Works
            (?[ [ \007 8 ] ])   # Clearer

           The maximum number this construct can express is "\777".  If you
           need a larger one, you need to use \o{} instead.  If you meant two
           separate things, you need to separate them:

            (?[ [ \7776 ] ])        # Syntax error!
            (?[ [ \o{7776} ] ])     # One meaning
            (?[ [ \777 6 ] ])       # Another meaning
            (?[ [ \777 \006 ] ])    # Still another

       Negative '/' count in unpack
           (F) The length count obtained from a length/code unpack operation
           was negative.  See "pack" in perlfunc.

       Negative length
           (F) You tried to do a read/write/send/recv operation with a buffer
           length that is less than 0.  This is difficult to imagine.

       Negative offset to vec in lvalue context
           (F) When "vec" is called in an lvalue context, the second argument
           must be greater than or equal to zero.

       Negative repeat count does nothing
           (W numeric) You tried to execute the "x" repetition operator fewer
           than 0 times, which doesn't make sense.

       Nested quantifiers in regex; marked by <-- HERE in m/%s/
           (F) You can't quantify a quantifier without intervening
           parentheses.  So things like ** or +* or ?* are illegal.  The
           <-- HERE shows whereabouts in the regular expression the problem
           was discovered.

           Note that the minimal matching quantifiers, "*?", "+?", and "??"
           appear to be nested quantifiers, but aren't.  See perlre.

       %s never introduced
           (S internal) The symbol in question was declared but somehow went
           out of scope before it could possibly have been used.

       next::method/next::can/maybe::next::method cannot find enclosing method
           (F) "next::method" needs to be called within the context of a real
           method in a real package, and it could not find such a context.
           See mro.

       \N in a character class must be a named character: \N{...} in regex;
       marked by <-- HERE in m/%s/
           (F) The new (as of Perl 5.12) meaning of "\N" as "[^\n]" is not
           valid in a bracketed character class, for the same reason that "."
           in a character class loses its specialness: it matches almost
           everything, which is probably not what you want.

       \N{} here is restricted to one character in regex; marked by <-- HERE
       in m/%s/
           (F) Named Unicode character escapes ("\N{...}") may return a multi-
           character sequence.  Even though a character class is supposed to
           match just one character of input, perl will match the whole thing
           correctly, except under certain conditions.  These currently are

           When the class is inverted ("[^...]")
               The mathematically logical behavior for what matches when
               inverting is very different from what people expect, so we have
               decided to forbid it.

           The escape is the beginning or final end point of a range
               Similarly unclear is what should be generated when the
               "\N{...}" is used as one of the end points of the range, such
               as in

                [\x{41}-\N{ARABIC SEQUENCE YEH WITH HAMZA ABOVE WITH AE}]

               What is meant here is unclear, as the "\N{...}" escape is a
               sequence of code points, so this is made an error.

           In a regex set
               The syntax "(?[   ])" in a regular expression yields a list of
               single code points, none can be a sequence.

       No %s allowed while running setuid
           (F) Certain operations are deemed to be too insecure for a setuid
           or setgid script to even be allowed to attempt.  Generally speaking
           there will be another way to do what you want that is, if not
           secure, at least securable.  See perlsec.

       No code specified for -%c
           (F) Perl's -e and -E command-line options require an argument.  If
           you want to run an empty program, pass the empty string as a
           separate argument or run a program consisting of a single 0 or 1:

               perl -e ""
               perl -e0
               perl -e1

       No comma allowed after %s
           (F) A list operator that has a filehandle or "indirect object" is
           not allowed to have a comma between that and the following
           arguments.  Otherwise it'd be just another one of the arguments.

           One possible cause for this is that you expected to have imported a
           constant to your name space with use or import while no such
           importing took place, it may for example be that your operating
           system does not support that particular constant.  Hopefully you
           did use an explicit import list for the constants you expect to
           see; please see "use" in perlfunc and "import" in perlfunc.  While
           an explicit import list would probably have caught this error
           earlier it naturally does not remedy the fact that your operating
           system still does not support that constant.  Maybe you have a typo
           in the constants of the symbol import list of use or import or in
           the constant name at the line where this error was triggered?

       No command into which to pipe on command line
           (F) An error peculiar to VMS.  Perl handles its own command line
           redirection, and found a '|' at the end of the command line, so it
           doesn't know where you want to pipe the output from this command.

       No DB::DB routine defined
           (F) The currently executing code was compiled with the -d switch,
           but for some reason the current debugger (e.g. perl5db.pl or a
           "Devel::" module) didn't define a routine to be called at the
           beginning of each statement.

       No dbm on this machine
           (P) This is counted as an internal error, because every machine
           should supply dbm nowadays, because Perl comes with SDBM.  See
           SDBM_File.

       No DB::sub routine defined
           (F) The currently executing code was compiled with the -d switch,
           but for some reason the current debugger (e.g. perl5db.pl or a
           "Devel::" module) didn't define a "DB::sub" routine to be called at
           the beginning of each ordinary subroutine call.

       No digits found for %s literal
           (F) No hexadecimal digits were found following "0x" or no binary
           digits were found following "0b".

       No directory specified for -I
           (F) The -I command-line switch requires a directory name as part of
           the same argument.  Use -Ilib, for instance.  -I lib won't work.

       No error file after 2> or 2>> on command line
           (F) An error peculiar to VMS.  Perl handles its own command line
           redirection, and found a '2>' or a '2>>' on the command line, but
           can't find the name of the file to which to write data destined for
           stderr.

       No group ending character '%c' found in template
           (F) A pack or unpack template has an opening '(' or '[' without its
           matching counterpart.  See "pack" in perlfunc.

       No input file after < on command line
           (F) An error peculiar to VMS.  Perl handles its own command line
           redirection, and found a '<' on the command line, but can't find
           the name of the file from which to read data for stdin.

       No next::method '%s' found for %s
           (F) "next::method" found no further instances of this method name
           in the remaining packages of the MRO of this class.  If you don't
           want it throwing an exception, use "maybe::next::method" or
           "next::can".  See mro.

       Non-finite repeat count does nothing
           (W numeric) You tried to execute the "x" repetition operator "Inf"
           (or "-Inf") or "NaN" times, which doesn't make sense.

       Non-hex character in regex; marked by <-- HERE in m/%s/
           (F) In a regular expression, there was a non-hexadecimal character
           where a hex one was expected, like

            (?[ [ \xDG ] ])
            (?[ [ \x{DEKA} ] ])

       Non-hex character '%c' terminates \x early.  Resolved as "%s"
           (W digit) In parsing a hexadecimal numeric constant, a character
           was unexpectedly encountered that isn't hexadecimal.  The resulting
           value is as indicated.

           Note that, within braces, every character starting with the first
           non-hexadecimal up to the ending brace is ignored.

       Non-octal character in regex; marked by <-- HERE in m/%s/
           (F) In a regular expression, there was a non-octal character where
           an octal one was expected, like

            (?[ [ \o{1278} ] ])

       Non-octal character '%c' terminates \o early.  Resolved as "%s"
           (W digit) In parsing an octal numeric constant, a character was
           unexpectedly encountered that isn't octal.  The resulting value is
           as indicated.

           When not using "\o{...}", you wrote something like "\08", or "\179"
           in a double-quotish string.  The resolution is as indicated, with
           all but the last digit treated as a single character, specified in
           octal.  The last digit is the next character in the string.  To
           tell Perl that this is indeed what you want, you can use the "\o{
           }" syntax, or use exactly three digits to specify the octal for the
           character.

           Note that, within braces, every character starting with the first
           non-octal up to the ending brace is ignored.

       "no" not allowed in expression
           (F) The "no" keyword is recognized and executed at compile time,
           and returns no useful value.  See perlmod.

       Non-string passed as bitmask
           (W misc) A number has been passed as a bitmask argument to
           select().  Use the vec() function to construct the file descriptor
           bitmasks for select.  See "select" in perlfunc.

       No output file after > on command line
           (F) An error peculiar to VMS.  Perl handles its own command line
           redirection, and found a lone '>' at the end of the command line,
           so it doesn't know where you wanted to redirect stdout.

       No output file after > or >> on command line
           (F) An error peculiar to VMS.  Perl handles its own command line
           redirection, and found a '>' or a '>>' on the command line, but
           can't find the name of the file to which to write data destined for
           stdout.

       No package name allowed for subroutine %s in "our"
       No package name allowed for variable %s in "our"
           (F) Fully qualified subroutine and variable names are not allowed
           in "our" declarations, because that doesn't make much sense under
           existing rules.  Such syntax is reserved for future extensions.

       No Perl script found in input
           (F) You called "perl -x", but no line was found in the file
           beginning with #! and containing the word "perl".

       No setregid available
           (F) Configure didn't find anything resembling the setregid() call
           for your system.

       No setreuid available
           (F) Configure didn't find anything resembling the setreuid() call
           for your system.

       No such class %s
           (F) You provided a class qualifier in a "my", "our" or "state"
           declaration, but this class doesn't exist at this point in your
           program.

       No such class field "%s" in variable %s of type %s
           (F) You tried to access a key from a hash through the indicated
           typed variable but that key is not allowed by the package of the
           same type.  The indicated package has restricted the set of allowed
           keys using the fields pragma.

       No such hook: %s
           (F) You specified a signal hook that was not recognized by Perl.
           Currently, Perl accepts "__DIE__" and "__WARN__" as valid signal
           hooks.

       No such pipe open
           (P) An error peculiar to VMS.  The internal routine my_pclose()
           tried to close a pipe which hadn't been opened.  This should have
           been caught earlier as an attempt to close an unopened filehandle.

       No such signal: SIG%s
           (W signal) You specified a signal name as a subscript to %SIG that
           was not recognized.  Say "kill -l" in your shell to see the valid
           signal names on your system.

       No Unicode property value wildcard matches:
           (W regexp) You specified a wildcard for a Unicode property value,
           but there is no property value in the current Unicode release that
           matches it.  Check your spelling.

       Not a CODE reference
           (F) Perl was trying to evaluate a reference to a code value (that
           is, a subroutine), but found a reference to something else instead.
           You can use the ref() function to find out what kind of ref it
           really was.  See also perlref.

       Not a GLOB reference
           (F) Perl was trying to evaluate a reference to a "typeglob" (that
           is, a symbol table entry that looks like *foo), but found a
           reference to something else instead.  You can use the ref()
           function to find out what kind of ref it really was.  See perlref.

       Not a HASH reference
           (F) Perl was trying to evaluate a reference to a hash value, but
           found a reference to something else instead.  You can use the ref()
           function to find out what kind of ref it really was.  See perlref.

       '#' not allowed immediately following a sigil in a subroutine signature
           (F) In a subroutine signature definition, a comment following a
           sigil ("$", "@" or "%"), needs to be separated by whitespace or a
           comma etc., in particular to avoid confusion with the $# variable.
           For example:

               # bad
               sub f ($# ignore first arg
                      , $b) {}
               # good
               sub f ($, # ignore first arg
                      $b) {}

       Not an ARRAY reference
           (F) Perl was trying to evaluate a reference to an array value, but
           found a reference to something else instead.  You can use the ref()
           function to find out what kind of ref it really was.  See perlref.

       Not a SCALAR reference
           (F) Perl was trying to evaluate a reference to a scalar value, but
           found a reference to something else instead.  You can use the ref()
           function to find out what kind of ref it really was.  See perlref.

       Not a subroutine reference
           (F) Perl was trying to evaluate a reference to a code value (that
           is, a subroutine), but found a reference to something else instead.
           You can use the ref() function to find out what kind of ref it
           really was.  See also perlref.

       Not a subroutine reference in overload table
           (F) An attempt was made to specify an entry in an overloading table
           that doesn't somehow point to a valid subroutine.  See overload.

       Not enough arguments for %s
           (F) The function requires more arguments than you specified.

       Not enough format arguments
           (W syntax) A format specified more picture fields than the next
           line supplied.  See perlform.

       %s: not found
           (A) You've accidentally run your script through the Bourne shell
           instead of Perl.  Check the #! line, or manually feed your script
           into Perl yourself.

       no UTC offset information; assuming local time is UTC
           (S) A warning peculiar to VMS.  Perl was unable to find the local
           timezone offset, so it's assuming that local system time is
           equivalent to UTC.  If it's not, define the logical name
           SYS$TIMEZONE_DIFFERENTIAL to translate to the number of seconds
           which need to be added to UTC to get local time.

       NULL OP IN RUN
           (S debugging) Some internal routine called run() with a null opcode
           pointer.

       Null picture in formline
           (F) The first argument to formline must be a valid format picture
           specification.  It was found to be empty, which probably means you
           supplied it an uninitialized value.  See perlform.

       Null realloc
           (P) An attempt was made to realloc NULL.

       NULL regexp argument
           (P) The internal pattern matching routines blew it big time.

       NULL regexp parameter
           (P) The internal pattern matching routines are out of their gourd.

       Number too long
           (F) Perl limits the representation of decimal numbers in programs
           to about 250 characters.  You've exceeded that length.  Future
           versions of Perl are likely to eliminate this arbitrary limitation.
           In the meantime, try using scientific notation (e.g. "1e6" instead
           of "1_000_000").

       Number with no digits
           (F) Perl was looking for a number but found nothing that looked
           like a number.  This happens, for example with "\o{}", with no
           number between the braces.

       Numeric format result too large
           (F) The length of the result of a numeric format supplied to
           sprintf() or printf() would have been too large for the underlying
           C function to report.  This limit is typically 2GB.

       Numeric variables with more than one digit may not start with '0'
           (F) The only numeric variable which is allowed to start with a 0 is
           $0, and you mentioned a variable that starts with 0 that has more
           than one digit. You probably want to remove the leading 0, or if
           the intent was to express a variable name in octal you should
           convert to decimal.

       Octal number > 037777777777 non-portable
           (W portable) The octal number you specified is larger than 2**32-1
           (4294967295) and therefore non-portable between systems.  See
           perlport for more on portability concerns.

       Odd name/value argument for subroutine '%s'
           (F) A subroutine using a slurpy hash parameter in its signature
           received an odd number of arguments to populate the hash.  It
           requires the arguments to be paired, with the same number of keys
           as values.  The caller of the subroutine is presumably at fault.

           The message attempts to include the name of the called subroutine.
           If the subroutine has been aliased, the subroutine's original name
           will be shown, regardless of what name the caller used.

       Odd number of arguments for overload::constant
           (W overload) The call to overload::constant contained an odd number
           of arguments.  The arguments should come in pairs.

       Odd number of elements in anonymous hash
           (W misc) You specified an odd number of elements to initialize a
           hash, which is odd, because hashes come in key/value pairs.

       Odd number of elements in hash assignment
           (W misc) You specified an odd number of elements to initialize a
           hash, which is odd, because hashes come in key/value pairs.

       Offset outside string
           (F)(W layer) You tried to do a read/write/send/recv/seek operation
           with an offset pointing outside the buffer.  This is difficult to
           imagine.  The sole exceptions to this are that zero padding will
           take place when going past the end of the string when either
           "sysread()"ing a file, or when seeking past the end of a scalar
           opened for I/O (in anticipation of future reads and to imitate the
           behavior with real files).

       Old package separator used in string
           (W syntax) You used the old package separator, "'", in a variable
           named inside a double-quoted string; e.g., "In $name's house".
           This is equivalent to "In $name::s house".  If you meant the
           former, put a backslash before the apostrophe ("In $name\'s
           house").

       %s() on unopened %s
           (W unopened) An I/O operation was attempted on a filehandle that
           was never initialized.  You need to do an open(), a sysopen(), or a
           socket() call, or call a constructor from the FileHandle package.

       -%s on unopened filehandle %s
           (W unopened) You tried to invoke a file test operator on a
           filehandle that isn't open.  Check your control flow.  See also
           "-X" in perlfunc.

       oops: oopsAV
           (S internal) An internal warning that the grammar is screwed up.

       oops: oopsHV
           (S internal) An internal warning that the grammar is screwed up.

       Operand with no preceding operator in regex; marked by <-- HERE in
       m/%s/
           (F) You wrote something like

            (?[ \p{Digit} \p{Thai} ])

           There are two operands, but no operator giving how you want to
           combine them.

       Operation "%s": no method found, %s
           (F) An attempt was made to perform an overloaded operation for
           which no handler was defined.  While some handlers can be
           autogenerated in terms of other handlers, there is no default
           handler for any operation, unless the "fallback" overloading key is
           specified to be true.  See overload.

       Operation "%s" returns its argument for non-Unicode code point 0x%X
           (S non_unicode) You performed an operation requiring Unicode rules
           on a code point that is not in Unicode, so what it should do is not
           defined.  Perl has chosen to have it do nothing, and warn you.

           If the operation shown is "ToFold", it means that case-insensitive
           matching in a regular expression was done on the code point.

           If you know what you are doing you can turn off this warning by "no
           warnings 'non_unicode';".

       Operation "%s" returns its argument for UTF-16 surrogate U+%X
           (S surrogate) You performed an operation requiring Unicode rules on
           a Unicode surrogate.  Unicode frowns upon the use of surrogates for
           anything but storing strings in UTF-16, but rules are (reluctantly)
           defined for the surrogates, and they are to do nothing for this
           operation.  Because the use of surrogates can be dangerous, Perl
           warns.

           If the operation shown is "ToFold", it means that case-insensitive
           matching in a regular expression was done on the code point.

           If you know what you are doing you can turn off this warning by "no
           warnings 'surrogate';".

       Operator or semicolon missing before %s
           (S ambiguous) You used a variable or subroutine call where the
           parser was expecting an operator.  The parser has assumed you
           really meant to use an operator, but this is highly likely to be
           incorrect.  For example, if you say "*foo *foo" it will be
           interpreted as if you said "*foo * 'foo'".

       Optional parameter lacks default expression
           (F) In a subroutine signature, you wrote something like "$a =",
           making a named optional parameter without a default value.  A
           nameless optional parameter is permitted to have no default value,
           but a named one must have a specific default.  You probably want
           "$a = undef".

       "our" variable %s redeclared
           (W shadow) You seem to have already declared the same global once
           before in the current lexical scope.

       Out of memory!
           (X) The malloc() function returned 0, indicating there was
           insufficient remaining memory (or virtual memory) to satisfy the
           request.  Perl has no option but to exit immediately.

           At least in Unix you may be able to get past this by increasing
           your process datasize limits: in csh/tcsh use "limit" and "limit
           datasize n" (where "n" is the number of kilobytes) to check the
           current limits and change them, and in ksh/bash/zsh use "ulimit -a"
           and "ulimit -d n", respectively.

       Out of memory during %s extend
           (X) An attempt was made to extend an array, a list, or a string
           beyond the largest possible memory allocation.

       Out of memory during "large" request for %s
           (F) The malloc() function returned 0, indicating there was
           insufficient remaining memory (or virtual memory) to satisfy the
           request.  However, the request was judged large enough (compile-
           time default is 64K), so a possibility to shut down by trapping
           this error is granted.

       Out of memory during request for %s
           (X)(F) The malloc() function returned 0, indicating there was
           insufficient remaining memory (or virtual memory) to satisfy the
           request.

           The request was judged to be small, so the possibility to trap it
           depends on the way perl was compiled.  By default it is not
           trappable.  However, if compiled for this, Perl may use the
           contents of $^M as an emergency pool after die()ing with this
           message.  In this case the error is trappable once, and the error
           message will include the line and file where the failed request
           happened.

       Out of memory during ridiculously large request
           (F) You can't allocate more than 2^31+"small amount" bytes.  This
           error is most likely to be caused by a typo in the Perl program.
           e.g., $arr[time] instead of $arr[$time].

       Out of memory for yacc stack
           (F) The yacc parser wanted to grow its stack so it could continue
           parsing, but realloc() wouldn't give it more memory, virtual or
           otherwise.

       '.' outside of string in pack
           (F) The argument to a '.' in your template tried to move the
           working position to before the start of the packed string being
           built.

       '@' outside of string in unpack
           (F) You had a template that specified an absolute position outside
           the string being unpacked.  See "pack" in perlfunc.

       '@' outside of string with malformed UTF-8 in unpack
           (F) You had a template that specified an absolute position outside
           the string being unpacked.  The string being unpacked was also
           invalid UTF-8.  See "pack" in perlfunc.

       overload arg '%s' is invalid
           (W overload) The overload pragma was passed an argument it did not
           recognize.  Did you mistype an operator?

       Overloaded dereference did not return a reference
           (F) An object with an overloaded dereference operator was
           dereferenced, but the overloaded operation did not return a
           reference.  See overload.

       Overloaded qr did not return a REGEXP
           (F) An object with a "qr" overload was used as part of a match, but
           the overloaded operation didn't return a compiled regexp.  See
           overload.

       %s package attribute may clash with future reserved word: %s
           (W reserved) A lowercase attribute name was used that had a
           package-specific handler.  That name might have a meaning to Perl
           itself some day, even though it doesn't yet.  Perhaps you should
           use a mixed-case attribute name, instead.  See attributes.

       pack/unpack repeat count overflow
           (F) You can't specify a repeat count so large that it overflows
           your signed integers.  See "pack" in perlfunc.

       page overflow
           (W io) A single call to write() produced more lines than can fit on
           a page.  See perlform.

       panic: %s
           (P) An internal error.

       panic: attempt to call %s in %s
           (P) One of the file test operators entered a code branch that calls
           an ACL related-function, but that function is not available on this
           platform.  Earlier checks mean that it should not be possible to
           enter this branch on this platform.

       panic: child pseudo-process was never scheduled
           (P) A child pseudo-process in the ithreads implementation on
           Windows was not scheduled within the time period allowed and
           therefore was not able to initialize properly.

       panic: ck_grep, type=%u
           (P) Failed an internal consistency check trying to compile a grep.

       panic: corrupt saved stack index %ld
           (P) The savestack was requested to restore more localized values
           than there are in the savestack.

       panic: del_backref
           (P) Failed an internal consistency check while trying to reset a
           weak reference.

       panic: do_subst
           (P) The internal pp_subst() routine was called with invalid
           operational data.

       panic: do_trans_%s
           (P) The internal do_trans routines were called with invalid
           operational data.

       panic: fold_constants JMPENV_PUSH returned %d
           (P) While attempting folding constants an exception other than an
           "eval" failure was caught.

       panic: frexp: %f
           (P) The library function frexp() failed, making printf("%f")
           impossible.

       panic: goto, type=%u, ix=%ld
           (P) We popped the context stack to a context with the specified
           label, and then discovered it wasn't a context we know how to do a
           goto in.

       panic: gp_free failed to free glob pointer
           (P) The internal routine used to clear a typeglob's entries tried
           repeatedly, but each time something re-created entries in the glob.
           Most likely the glob contains an object with a reference back to
           the glob and a destructor that adds a new object to the glob.

       panic: INTERPCASEMOD, %s
           (P) The lexer got into a bad state at a case modifier.

       panic: INTERPCONCAT, %s
           (P) The lexer got into a bad state parsing a string with brackets.

       panic: kid popen errno read
           (F) A forked child returned an incomprehensible message about its
           errno.

       panic: last, type=%u
           (P) We popped the context stack to a block context, and then
           discovered it wasn't a block context.

       panic: leave_scope clearsv
           (P) A writable lexical variable became read-only somehow within the
           scope.

       panic: leave_scope inconsistency %u
           (P) The savestack probably got out of sync.  At least, there was an
           invalid enum on the top of it.

       panic: magic_killbackrefs
           (P) Failed an internal consistency check while trying to reset all
           weak references to an object.

       panic: malloc, %s
           (P) Something requested a negative number of bytes of malloc.

       panic: memory wrap
           (P) Something tried to allocate either more memory than possible or
           a negative amount.

       panic: pad_alloc, %p!=%p
           (P) The compiler got confused about which scratch pad it was
           allocating and freeing temporaries and lexicals from.

       panic: pad_free curpad, %p!=%p
           (P) The compiler got confused about which scratch pad it was
           allocating and freeing temporaries and lexicals from.

       panic: pad_free po
           (P) A zero scratch pad offset was detected internally.  An attempt
           was made to free a target that had not been allocated to begin
           with.

       panic: pad_reset curpad, %p!=%p
           (P) The compiler got confused about which scratch pad it was
           allocating and freeing temporaries and lexicals from.

       panic: pad_sv po
           (P) A zero scratch pad offset was detected internally.  Most likely
           an operator needed a target but that target had not been allocated
           for whatever reason.

       panic: pad_swipe curpad, %p!=%p
           (P) The compiler got confused about which scratch pad it was
           allocating and freeing temporaries and lexicals from.

       panic: pad_swipe po
           (P) An invalid scratch pad offset was detected internally.

       panic: pp_iter, type=%u
           (P) The foreach iterator got called in a non-loop context frame.

       panic: pp_match%s
           (P) The internal pp_match() routine was called with invalid
           operational data.

       panic: realloc, %s
           (P) Something requested a negative number of bytes of realloc.

       panic: reference miscount on nsv in sv_replace() (%d != 1)
           (P) The internal sv_replace() function was handed a new SV with a
           reference count other than 1.

       panic: restartop in %s
           (P) Some internal routine requested a goto (or something like it),
           and didn't supply the destination.

       panic: return, type=%u
           (P) We popped the context stack to a subroutine or eval context,
           and then discovered it wasn't a subroutine or eval context.

       panic: scan_num, %s
           (P) scan_num() got called on something that wasn't a number.

       panic: Sequence (?{...}): no code block found in regex m/%s/
           (P) While compiling a pattern that has embedded (?{}) or (??{})
           code blocks, perl couldn't locate the code block that should have
           already been seen and compiled by perl before control passed to the
           regex compiler.

       panic: strxfrm() gets absurd - a => %u, ab => %u
           (P) The interpreter's sanity check of the C function strxfrm()
           failed.  In your current locale the returned transformation of the
           string "ab" is shorter than that of the string "a", which makes no
           sense.

       panic: sv_chop %s
           (P) The sv_chop() routine was passed a position that is not within
           the scalar's string buffer.

       panic: sv_insert, midend=%p, bigend=%p
           (P) The sv_insert() routine was told to remove more string than
           there was string.

       panic: top_env
           (P) The compiler attempted to do a goto, or something weird like
           that.

       panic: unimplemented op %s (#%d) called
           (P) The compiler is screwed up and attempted to use an op that
           isn't permitted at run time.

       panic: unknown OA_*: %x
           (P) The internal routine that handles arguments to "&CORE::foo()"
           subroutine calls was unable to determine what type of arguments
           were expected.

       panic: utf16_to_utf8: odd bytelen
           (P) Something tried to call utf16_to_utf8 with an odd (as opposed
           to even) byte length.

       panic: utf16_to_utf8_reversed: odd bytelen
           (P) Something tried to call utf16_to_utf8_reversed with an odd (as
           opposed to even) byte length.

       panic: yylex, %s
           (P) The lexer got into a bad state while processing a case
           modifier.

       Parentheses missing around "%s" list
           (W parenthesis) You said something like

               my $foo, $bar = @_;

           when you meant

               my ($foo, $bar) = @_;

           Remember that "my", "our", "local" and "state" bind tighter than
           comma.

       Parsing code internal error (%s)
           (F) Parsing code supplied by an extension violated the parser's API
           in a detectable way.

       Pattern subroutine nesting without pos change exceeded limit in regex
           (F) You used a pattern that uses too many nested subpattern calls
           without consuming any text.  Restructure the pattern so text is
           consumed before the nesting limit is exceeded.

       "-p" destination: %s
           (F) An error occurred during the implicit output invoked by the
           "-p" command-line switch.  (This output goes to STDOUT unless
           you've redirected it with select().)

       Perl API version %s of %s does not match %s
           (F) The XS module in question was compiled against a different
           incompatible version of Perl than the one that has loaded the XS
           module.

       Perl folding rules are not up-to-date for 0x%X; please use the perlbug
       utility to report; in regex; marked by <-- HERE in m/%s/
           (S regexp) You used a regular expression with case-insensitive
           matching, and there is a bug in Perl in which the built-in regular
           expression folding rules are not accurate.  This may lead to
           incorrect results.  Please report this as a bug to
           <https://github.com/Perl/perl5/issues>.

       PerlIO layer ':win32' is experimental
           (S experimental::win32_perlio) The ":win32" PerlIO layer is
           experimental.  If you want to take the risk of using this layer,
           simply disable this warning:

               no warnings "experimental::win32_perlio";

       Perl_my_%s() not available
           (F) Your platform has very uncommon byte-order and integer size, so
           it was not possible to set up some or all fixed-width byte-order
           conversion functions.  This is only a problem when you're using the
           '<' or '>' modifiers in (un)pack templates.  See "pack" in
           perlfunc.

       Perl %s required (did you mean %s?)--this is only %s, stopped
           (F) The code you are trying to run has asked for a newer version of
           Perl than you are running.  Perhaps "use 5.10" was written instead
           of "use 5.010" or "use v5.10".  Without the leading "v", the number
           is interpreted as a decimal, with every three digits after the
           decimal point representing a part of the version number.  So 5.10
           is equivalent to v5.100.

       Perl %s required--this is only %s, stopped
           (F) The module in question uses features of a version of Perl more
           recent than the currently running version.  How long has it been
           since you upgraded, anyway?  See "require" in perlfunc.

       PERL_SH_DIR too long
           (F) An error peculiar to OS/2.  PERL_SH_DIR is the directory to
           find the "sh"-shell in.  See "PERL_SH_DIR" in perlos2.

       PERL_SIGNALS illegal: "%s"
           (X) See "PERL_SIGNALS" in perlrun for legal values.

       Perls since %s too modern--this is %s, stopped
           (F) The code you are trying to run claims it will not run on the
           version of Perl you are using because it is too new.  Maybe the
           code needs to be updated, or maybe it is simply wrong and the
           version check should just be removed.

       perl: warning: Non hex character in '$ENV{PERL_HASH_SEED}', seed only
       partially set
           (S) PERL_HASH_SEED should match /^\s*(?:0x)?[0-9a-fA-F]+\s*\z/ but
           it contained a non hex character.  This could mean you are not
           using the hash seed you think you are.

       perl: warning: Setting locale failed.
           (S) The whole warning message will look something like:

                   perl: warning: Setting locale failed.
                   perl: warning: Please check that your locale settings:
                           LC_ALL = "En_US",
                           LANG = (unset)
                       are supported and installed on your system.
                   perl: warning: Falling back to the standard locale ("C").

           Exactly what were the failed locale settings varies.  In the above
           the settings were that the LC_ALL was "En_US" and the LANG had no
           value.  This error means that Perl detected that you and/or your
           operating system supplier and/or system administrator have set up
           the so-called locale system but Perl could not use those settings.
           This was not dead serious, fortunately: there is a "default locale"
           called "C" that Perl can and will use, and the script will be run.
           Before you really fix the problem, however, you will get the same
           error message each time you run Perl.  How to really fix the
           problem can be found in perllocale section LOCALE PROBLEMS.

       perl: warning: strange setting in '$ENV{PERL_PERTURB_KEYS}': '%s'
           (S) Perl was run with the environment variable PERL_PERTURB_KEYS
           defined but containing an unexpected value.  The legal values of
           this setting are as follows.

             Numeric | String        | Result
             --------+---------------+-----------------------------------------
             0       | NO            | Disables key traversal randomization
             1       | RANDOM        | Enables full key traversal randomization
             2       | DETERMINISTIC | Enables repeatable key traversal
                     |               | randomization

           Both numeric and string values are accepted, but note that string
           values are case sensitive.  The default for this setting is
           "RANDOM" or 1.

       pid %x not a child
           (W exec) A warning peculiar to VMS.  Waitpid() was asked to wait
           for a process which isn't a subprocess of the current process.
           While this is fine from VMS' perspective, it's probably not what
           you intended.

       'P' must have an explicit size in unpack
           (F) The unpack format P must have an explicit size, not "*".

       POSIX class [:%s:] unknown in regex; marked by <-- HERE in m/%s/
           (F) The class in the character class [: :] syntax is unknown.  The
           <-- HERE shows whereabouts in the regular expression the problem
           was discovered.  Note that the POSIX character classes do not have
           the "is" prefix the corresponding C interfaces have: in other
           words, it's "[[:print:]]", not "isprint".  See perlre.

       POSIX getpgrp can't take an argument
           (F) Your system has POSIX getpgrp(), which takes no argument,
           unlike the BSD version, which takes a pid.

       POSIX syntax [%c %c] belongs inside character classes%s in regex;
       marked by <-- HERE in m/%s/
           (W regexp) Perl thinks that you intended to write a POSIX character
           class, but didn't use enough brackets.  These POSIX class
           constructs [: :], [= =], and [. .]  go inside character classes,
           the [] are part of the construct, for example:
           "qr/[012[:alpha:]345]/".  What the regular expression pattern
           compiled to is probably not what you were intending.  For example,
           "qr/[:alpha:]/" compiles to a regular bracketed character class
           consisting of the four characters ":",  "a",  "l", "h", and "p".
           To specify the POSIX class, it should have been written
           "qr/[[:alpha:]]/".

           Note that [= =] and [. .] are not currently implemented; they are
           simply placeholders for future extensions and will cause fatal
           errors.  The <-- HERE shows whereabouts in the regular expression
           the problem was discovered.  See perlre.

           If the specification of the class was not completely valid, the
           message indicates that.

       POSIX syntax [. .] is reserved for future extensions in regex; marked
       by <-- HERE in m/%s/
           (F) Within regular expression character classes ([]) the syntax
           beginning with "[." and ending with ".]" is reserved for future
           extensions.  If you need to represent those character sequences
           inside a regular expression character class, just quote the square
           brackets with the backslash: "\[."  and ".\]".  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.
           See perlre.

       POSIX syntax [= =] is reserved for future extensions in regex; marked
       by <-- HERE in m/%s/
           (F) Within regular expression character classes ([]) the syntax
           beginning with "[=" and ending with "=]" is reserved for future
           extensions.  If you need to represent those character sequences
           inside a regular expression character class, just quote the square
           brackets with the backslash: "\[=" and "=\]".  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.
           See perlre.

       Possible attempt to put comments in qw() list
           (W qw) qw() lists contain items separated by whitespace; as with
           literal strings, comment characters are not ignored, but are
           instead treated as literal data.  (You may have used different
           delimiters than the parentheses shown here; braces are also
           frequently used.)

           You probably wrote something like this:

               @list = qw(
                   a # a comment
                   b # another comment
               );

           when you should have written this:

               @list = qw(
                   a
                   b
               );

           If you really want comments, build your list the old-fashioned way,
           with quotes and commas:

               @list = (
                   'a',    # a comment
                   'b',    # another comment
               );

       Possible attempt to separate words with commas
           (W qw) qw() lists contain items separated by whitespace; therefore
           commas aren't needed to separate the items.  (You may have used
           different delimiters than the parentheses shown here; braces are
           also frequently used.)

           You probably wrote something like this:

               qw! a, b, c !;

           which puts literal commas into some of the list items.  Write it
           without commas if you don't want them to appear in your data:

               qw! a b c !;

       Possible memory corruption: %s overflowed 3rd argument
           (F) An ioctl() or fcntl() returned more than Perl was bargaining
           for.  Perl guesses a reasonable buffer size, but puts a sentinel
           byte at the end of the buffer just in case.  This sentinel byte got
           clobbered, and Perl assumes that memory is now corrupted.  See
           "ioctl" in perlfunc.

       Possible precedence issue with control flow operator
           (W syntax) There is a possible problem with the mixing of a control
           flow operator (e.g. "return") and a low-precedence operator like
           "or".  Consider:

               sub { return $a or $b; }

           This is parsed as:

               sub { (return $a) or $b; }

           Which is effectively just:

               sub { return $a; }

           Either use parentheses or the high-precedence variant of the
           operator.

           Note this may be also triggered for constructs like:

               sub { 1 if die; }

       Possible precedence problem on bitwise %s operator
           (W precedence) Your program uses a bitwise logical operator in
           conjunction with a numeric comparison operator, like this :

               if ($x & $y == 0) { ... }

           This expression is actually equivalent to "$x & ($y == 0)", due to
           the higher precedence of "==".  This is probably not what you want.
           (If you really meant to write this, disable the warning, or,
           better, put the parentheses explicitly and write "$x & ($y == 0)").

       Possible unintended interpolation of $\ in regex
           (W ambiguous) You said something like "m/$\/" in a regex.  The
           regex "m/foo$\s+bar/m" translates to: match the word 'foo', the
           output record separator (see "$\" in perlvar) and the letter 's'
           (one time or more) followed by the word 'bar'.

           If this is what you intended then you can silence the warning by
           using "m/${\}/" (for example: "m/foo${\}s+bar/").

           If instead you intended to match the word 'foo' at the end of the
           line followed by whitespace and the word 'bar' on the next line
           then you can use "m/$(?)\/" (for example: "m/foo$(?)\s+bar/").

       Possible unintended interpolation of %s in string
           (W ambiguous) You said something like '@foo' in a double-quoted
           string but there was no array @foo in scope at the time.  If you
           wanted a literal @foo, then write it as \@foo; otherwise find out
           what happened to the array you apparently lost track of.

       Precedence problem: open %s should be open(%s)
           (S precedence) The old irregular construct

               open FOO || die;

           is now misinterpreted as

               open(FOO || die);

           because of the strict regularization of Perl 5's grammar into unary
           and list operators.  (The old open was a little of both.)  You must
           put parentheses around the filehandle, or use the new "or" operator
           instead of "||".

       Premature end of script headers
           See "500 Server error".

       printf() on closed filehandle %s
           (W closed) The filehandle you're writing to got itself closed
           sometime before now.  Check your control flow.

       print() on closed filehandle %s
           (W closed) The filehandle you're printing on got itself closed
           sometime before now.  Check your control flow.

       Process terminated by SIG%s
           (W) This is a standard message issued by OS/2 applications, while
           *nix applications die in silence.  It is considered a feature of
           the OS/2 port.  One can easily disable this by appropriate
           sighandlers, see "Signals" in perlipc.  See also "Process
           terminated by SIGTERM/SIGINT" in perlos2.

       Prototype after '%c' for %s : %s
           (W illegalproto) A character follows % or @ in a prototype.  This
           is useless, since % and @ gobble the rest of the subroutine
           arguments.

       Prototype mismatch: %s vs %s
           (S prototype) The subroutine being declared or defined had
           previously been declared or defined with a different function
           prototype.

       Prototype not terminated
           (F) You've omitted the closing parenthesis in a function prototype
           definition.

       Prototype '%s' overridden by attribute 'prototype(%s)' in %s
           (W prototype) A prototype was declared in both the parentheses
           after the sub name and via the prototype attribute.  The prototype
           in parentheses is useless, since it will be replaced by the
           prototype from the attribute before it's ever used.

       Quantifier follows nothing in regex; marked by <-- HERE in m/%s/
           (F) You started a regular expression with a quantifier.  Backslash
           it if you meant it literally.  The <-- HERE shows whereabouts in
           the regular expression the problem was discovered.  See perlre.

       Quantifier in {,} bigger than %d in regex; marked by <-- HERE in m/%s/
           (F) There is currently a limit to the size of the min and max
           values of the {min,max} construct.  The <-- HERE shows whereabouts
           in the regular expression the problem was discovered.  See perlre.

       Quantifier {n,m} with n > m can't match in regex
       Quantifier {n,m} with n > m can't match in regex; marked by <-- HERE in
       m/%s/
           (W regexp) Minima should be less than or equal to maxima.  If you
           really want your regexp to match something 0 times, just put {0}.

       Quantifier unexpected on zero-length expression in regex m/%s/
           (W regexp) You applied a regular expression quantifier in a place
           where it makes no sense, such as on a zero-width assertion.  Try
           putting the quantifier inside the assertion instead.  For example,
           the way to match "abc" provided that it is followed by three
           repetitions of "xyz" is "/abc(?=(?:xyz){3})/", not
           "/abc(?=xyz){3}/".

       Range iterator outside integer range
           (F) One (or both) of the numeric arguments to the range operator
           ".."  are outside the range which can be represented by integers
           internally.  One possible workaround is to force Perl to use
           magical string increment by prepending "0" to your numbers.

       Ranges of ASCII printables should be some subset of "0-9", "A-Z", or
       "a-z" in regex; marked by <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'" or within "(?[...])")

           Stricter rules help to find typos and other errors.  Perhaps you
           didn't even intend a range here, if the "-" was meant to be some
           other character, or should have been escaped (like "\-").  If you
           did intend a range, the one that was used is not portable between
           ASCII and EBCDIC platforms, and doesn't have an obvious meaning to
           a casual reader.

            [3-7]    # OK; Obvious and portable
            [d-g]    # OK; Obvious and portable
            [A-Y]    # OK; Obvious and portable
            [A-z]    # WRONG; Not portable; not clear what is meant
            [a-Z]    # WRONG; Not portable; not clear what is meant
            [%-.]    # WRONG; Not portable; not clear what is meant
            [\x41-Z] # WRONG; Not portable; not obvious to non-geek

           (You can force portability by specifying a Unicode range, which
           means that the endpoints are specified by "\N{...}", but the
           meaning may still not be obvious.)  The stricter rules require that
           ranges that start or stop with an ASCII character that is not a
           control have all their endpoints be the literal character, and not
           some escape sequence (like "\x41"), and the ranges must be all
           digits, or all uppercase letters, or all lowercase letters.

       Ranges of digits should be from the same group in regex; marked by
       <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'" or within "(?[...])")

           Stricter rules help to find typos and other errors.  You included a
           range, and at least one of the end points is a decimal digit.
           Under the stricter rules, when this happens, both end points should
           be digits in the same group of 10 consecutive digits.

       readdir() attempted on invalid dirhandle %s
           (W io) The dirhandle you're reading from is either closed or not
           really a dirhandle.  Check your control flow.

       readline() on closed filehandle %s
           (W closed) The filehandle you're reading from got itself closed
           sometime before now.  Check your control flow.

       readline() on unopened filehandle %s
           (W unopened) The filehandle you're reading from was never opened.
           Check your control flow.

       read() on closed filehandle %s
           (W closed) You tried to read from a closed filehandle.

       read() on unopened filehandle %s
           (W unopened) You tried to read from a filehandle that was never
           opened.

       Reallocation too large: %x
           (F) You can't allocate more than 64K on an MS-DOS machine.

       realloc() of freed memory ignored
           (S malloc) An internal routine called realloc() on something that
           had already been freed.

       Recompile perl with -DDEBUGGING to use -D switch
           (S debugging) You can't use the -D option unless the code to
           produce the desired output is compiled into Perl, which entails
           some overhead, which is why it's currently left out of your copy.

       Recursive call to Perl_load_module in PerlIO_find_layer
           (P) It is currently not permitted to load modules when creating a
           filehandle inside an %INC hook.  This can happen with "open my $fh,
           '<', \$scalar", which implicitly loads PerlIO::scalar.  Try loading
           PerlIO::scalar explicitly first.

       Recursive inheritance detected in package '%s'
           (F) While calculating the method resolution order (MRO) of a
           package, Perl believes it found an infinite loop in the @ISA
           hierarchy.  This is a crude check that bails out after 100 levels
           of @ISA depth.

       Redundant argument in %s
           (W redundant) You called a function with more arguments than other
           arguments you supplied indicated would be needed.  Currently only
           emitted when a printf-type format required fewer arguments than
           were supplied, but might be used in the future for e.g. "pack" in
           perlfunc.

       refcnt_dec: fd %d%s
       refcnt: fd %d%s
       refcnt_inc: fd %d%s
           (P) Perl's I/O implementation failed an internal consistency check.
           If you see this message, something is very wrong.

       Reference found where even-sized list expected
           (W misc) You gave a single reference where Perl was expecting a
           list with an even number of elements (for assignment to a hash).
           This usually means that you used the anon hash constructor when you
           meant to use parens.  In any case, a hash requires key/value pairs.

               %hash = { one => 1, two => 2, };    # WRONG
               %hash = [ qw/ an anon array / ];    # WRONG
               %hash = ( one => 1, two => 2, );    # right
               %hash = qw( one 1 two 2 );                  # also fine

       Reference is already weak
           (W misc) You have attempted to weaken a reference that is already
           weak.  Doing so has no effect.

       Reference is not weak
           (W misc) You have attempted to unweaken a reference that is not
           weak.  Doing so has no effect.

       Reference to invalid group 0 in regex; marked by <-- HERE in m/%s/
           (F) You used "\g0" or similar in a regular expression.  You may
           refer to capturing parentheses only with strictly positive integers
           (normal backreferences) or with strictly negative integers
           (relative backreferences).  Using 0 does not make sense.

       Reference to nonexistent group in regex; marked by <-- HERE in m/%s/
           (F) You used something like "\7" in your regular expression, but
           there are not at least seven sets of capturing parentheses in the
           expression.  If you wanted to have the character with ordinal 7
           inserted into the regular expression, prepend zeroes to make it
           three digits long: "\007"

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       Reference to nonexistent named group in regex; marked by <-- HERE in
       m/%s/
           (F) You used something like "\k'NAME'" or "\k<NAME>" in your
           regular expression, but there is no corresponding named capturing
           parentheses such as "(?'NAME'...)" or "(?<NAME>...)".  Check if the
           name has been spelled correctly both in the backreference and the
           declaration.

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       Reference to nonexistent or unclosed group in regex; marked by <-- HERE
       in m/%s/
           (F) You used something like "\g{-7}" in your regular expression,
           but there are not at least seven sets of closed capturing
           parentheses in the expression before where the "\g{-7}" was
           located.

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.

       regexp memory corruption
           (P) The regular expression engine got confused by what the regular
           expression compiler gave it.

       Regexp modifier "/%c" may appear a maximum of twice
       Regexp modifier "%c" may appear a maximum of twice in regex; marked by
       <-- HERE in m/%s/
           (F) The regular expression pattern had too many occurrences of the
           specified modifier.  Remove the extraneous ones.

       Regexp modifier "%c" may not appear after the "-" in regex; marked by
       <-- HERE in m/%s/
           (F) Turning off the given modifier has the side effect of turning
           on another one.  Perl currently doesn't allow this.  Reword the
           regular expression to use the modifier you want to turn on (and
           place it before the minus), instead of the one you want to turn
           off.

       Regexp modifier "/%c" may not appear twice
       Regexp modifier "%c" may not appear twice in regex; marked by <-- HERE
       in m/%s/
           (F) The regular expression pattern had too many occurrences of the
           specified modifier.  Remove the extraneous ones.

       Regexp modifiers "/%c" and "/%c" are mutually exclusive
       Regexp modifiers "%c" and "%c" are mutually exclusive in regex; marked
       by <-- HERE in m/%s/
           (F) The regular expression pattern had more than one of these
           mutually exclusive modifiers.  Retain only the modifier that is
           supposed to be there.

       Regexp out of space in regex m/%s/
           (P) A "can't happen" error, because safemalloc() should have caught
           it earlier.

       Repeated format line will never terminate (~~ and @#)
           (F) Your format contains the ~~ repeat-until-blank sequence and a
           numeric field that will never go blank so that the repetition never
           terminates.  You might use ^# instead.  See perlform.

       Replacement list is longer than search list
           (W misc) You have used a replacement list that is longer than the
           search list.  So the additional elements in the replacement list
           are meaningless.

       '(*%s' requires a terminating ':' in regex; marked by <-- HERE in m/%s/
           (F) You used a construct that needs a colon and pattern argument.
           Supply these or check that you are using the right construct.

       '%s' resolved to '\o{%s}%d'
           As of Perl 5.32, this message is no longer generated.  Instead, see
           "Non-octal character '%c' terminates \o early.  Resolved as "%s"".
           (W misc, regexp)  You wrote something like "\08", or "\179" in a
           double-quotish string.  All but the last digit is treated as a
           single character, specified in octal.  The last digit is the next
           character in the string.  To tell Perl that this is indeed what you
           want, you can use the "\o{ }" syntax, or use exactly three digits
           to specify the octal for the character.

       Reversed %s= operator
           (W syntax) You wrote your assignment operator backwards.  The =
           must always come last, to avoid ambiguity with subsequent unary
           operators.

       rewinddir() attempted on invalid dirhandle %s
           (W io) The dirhandle you tried to do a rewinddir() on is either
           closed or not really a dirhandle.  Check your control flow.

       Scalars leaked: %d
           (S internal) Something went wrong in Perl's internal bookkeeping of
           scalars: not all scalar variables were deallocated by the time Perl
           exited.  What this usually indicates is a memory leak, which is of
           course bad, especially if the Perl program is intended to be long-
           running.

       Scalar value @%s[%s] better written as $%s[%s]
           (W syntax) You've used an array slice (indicated by @) to select a
           single element of an array.  Generally it's better to ask for a
           scalar value (indicated by $).  The difference is that $foo[&bar]
           always behaves like a scalar, both when assigning to it and when
           evaluating its argument, while @foo[&bar] behaves like a list when
           you assign to it, and provides a list context to its subscript,
           which can do weird things if you're expecting only one subscript.

           On the other hand, if you were actually hoping to treat the array
           element as a list, you need to look into how references work,
           because Perl will not magically convert between scalars and lists
           for you.  See perlref.

       Scalar value @%s{%s} better written as $%s{%s}
           (W syntax) You've used a hash slice (indicated by @) to select a
           single element of a hash.  Generally it's better to ask for a
           scalar value (indicated by $).  The difference is that $foo{&bar}
           always behaves like a scalar, both when assigning to it and when
           evaluating its argument, while @foo{&bar} behaves like a list when
           you assign to it, and provides a list context to its subscript,
           which can do weird things if you're expecting only one subscript.

           On the other hand, if you were actually hoping to treat the hash
           element as a list, you need to look into how references work,
           because Perl will not magically convert between scalars and lists
           for you.  See perlref.

       Search pattern not terminated
           (F) The lexer couldn't find the final delimiter of a // or m{}
           construct.  Remember that bracketing delimiters count nesting
           level.  Missing the leading "$" from a variable $m may cause this
           error.

           Note that since Perl 5.10.0 a // can also be the defined-or
           construct, not just the empty search pattern.  Therefore code
           written in Perl 5.10.0 or later that uses the // as the defined-or
           can be misparsed by pre-5.10.0 Perls as a non-terminated search
           pattern.

       seekdir() attempted on invalid dirhandle %s
           (W io) The dirhandle you are doing a seekdir() on is either closed
           or not really a dirhandle.  Check your control flow.

       %sseek() on unopened filehandle
           (W unopened) You tried to use the seek() or sysseek() function on a
           filehandle that was either never opened or has since been closed.

       select not implemented
           (F) This machine doesn't implement the select() system call.

       Self-ties of arrays and hashes are not supported
           (F) Self-ties are of arrays and hashes are not supported in the
           current implementation.

       Semicolon seems to be missing
           (W semicolon) A nearby syntax error was probably caused by a
           missing semicolon, or possibly some other missing operator, such as
           a comma.

       semi-panic: attempt to dup freed string
           (S internal) The internal newSVsv() routine was called to duplicate
           a scalar that had previously been marked as free.

       sem%s not implemented
           (F) You don't have System V semaphore IPC on your system.

       send() on closed socket %s
           (W closed) The socket you're sending to got itself closed sometime
           before now.  Check your control flow.

       Sequence "\c{" invalid
           (F) These three characters may not appear in sequence in a double-
           quotish context.  This message is raised only on non-ASCII
           platforms (a different error message is output on ASCII ones).  If
           you were intending to specify a control character with this
           sequence, you'll have to use a different way to specify it.

       Sequence (? incomplete in regex; marked by <-- HERE in m/%s/
           (F) A regular expression ended with an incomplete extension (?.
           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Sequence (?%c...) not implemented in regex; marked by <-- HERE in m/%s/
           (F) A proposed regular expression extension has the character
           reserved but has not yet been written.  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.
           See perlre.

       Sequence (?%s...) not recognized in regex; marked by <-- HERE in m/%s/
           (F) You used a regular expression extension that doesn't make
           sense.  The <-- HERE shows whereabouts in the regular expression
           the problem was discovered.  This may happen when using the
           "(?^...)" construct to tell Perl to use the default regular
           expression modifiers, and you redundantly specify a default
           modifier.  For other causes, see perlre.

       Sequence (?#... not terminated in regex m/%s/
           (F) A regular expression comment must be terminated by a closing
           parenthesis.  Embedded parentheses aren't allowed.  See perlre.

       Sequence (?&... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named reference of the form "(?&...)" was missing the final
           closing parenthesis after the name.  The <-- HERE shows whereabouts
           in the regular expression the problem was discovered.

       Sequence (?%c... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named group of the form "(?'...')" or "(?<...>)" was missing
           the final closing quote or angle bracket.  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.

       Sequence (?(%c... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named reference of the form "(?('...')...)" or
           "(?(<...>)...)" was missing the final closing quote or angle
           bracket after the name.  The <-- HERE shows whereabouts in the
           regular expression the problem was discovered.

       Sequence (?... not terminated in regex; marked by <-- HERE in m/%s/
           (F) There was no matching closing parenthesis for the '('.  The
           <-- HERE shows whereabouts in the regular expression the problem
           was discovered.

       Sequence \%s... not terminated in regex; marked by <-- HERE in m/%s/
           (F) The regular expression expects a mandatory argument following
           the escape sequence and this has been omitted or incorrectly
           written.

       Sequence (?{...}) not terminated with ')'
           (F) The end of the perl code contained within the {...} must be
           followed immediately by a ')'.

       Sequence (?P>... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named reference of the form "(?P>...)" was missing the final
           closing parenthesis after the name.  The <-- HERE shows whereabouts
           in the regular expression the problem was discovered.

       Sequence (?P<... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named group of the form "(?P<...>')" was missing the final
           closing angle bracket.  The <-- HERE shows whereabouts in the
           regular expression the problem was discovered.

       Sequence ?P=... not terminated in regex; marked by <-- HERE in m/%s/
           (F) A named reference of the form "(?P=...)" was missing the final
           closing parenthesis after the name.  The <-- HERE shows whereabouts
           in the regular expression the problem was discovered.

       Sequence (?R) not terminated in regex m/%s/
           (F) An "(?R)" or "(?0)" sequence in a regular expression was
           missing the final parenthesis.

       500 Server error
           (A) This is the error message generally seen in a browser window
           when trying to run a CGI program (including SSI) over the web.  The
           actual error text varies widely from server to server.  The most
           frequently-seen variants are "500 Server error", "Method
           (something) not permitted", "Document contains no data", "Premature
           end of script headers", and "Did not produce a valid header".

           This is a CGI error, not a Perl error.

           You need to make sure your script is executable, is accessible by
           the user CGI is running the script under (which is probably not the
           user account you tested it under), does not rely on any environment
           variables (like PATH) from the user it isn't running under, and
           isn't in a location where the CGI server can't find it, basically,
           more or less.  Please see the following for more information:

                   https://www.perl.org/CGI_MetaFAQ.html
                   http://www.htmlhelp.org/faq/cgifaq.html
                   http://www.w3.org/Security/Faq/

           You should also look at perlfaq9.

       setegid() not implemented
           (F) You tried to assign to $), and your operating system doesn't
           support the setegid() system call (or equivalent), or at least
           Configure didn't think so.

       seteuid() not implemented
           (F) You tried to assign to $>, and your operating system doesn't
           support the seteuid() system call (or equivalent), or at least
           Configure didn't think so.

       setpgrp can't take arguments
           (F) Your system has the setpgrp() from BSD 4.2, which takes no
           arguments, unlike POSIX setpgid(), which takes a process ID and
           process group ID.

       setrgid() not implemented
           (F) You tried to assign to $(, and your operating system doesn't
           support the setrgid() system call (or equivalent), or at least
           Configure didn't think so.

       setruid() not implemented
           (F) You tried to assign to $<, and your operating system doesn't
           support the setruid() system call (or equivalent), or at least
           Configure didn't think so.

       setsockopt() on closed socket %s
           (W closed) You tried to set a socket option on a closed socket.
           Did you forget to check the return value of your socket() call?
           See "setsockopt" in perlfunc.

       Setting $/ to a reference to %s is forbidden
           (F) You assigned a reference to a scalar to $/ where the referenced
           item is not a positive integer.  In older perls this appeared to
           work the same as setting it to "undef" but was in fact internally
           different, less efficient and with very bad luck could have
           resulted in your file being split by a stringified form of the
           reference.

           In Perl 5.20.0 this was changed so that it would be exactly the
           same as setting $/ to undef, with the exception that this warning
           would be thrown.

           You are recommended to change your code to set $/ to "undef"
           explicitly if you wish to slurp the file.  As of Perl 5.28
           assigning $/ to a reference to an integer which isn't positive is a
           fatal error.

       Setting $/ to %s reference is forbidden
           (F) You tried to assign a reference to a non integer to $/.  In
           older Perls this would have behaved similarly to setting it to a
           reference to a positive integer, where the integer was the address
           of the reference.  As of Perl 5.20.0 this is a fatal error, to
           allow future versions of Perl to use non-integer refs for more
           interesting purposes.

       shm%s not implemented
           (F) You don't have System V shared memory IPC on your system.

       !=~ should be !~
           (W syntax) The non-matching operator is !~, not !=~.  !=~ will be
           interpreted as the != (numeric not equal) and ~ (1's complement)
           operators: probably not what you intended.

       /%s/ should probably be written as "%s"
           (W syntax) You have used a pattern where Perl expected to find a
           string, as in the first argument to "join".  Perl will treat the
           true or false result of matching the pattern against $_ as the
           string, which is probably not what you had in mind.

       shutdown() on closed socket %s
           (W closed) You tried to do a shutdown on a closed socket.  Seems a
           bit superfluous.

       SIG%s handler "%s" not defined
           (W signal) The signal handler named in %SIG doesn't, in fact,
           exist.  Perhaps you put it into the wrong package?

       Slab leaked from cv %p
           (S) If you see this message, then something is seriously wrong with
           the internal bookkeeping of op trees.  An op tree needed to be
           freed after a compilation error, but could not be found, so it was
           leaked instead.

       sleep(%u) too large
           (W overflow) You called "sleep" with a number that was larger than
           it can reliably handle and "sleep" probably slept for less time
           than requested.

       Slurpy parameter not last
           (F) In a subroutine signature, you put something after a slurpy
           (array or hash) parameter.  The slurpy parameter takes all the
           available arguments, so there can't be any left to fill later
           parameters.

       Smart matching a non-overloaded object breaks encapsulation
           (F) You should not use the "~~" operator on an object that does not
           overload it: Perl refuses to use the object's underlying structure
           for the smart match.

       Smartmatch is experimental
           (S experimental::smartmatch) This warning is emitted if you use the
           smartmatch ("~~") operator.  This is currently an experimental
           feature, and its details are subject to change in future releases
           of Perl.  Particularly, its current behavior is noticed for being
           unnecessarily complex and unintuitive, and is very likely to be
           overhauled.

       Sorry, hash keys must be smaller than 2**31 bytes
           (F) You tried to create a hash containing a very large key, where
           "very large" means that it needs at least 2 gigabytes to store.
           Unfortunately, Perl doesn't yet handle such large hash keys. You
           should reconsider your design to avoid hashing such a long string
           directly.

       sort is now a reserved word
           (F) An ancient error message that almost nobody ever runs into
           anymore.  But before sort was a keyword, people sometimes used it
           as a filehandle.

       Source filters apply only to byte streams
           (F) You tried to activate a source filter (usually by loading a
           source filter module) within a string passed to "eval".  This is
           not permitted under the "unicode_eval" feature.  Consider using
           "evalbytes" instead.  See feature.

       splice() offset past end of array
           (W misc) You attempted to specify an offset that was past the end
           of the array passed to splice().  Splicing will instead commence at
           the end of the array, rather than past it.  If this isn't what you
           want, try explicitly pre-extending the array by assigning $#array =
           $offset.  See "splice" in perlfunc.

       Split loop
           (P) The split was looping infinitely.  (Obviously, a split
           shouldn't iterate more times than there are characters of input,
           which is what happened.)  See "split" in perlfunc.

       Statement unlikely to be reached
           (W exec) You did an exec() with some statement after it other than
           a die().  This is almost always an error, because exec() never
           returns unless there was a failure.  You probably wanted to use
           system() instead, which does return.  To suppress this warning, put
           the exec() in a block by itself.

       "state" subroutine %s can't be in a package
           (F) Lexically scoped subroutines aren't in a package, so it doesn't
           make sense to try to declare one with a package qualifier on the
           front.

       "state %s" used in sort comparison
           (W syntax) The package variables $a and $b are used for sort
           comparisons.  You used $a or $b in as an operand to the "<=>" or
           "cmp" operator inside a sort comparison block, and the variable had
           earlier been declared as a lexical variable.  Either qualify the
           sort variable with the package name, or rename the lexical
           variable.

       "state" variable %s can't be in a package
           (F) Lexically scoped variables aren't in a package, so it doesn't
           make sense to try to declare one with a package qualifier on the
           front.  Use local() if you want to localize a package variable.

       stat() on unopened filehandle %s
           (W unopened) You tried to use the stat() function on a filehandle
           that was either never opened or has since been closed.

       Strings with code points over 0xFF may not be mapped into in-memory
       file handles
           (W utf8) You tried to open a reference to a scalar for read or
           append where the scalar contained code points over 0xFF.  In-memory
           files model on-disk files and can only contain bytes.

       Stub found while resolving method "%s" overloading "%s" in package "%s"
           (P) Overloading resolution over @ISA tree may be broken by
           importation stubs.  Stubs should never be implicitly created, but
           explicit calls to "can" may break this.

       Subroutine attributes must come before the signature
           (F) When subroutine signatures are enabled, any subroutine
           attributes must come before the signature. Note that this order was
           the opposite in versions 5.22..5.26. So:

               sub foo :lvalue ($a, $b) { ... }  # 5.20 and 5.28 +
               sub foo ($a, $b) :lvalue { ... }  # 5.22 .. 5.26

       Subroutine "&%s" is not available
           (W closure) During compilation, an inner named subroutine or eval
           is attempting to capture an outer lexical subroutine that is not
           currently available.  This can happen for one of two reasons.
           First, the lexical subroutine may be declared in an outer anonymous
           subroutine that has not yet been created.  (Remember that named
           subs are created at compile time, while anonymous subs are created
           at run-time.)  For example,

               sub { my sub a {...} sub f { \&a } }

           At the time that f is created, it can't capture the current "a"
           sub, since the anonymous subroutine hasn't been created yet.
           Conversely, the following won't give a warning since the anonymous
           subroutine has by now been created and is live:

               sub { my sub a {...} eval 'sub f { \&a }' }->();

           The second situation is caused by an eval accessing a lexical
           subroutine that has gone out of scope, for example,

               sub f {
                   my sub a {...}
                   sub { eval '\&a' }
               }
               f()->();

           Here, when the '\&a' in the eval is being compiled, f() is not
           currently being executed, so its &a is not available for capture.

       "%s" subroutine &%s masks earlier declaration in same %s
           (W shadow) A "my" or "state" subroutine has been redeclared in the
           current scope or statement, effectively eliminating all access to
           the previous instance.  This is almost always a typographical
           error.  Note that the earlier subroutine will still exist until the
           end of the scope or until all closure references to it are
           destroyed.

       Subroutine %s redefined
           (W redefine) You redefined a subroutine.  To suppress this warning,
           say

               {
                   no warnings 'redefine';
                   eval "sub name { ... }";
               }

       Subroutine "%s" will not stay shared
           (W closure) An inner (nested) named subroutine is referencing a
           "my" subroutine defined in an outer named subroutine.

           When the inner subroutine is called, it will see the value of the
           outer subroutine's lexical subroutine as it was before and during
           the *first* call to the outer subroutine; in this case, after the
           first call to the outer subroutine is complete, the inner and outer
           subroutines will no longer share a common value for the lexical
           subroutine.  In other words, it will no longer be shared.  This
           will especially make a difference if the lexical subroutines
           accesses lexical variables declared in its surrounding scope.

           This problem can usually be solved by making the inner subroutine
           anonymous, using the "sub {}" syntax.  When inner anonymous subs
           that reference lexical subroutines in outer subroutines are
           created, they are automatically rebound to the current values of
           such lexical subs.

       Substitution loop
           (P) The substitution was looping infinitely.  (Obviously, a
           substitution shouldn't iterate more times than there are characters
           of input, which is what happened.)  See the discussion of
           substitution in "Regexp Quote-Like Operators" in perlop.

       Substitution pattern not terminated
           (F) The lexer couldn't find the interior delimiter of an s/// or
           s{}{} construct.  Remember that bracketing delimiters count nesting
           level.  Missing the leading "$" from variable $s may cause this
           error.

       Substitution replacement not terminated
           (F) The lexer couldn't find the final delimiter of an s/// or s{}{}
           construct.  Remember that bracketing delimiters count nesting
           level.  Missing the leading "$" from variable $s may cause this
           error.

       substr outside of string
           (W substr)(F) You tried to reference a substr() that pointed
           outside of a string.  That is, the absolute value of the offset was
           larger than the length of the string.  See "substr" in perlfunc.
           This warning is fatal if substr is used in an lvalue context (as
           the left hand side of an assignment or as a subroutine argument for
           example).

       sv_upgrade from type %d down to type %d
           (P) Perl tried to force the upgrade of an SV to a type which was
           actually inferior to its current type.

       Switch (?(condition)... contains too many branches in regex; marked by
       <-- HERE in m/%s/
           (F) A (?(condition)if-clause|else-clause) construct can have at
           most two branches (the if-clause and the else-clause).  If you want
           one or both to contain alternation, such as using
           "this|that|other", enclose it in clustering parentheses:

               (?(condition)(?:this|that|other)|else-clause)

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Switch condition not recognized in regex; marked by <-- HERE in m/%s/
           (F) The condition part of a (?(condition)if-clause|else-clause)
           construct is not known.  The condition must be one of the
           following:

            (1) (2) ...        true if 1st, 2nd, etc., capture matched
            (<NAME>) ('NAME')  true if named capture matched
            (?=...) (?<=...)   true if subpattern matches
            (?!...) (?<!...)   true if subpattern fails to match
            (?{ CODE })        true if code returns a true value
            (R)                true if evaluating inside recursion
            (R1) (R2) ...      true if directly inside capture group 1, 2, etc.
            (R&NAME)           true if directly inside named capture
            (DEFINE)           always false; for defining named subpatterns

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Switch (?(condition)... not terminated in regex; marked by <-- HERE in
       m/%s/
           (F) You omitted to close a (?(condition)...) block somewhere in the
           pattern.  Add a closing parenthesis in the appropriate position.
           See perlre.

       switching effective %s is not implemented
           (F) While under the "use filetest" pragma, we cannot switch the
           real and effective uids or gids.

       syntax error
           (F) Probably means you had a syntax error.  Common reasons include:

               A keyword is misspelled.
               A semicolon is missing.
               A comma is missing.
               An opening or closing parenthesis is missing.
               An opening or closing brace is missing.
               A closing quote is missing.

           Often there will be another error message associated with the
           syntax error giving more information.  (Sometimes it helps to turn
           on -w.)  The error message itself often tells you where it was in
           the line when it decided to give up.  Sometimes the actual error is
           several tokens before this, because Perl is good at understanding
           random input.  Occasionally the line number may be misleading, and
           once in a blue moon the only way to figure out what's triggering
           the error is to call "perl -c" repeatedly, chopping away half the
           program each time to see if the error went away.  Sort of the
           cybernetic version of 20 questions.

       syntax error at line %d: '%s' unexpected
           (A) You've accidentally run your script through the Bourne shell
           instead of Perl.  Check the #! line, or manually feed your script
           into Perl yourself.

       syntax error in file %s at line %d, next 2 tokens "%s"
           (F) This error is likely to occur if you run a perl5 script through
           a perl4 interpreter, especially if the next 2 tokens are "use
           strict" or "my $var" or "our $var".

       Syntax error in (?[...]) in regex; marked by <-- HERE in m/%s/
           (F) Perl could not figure out what you meant inside this construct;
           this notifies you that it is giving up trying.

       %s syntax OK
           (F) The final summary message when a "perl -c" succeeds.

       sysread() on closed filehandle %s
           (W closed) You tried to read from a closed filehandle.

       sysread() on unopened filehandle %s
           (W unopened) You tried to read from a filehandle that was never
           opened.

       System V %s is not implemented on this machine
           (F) You tried to do something with a function beginning with "sem",
           "shm", or "msg" but that System V IPC is not implemented in your
           machine.  In some machines the functionality can exist but be
           unconfigured.  Consult your system support.

       syswrite() on closed filehandle %s
           (W closed) The filehandle you're writing to got itself closed
           sometime before now.  Check your control flow.

       "-T" and "-B" not implemented on filehandles
           (F) Perl can't peek at the stdio buffer of filehandles when it
           doesn't know about your kind of stdio.  You'll have to use a
           filename instead.

       Target of goto is too deeply nested
           (F) You tried to use "goto" to reach a label that was too deeply
           nested for Perl to reach.  Perl is doing you a favor by refusing.

       telldir() attempted on invalid dirhandle %s
           (W io) The dirhandle you tried to telldir() is either closed or not
           really a dirhandle.  Check your control flow.

       tell() on unopened filehandle
           (W unopened) You tried to use the tell() function on a filehandle
           that was either never opened or has since been closed.

       The crypt() function is unimplemented due to excessive paranoia.
           (F) Configure couldn't find the crypt() function on your machine,
           probably because your vendor didn't supply it, probably because
           they think the U.S. Government thinks it's a secret, or at least
           that they will continue to pretend that it is.  And if you quote me
           on that, I will deny it.

       The experimental declared_refs feature is not enabled
           (F) To declare references to variables, as in "my \%x", you must
           first enable the feature:

               no warnings "experimental::declared_refs";
               use feature "declared_refs";

       The %s function is unimplemented
           (F) The function indicated isn't implemented on this architecture,
           according to the probings of Configure.

       The private_use feature is experimental
           (S experimental::private_use) This feature is actually a hook for
           future use.

       The regex_sets feature is experimental
           (S experimental::regex_sets) This warning is emitted if you use the
           syntax "(?[   ])" in a regular expression.  The details of this
           feature are subject to change.  If you want to use it, but know
           that in doing so you are taking the risk of using an experimental
           feature which may change in a future Perl version, you can do this
           to silence the warning:

               no warnings "experimental::regex_sets";

       The signatures feature is experimental
           (S experimental::signatures) This warning is emitted if you unwrap
           a subroutine's arguments using a signature.  Simply suppress the
           warning if you want to use the feature, but know that in doing so
           you are taking the risk of using an experimental feature which may
           change or be removed in a future Perl version:

               no warnings "experimental::signatures";
               use feature "signatures";
               sub foo ($left, $right) { ... }

       The stat preceding %s wasn't an lstat
           (F) It makes no sense to test the current stat buffer for symbolic
           linkhood if the last stat that wrote to the stat buffer already
           went past the symlink to get to the real file.  Use an actual
           filename instead.

       The Unicode property wildcards feature is experimental
           (S experimental::uniprop_wildcards) This feature is experimental
           and its behavior may in any future release of perl.  See "Wildcards
           in Property Values" in perlunicode.

       The 'unique' attribute may only be applied to 'our' variables
           (F) This attribute was never supported on "my" or "sub"
           declarations.

       This Perl can't reset CRTL environ elements (%s)
       This Perl can't set CRTL environ elements (%s=%s)
           (W internal) Warnings peculiar to VMS.  You tried to change or
           delete an element of the CRTL's internal environ array, but your
           copy of Perl wasn't built with a CRTL that contained the setenv()
           function.  You'll need to rebuild Perl with a CRTL that does, or
           redefine PERL_ENV_TABLES (see perlvms) so that the environ array
           isn't the target of the change to %ENV which produced the warning.

       This Perl has not been built with support for randomized hash key
       traversal but something called Perl_hv_rand_set().
           (F) Something has attempted to use an internal API call which
           depends on Perl being compiled with the default support for
           randomized hash key traversal, but this Perl has been compiled
           without it.  You should report this warning to the relevant
           upstream party, or recompile perl with default options.

       This use of my() in false conditional is no longer allowed
           (F) You used a declaration similar to "my $x if 0".  There has been
           a long-standing bug in Perl that causes a lexical variable not to
           be cleared at scope exit when its declaration includes a false
           conditional.  Some people have exploited this bug to achieve a kind
           of static variable.  Since we intend to fix this bug, we don't want
           people relying on this behavior.  You can achieve a similar static
           effect by declaring the variable in a separate block outside the
           function, eg

               sub f { my $x if 0; return $x++ }

           becomes

               { my $x; sub f { return $x++ } }

           Beginning with perl 5.10.0, you can also use "state" variables to
           have lexicals that are initialized only once (see feature):

               sub f { state $x; return $x++ }

           This use of "my()" in a false conditional was deprecated beginning
           in Perl 5.10 and became a fatal error in Perl 5.30.

       Timeout waiting for another thread to define \p{%s}
           (F) The first time a user-defined property ("User-Defined Character
           Properties" in perlunicode) is used, its definition is looked up
           and converted into an internal form for more efficient handling in
           subsequent uses.  There could be a race if two or more threads
           tried to do this processing nearly simultaneously.  Instead, a
           critical section is created around this task, locking out all but
           one thread from doing it.  This message indicates that the thread
           that is doing the conversion is taking an unexpectedly long time.
           The timeout exists solely to prevent deadlock; it's long enough
           that the system was likely thrashing and about to crash.  There is
           no real remedy but rebooting.

       times not implemented
           (F) Your version of the C library apparently doesn't do times().  I
           suspect you're not running on Unix.

       "-T" is on the #! line, it must also be used on the command line
           (X) The #! line (or local equivalent) in a Perl script contains the
           -T option (or the -t option), but Perl was not invoked with -T in
           its command line.  This is an error because, by the time Perl
           discovers a -T in a script, it's too late to properly taint
           everything from the environment.  So Perl gives up.

           If the Perl script is being executed as a command using the #!
           mechanism (or its local equivalent), this error can usually be
           fixed by editing the #! line so that the -%c option is a part of
           Perl's first argument: e.g. change "perl -n -%c" to "perl -%c -n".

           If the Perl script is being executed as "perl scriptname", then the
           -%c option must appear on the command line: "perl -%c scriptname".

       To%s: illegal mapping '%s'
           (F) You tried to define a customized To-mapping for lc(), lcfirst,
           uc(), or ucfirst() (or their string-inlined versions), but you
           specified an illegal mapping.  See "User-Defined Character
           Properties" in perlunicode.

       Too deeply nested ()-groups
           (F) Your template contains ()-groups with a ridiculously deep
           nesting level.

       Too few args to syscall
           (F) There has to be at least one argument to syscall() to specify
           the system call to call, silly dilly.

       Too few arguments for subroutine '%s' (got %d; expected %d)
           (F) A subroutine using a signature fewer arguments than required by
           the signature.  The caller of the subroutine is presumably at
           fault.

           The message attempts to include the name of the called subroutine.
           If the subroutine has been aliased, the subroutine's original name
           will be shown, regardless of what name the caller used. It will
           also indicate the number of arguments given and the number
           expected.

       Too few arguments for subroutine '%s' (got %d; expected at least %d)
           Similar to the previous message but for subroutines that accept a
           variable number of arguments.

       Too late for "-%s" option
           (X) The #! line (or local equivalent) in a Perl script contains the
           -M, -m or -C option.

           In the case of -M and -m, this is an error because those options
           are not intended for use inside scripts.  Use the "use" pragma
           instead.

           The -C option only works if it is specified on the command line as
           well (with the same sequence of letters or numbers following).
           Either specify this option on the command line, or, if your system
           supports it, make your script executable and run it directly
           instead of passing it to perl.

       Too late to run %s block
           (W void) A CHECK or INIT block is being defined during run time
           proper, when the opportunity to run them has already passed.
           Perhaps you are loading a file with "require" or "do" when you
           should be using "use" instead.  Or perhaps you should put the
           "require" or "do" inside a BEGIN block.

       Too many args to syscall
           (F) Perl supports a maximum of only 14 args to syscall().

       Too many arguments for %s
           (F) The function requires fewer arguments than you specified.

       Too many arguments for subroutine '%s' (got %d; expected %d)
           (F) A subroutine using a signature received more arguments than
           permitted by the signature.  The caller of the subroutine is
           presumably at fault.

           The message attempts to include the name of the called subroutine.
           If the subroutine has been aliased, the subroutine's original name
           will be shown, regardless of what name the caller used. It will
           also indicate the number of arguments given and the number
           expected.

       Too many arguments for subroutine '%s' (got %d; expected at most %d)
           Similar to the previous message but for subroutines that accept a
           variable number of arguments.

       Too many nested open parens in regex; marked by <-- HERE in m/%s/
           (F) You have exceeded the number of open "(" parentheses that
           haven't been matched by corresponding closing ones.  This limit
           prevents eating up too much memory.  It is initially set to 1000,
           but may be changed by setting "${^RE_COMPILE_RECURSION_LIMIT}" to
           some other value.  This may need to be done in a BEGIN block before
           the regular expression pattern is compiled.

       Too many )'s
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       Too many ('s
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       Trailing \ in regex m/%s/
           (F) The regular expression ends with an unbackslashed backslash.
           Backslash it.   See perlre.

       Transliteration pattern not terminated
           (F) The lexer couldn't find the interior delimiter of a tr/// or
           tr[][] or y/// or y[][] construct.  Missing the leading "$" from
           variables $tr or $y may cause this error.

       Transliteration replacement not terminated
           (F) The lexer couldn't find the final delimiter of a tr///, tr[][],
           y/// or y[][] construct.

       '%s' trapped by operation mask
           (F) You tried to use an operator from a Safe compartment in which
           it's disallowed.  See Safe.

       truncate not implemented
           (F) Your machine doesn't implement a file truncation mechanism that
           Configure knows about.

       try/catch is experimental
           (S experimental::try) This warning is emitted if you use the "try"
           and "catch" syntax. This syntax is currently experimental and its
           behaviour may change in future releases of Perl.

       Type of arg %d to &CORE::%s must be %s
           (F) The subroutine in question in the CORE package requires its
           argument to be a hard reference to data of the specified type.
           Overloading is ignored, so a reference to an object that is not the
           specified type, but nonetheless has overloading to handle it, will
           still not be accepted.

       Type of arg %d to %s must be %s (not %s)
           (F) This function requires the argument in that position to be of a
           certain type.  Arrays must be @NAME or "@{EXPR}".  Hashes must be
           %NAME or "%{EXPR}".  No implicit dereferencing is allowed--use the
           {EXPR} forms as an explicit dereference.  See perlref.

       umask not implemented
           (F) Your machine doesn't implement the umask function and you tried
           to use it to restrict permissions for yourself (EXPR & 0700).

       Unbalanced context: %d more PUSHes than POPs
           (S internal) The exit code detected an internal inconsistency in
           how many execution contexts were entered and left.

       Unbalanced saves: %d more saves than restores
           (S internal) The exit code detected an internal inconsistency in
           how many values were temporarily localized.

       Unbalanced scopes: %d more ENTERs than LEAVEs
           (S internal) The exit code detected an internal inconsistency in
           how many blocks were entered and left.

       Unbalanced string table refcount: (%d) for "%s"
           (S internal) On exit, Perl found some strings remaining in the
           shared string table used for copy on write and for hash keys.  The
           entries should have been freed, so this indicates a bug somewhere.

       Unbalanced tmps: %d more allocs than frees
           (S internal) The exit code detected an internal inconsistency in
           how many mortal scalars were allocated and freed.

       Undefined format "%s" called
           (F) The format indicated doesn't seem to exist.  Perhaps it's
           really in another package?  See perlform.

       Undefined sort subroutine "%s" called
           (F) The sort comparison routine specified doesn't seem to exist.
           Perhaps it's in a different package?  See "sort" in perlfunc.

       Undefined subroutine &%s called
           (F) The subroutine indicated hasn't been defined, or if it was, it
           has since been undefined.

       Undefined subroutine called
           (F) The anonymous subroutine you're trying to call hasn't been
           defined, or if it was, it has since been undefined.

       Undefined subroutine in sort
           (F) The sort comparison routine specified is declared but doesn't
           seem to have been defined yet.  See "sort" in perlfunc.

       Undefined top format "%s" called
           (F) The format indicated doesn't seem to exist.  Perhaps it's
           really in another package?  See perlform.

       Undefined value assigned to typeglob
           (W misc) An undefined value was assigned to a typeglob, a la "*foo
           = undef".  This does nothing.  It's possible that you really mean
           "undef *foo".

       %s: Undefined variable
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       Unescaped left brace in regex is illegal here in regex; marked by
       <-- HERE in m/%s/
           (F) The simple rule to remember, if you want to match a literal "{"
           character (U+007B "LEFT CURLY BRACKET") in a regular expression
           pattern, is to escape each literal instance of it in some way.
           Generally easiest is to precede it with a backslash, like "\{" or
           enclose it in square brackets ("[{]").  If the pattern delimiters
           are also braces, any matching right brace ("}") should also be
           escaped to avoid confusing the parser, for example,

            qr{abc\{def\}ghi}

           Forcing literal "{" characters to be escaped enables the Perl
           language to be extended in various ways in future releases.  To
           avoid needlessly breaking existing code, the restriction is not
           enforced in contexts where there are unlikely to ever be extensions
           that could conflict with the use there of "{" as a literal.  Those
           that are not potentially ambiguous do not warn; those that are do
           raise a non-deprecation warning.

           The contexts where no warnings or errors are raised are:

           o   as the first character in a pattern, or following "^"
               indicating to anchor the match to the beginning of a line.

           o   as the first character following a "|" indicating alternation.

           o   as the first character in a parenthesized grouping like

                /foo({bar)/
                /foo(?:{bar)/

           o   as the first character following a quantifier

                /\s*{/

       Unescaped left brace in regex is passed through in regex; marked by
       <-- HERE in m/%s/
           (W regexp)  The simple rule to remember, if you want to match a
           literal "{" character (U+007B "LEFT CURLY BRACKET") in a regular
           expression pattern, is to escape each literal instance of it in
           some way.  Generally easiest is to precede it with a backslash,
           like "\{" or enclose it in square brackets ("[{]").  If the pattern
           delimiters are also braces, any matching right brace ("}") should
           also be escaped to avoid confusing the parser, for example,

            qr{abc\{def\}ghi}

           Forcing literal "{" characters to be escaped enables the Perl
           language to be extended in various ways in future releases.  To
           avoid needlessly breaking existing code, the restriction is not
           enforced in contexts where there are unlikely to ever be extensions
           that could conflict with the use there of "{" as a literal.  Those
           that are not potentially ambiguous do not warn; those that are
           raise this warning.  This makes sure that an inadvertent typo
           doesn't silently cause the pattern to compile to something
           unintended.

           The contexts where no warnings or errors are raised are:

           o   as the first character in a pattern, or following "^"
               indicating to anchor the match to the beginning of a line.

           o   as the first character following a "|" indicating alternation.

           o   as the first character in a parenthesized grouping like

                /foo({bar)/
                /foo(?:{bar)/

           o   as the first character following a quantifier

                /\s*{/

       Unescaped literal '%c' in regex; marked by <-- HERE in m/%s/
           (W regexp) (only under "use re 'strict'")

           Within the scope of "use re 'strict'" in a regular expression
           pattern, you included an unescaped "}" or "]" which was interpreted
           literally.  These two characters are sometimes metacharacters, and
           sometimes literals, depending on what precedes them in the pattern.
           This is unlike the similar ")" which is always a metacharacter
           unless escaped.

           This action at a distance, perhaps a large distance, can lead to
           Perl silently misinterpreting what you meant, so when you specify
           that you want extra checking by "use re 'strict'", this warning is
           generated.  If you meant the character as a literal, simply confirm
           that to Perl by preceding the character with a backslash, or make
           it into a bracketed character class (like "[}]").  If you meant it
           as closing a corresponding "[" or "{", you'll need to look back
           through the pattern to find out why that isn't happening.

       unexec of %s into %s failed!
           (F) The unexec() routine failed for some reason.  See your local
           FSF representative, who probably put it there in the first place.

       Unexpected binary operator '%c' with no preceding operand in regex;
       marked by <-- HERE in m/%s/
           (F) You had something like this:

            (?[ | \p{Digit} ])

           where the "|" is a binary operator with an operand on the right,
           but no operand on the left.

       Unexpected character in regex; marked by <-- HERE in m/%s/
           (F) You had something like this:

            (?[ z ])

           Within "(?[ ])", no literal characters are allowed unless they are
           within an inner pair of square brackets, like

            (?[ [ z ] ])

           Another possibility is that you forgot a backslash.  Perl isn't
           smart enough to figure out what you really meant.

       Unexpected constant lvalue entersub entry via type/targ %d:%d
           (P) When compiling a subroutine call in lvalue context, Perl failed
           an internal consistency check.  It encountered a malformed op tree.

       Unexpected exit %u
           (S) exit() was called or the script otherwise finished gracefully
           when "PERL_EXIT_WARN" was set in "PL_exit_flags".

       Unexpected exit failure %d
           (S) An uncaught die() was called when "PERL_EXIT_WARN" was set in
           "PL_exit_flags".

       Unexpected ')' in regex; marked by <-- HERE in m/%s/
           (F) You had something like this:

            (?[ ( \p{Digit} + ) ])

           The ")" is out-of-place.  Something apparently was supposed to be
           combined with the digits, or the "+" shouldn't be there, or
           something like that.  Perl can't figure out what was intended.

       Unexpected ']' with no following ')' in (?[... in regex; marked by <--
       HERE in m/%s/
           (F) While parsing an extended character class a ']' character was
           encountered at a point in the definition where the only legal use
           of ']' is to close the character class definition as part of a
           '])', you may have forgotten the close paren, or otherwise confused
           the parser.

       Unexpected '(' with no preceding operator in regex; marked by <-- HERE
       in m/%s/
           (F) You had something like this:

            (?[ \p{Digit} ( \p{Lao} + \p{Thai} ) ])

           There should be an operator before the "(", as there's no
           indication as to how the digits are to be combined with the
           characters in the Lao and Thai scripts.

       Unicode non-character U+%X is not recommended for open interchange
           (S nonchar) Certain codepoints, such as U+FFFE and U+FFFF, are
           defined by the Unicode standard to be non-characters.  Those are
           legal codepoints, but are reserved for internal use; so,
           applications shouldn't attempt to exchange them.  An application
           may not be expecting any of these characters at all, and receiving
           them may lead to bugs.  If you know what you are doing you can turn
           off this warning by "no warnings 'nonchar';".

           This is not really a "severe" error, but it is supposed to be
           raised by default even if warnings are not enabled, and currently
           the only way to do that in Perl is to mark it as serious.

       Unicode property wildcard not terminated
           (F) A Unicode property wildcard looks like a delimited regular
           expression pattern (all within the braces of the enclosing
           "\p{...}".  The closing delimtter to match the opening one was not
           found.  If the opening one is escaped by preceding it with a
           backslash, the closing one must also be so escaped.

       Unicode string properties are not implemented in (?[...]) in regex;
       marked by <-- HERE in m/%s/
           (F) A Unicode string property is one which expands to a sequence of
           multiple characters.  An example is "\p{name=KATAKANA LETTER AINU
           P}", which is comprised of the sequence "\N{KATAKANA LETTER SMALL
           H}" followed by "\N{COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND
           MARK}".  Extended character classes, "(?[...])" currently cannot
           handle these.

       Unicode surrogate U+%X is illegal in UTF-8
           (S surrogate) You had a UTF-16 surrogate in a context where they
           are not considered acceptable.  These code points, between U+D800
           and U+DFFF (inclusive), are used by Unicode only for UTF-16.
           However, Perl internally allows all unsigned integer code points
           (up to the size limit available on your platform), including
           surrogates.  But these can cause problems when being input or
           output, which is likely where this message came from.  If you
           really really know what you are doing you can turn off this warning
           by "no warnings 'surrogate';".

       Unknown charname '%s'
           (F) The name you used inside "\N{}" is unknown to Perl.  Check the
           spelling.  You can say "use charnames ":loose"" to not have to be
           so precise about spaces, hyphens, and capitalization on standard
           Unicode names.  (Any custom aliases that have been created must be
           specified exactly, regardless of whether ":loose" is used or not.)
           This error may also happen if the "\N{}" is not in the scope of the
           corresponding "use charnames".

       Unknown '(*...)' construct '%s' in regex; marked by <-- HERE in m/%s/
           (F) The "(*" was followed by something that the regular expression
           compiler does not recognize.  Check your spelling.

       Unknown error
           (P) Perl was about to print an error message in $@, but the $@
           variable did not exist, even after an attempt to create it.

       Unknown locale category %d; can't set it to %s
           (W locale) You used a locale category that perl doesn't recognize,
           so it cannot carry out your request.  Check that you are using a
           valid category.  If so, see "Multi-threaded" in perllocale for
           advice on reporting this as a bug, and for modifying perl locally
           to accommodate your needs.

       Unknown open() mode '%s'
           (F) The second argument of 3-argument open() is not among the list
           of valid modes: "<", ">", ">>", "+<", "+>", "+>>", "-|", "|-",
           "<&", ">&".

       Unknown PerlIO layer "%s"
           (W layer) An attempt was made to push an unknown layer onto the
           Perl I/O system.  (Layers take care of transforming data between
           external and internal representations.)  Note that some layers,
           such as "mmap", are not supported in all environments.  If your
           program didn't explicitly request the failing operation, it may be
           the result of the value of the environment variable PERLIO.

       Unknown process %x sent message to prime_env_iter: %s
           (P) An error peculiar to VMS.  Perl was reading values for %ENV
           before iterating over it, and someone else stuck a message in the
           stream of data Perl expected.  Someone's very confused, or perhaps
           trying to subvert Perl's population of %ENV for nefarious purposes.

       Unknown regexp modifier "/%s"
           (F) Alphanumerics immediately following the closing delimiter of a
           regular expression pattern are interpreted by Perl as modifier
           flags for the regex.  One of the ones you specified is invalid.
           One way this can happen is if you didn't put in white space between
           the end of the regex and a following alphanumeric operator:

            if ($a =~ /foo/and $bar == 3) { ... }

           The "a" is a valid modifier flag, but the "n" is not, and raises
           this error.  Likely what was meant instead was:

            if ($a =~ /foo/ and $bar == 3) { ... }

       Unknown "re" subpragma '%s' (known ones are: %s)
           (W) You tried to use an unknown subpragma of the "re" pragma.

       Unknown switch condition (?(...)) in regex; marked by <-- HERE in m/%s/
           (F) The condition part of a (?(condition)if-clause|else-clause)
           construct is not known.  The condition must be one of the
           following:

            (1) (2) ...            true if 1st, 2nd, etc., capture matched
            (<NAME>) ('NAME')      true if named capture matched
            (?=...) (?<=...)       true if subpattern matches
            (*pla:...) (*plb:...)  true if subpattern matches; also
                                        (*positive_lookahead:...)
                                        (*positive_lookbehind:...)
            (*nla:...) (*nlb:...)  true if subpattern fails to match; also
                                        (*negative_lookahead:...)
                                        (*negative_lookbehind:...)
            (?{ CODE })            true if code returns a true value
            (R)                    true if evaluating inside recursion
            (R1) (R2) ...          true if directly inside capture group 1, 2,
                                        etc.
            (R&NAME)               true if directly inside named capture
            (DEFINE)               always false; for defining named subpatterns

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Unknown Unicode option letter '%c'
           (F) You specified an unknown Unicode option.  See perlrun
           documentation of the "-C" switch for the list of known options.

       Unknown Unicode option value %d
           (F) You specified an unknown Unicode option.  See perlrun
           documentation of the "-C" switch for the list of known options.

       Unknown user-defined property name \p{%s}
           (F) You specified to use a property within the "\p{...}" which was
           a syntactically valid user-defined property, but no definition was
           found for it by the time one was required to proceed.  Check your
           spelling.  See "User-Defined Character Properties" in perlunicode.

       Unknown verb pattern '%s' in regex; marked by <-- HERE in m/%s/
           (F) You either made a typo or have incorrectly put a "*" quantifier
           after an open brace in your pattern.  Check the pattern and review
           perlre for details on legal verb patterns.

       Unknown warnings category '%s'
           (F) An error issued by the "warnings" pragma.  You specified a
           warnings category that is unknown to perl at this point.

           Note that if you want to enable a warnings category registered by a
           module (e.g. "use warnings 'File::Find'"), you must have loaded
           this module first.

       Unmatched [ in regex; marked by <-- HERE in m/%s/
           (F) The brackets around a character class must match.  If you wish
           to include a closing bracket in a character class, backslash it or
           put it first.  The <-- HERE shows whereabouts in the regular
           expression the problem was discovered.  See perlre.

       Unmatched ( in regex; marked by <-- HERE in m/%s/
       Unmatched ) in regex; marked by <-- HERE in m/%s/
           (F) Unbackslashed parentheses must always be balanced in regular
           expressions.  If you're a vi user, the % key is valuable for
           finding the matching parenthesis.  The <-- HERE shows whereabouts
           in the regular expression the problem was discovered.  See perlre.

       Unmatched right %s bracket
           (F) The lexer counted more closing curly or square brackets than
           opening ones, so you're probably missing a matching opening
           bracket.  As a general rule, you'll find the missing one (so to
           speak) near the place you were last editing.

       Unquoted string "%s" may clash with future reserved word
           (W reserved) You used a bareword that might someday be claimed as a
           reserved word.  It's best to put such a word in quotes, or
           capitalize it somehow, or insert an underbar into it.  You might
           also declare it as a subroutine.

       Unrecognized character %s; marked by <-- HERE after %s near column %d
           (F) The Perl parser has no idea what to do with the specified
           character in your Perl script (or eval) near the specified column.
           Perhaps you tried  to run a compressed script, a binary program, or
           a directory as a Perl program.

       Unrecognized escape \%c in character class in regex; marked by <-- HERE
       in m/%s/
           (F) You used a backslash-character combination which is not
           recognized by Perl inside character classes.  This is a fatal error
           when the character class is used within "(?[ ])".

       Unrecognized escape \%c in character class passed through in regex;
       marked by <-- HERE in m/%s/
           (W regexp) You used a backslash-character combination which is not
           recognized by Perl inside character classes.  The character was
           understood literally, but this may change in a future version of
           Perl.  The <-- HERE shows whereabouts in the regular expression the
           escape was discovered.

       Unrecognized escape \%c passed through
           (W misc) You used a backslash-character combination which is not
           recognized by Perl.  The character was understood literally, but
           this may change in a future version of Perl.

       Unrecognized escape \%s passed through in regex; marked by <-- HERE in
       m/%s/
           (W regexp) You used a backslash-character combination which is not
           recognized by Perl.  The character(s) were understood literally,
           but this may change in a future version of Perl.  The <-- HERE
           shows whereabouts in the regular expression the escape was
           discovered.

       Unrecognized signal name "%s"
           (F) You specified a signal name to the kill() function that was not
           recognized.  Say "kill -l" in your shell to see the valid signal
           names on your system.

       Unrecognized switch: -%s  (-h will show valid options)
           (F) You specified an illegal option to Perl.  Don't do that.  (If
           you think you didn't do that, check the #! line to see if it's
           supplying the bad switch on your behalf.)

       Unsuccessful %s on filename containing newline
           (W newline) A file operation was attempted on a filename, and that
           operation failed, PROBABLY because the filename contained a
           newline, PROBABLY because you forgot to chomp() it off.  See
           "chomp" in perlfunc.

       Unsupported directory function "%s" called
           (F) Your machine doesn't support opendir() and readdir().

       Unsupported function %s
           (F) This machine doesn't implement the indicated function,
           apparently.  At least, Configure doesn't think so.

       Unsupported function fork
           (F) Your version of executable does not support forking.

           Note that under some systems, like OS/2, there may be different
           flavors of Perl executables, some of which may support fork, some
           not.  Try changing the name you call Perl by to "perl_", "perl__",
           and so on.

       Unsupported script encoding %s
           (F) Your program file begins with a Unicode Byte Order Mark (BOM)
           which declares it to be in a Unicode encoding that Perl cannot
           read.

       Unsupported socket function "%s" called
           (F) Your machine doesn't support the Berkeley socket mechanism, or
           at least that's what Configure thought.

       Unterminated '(*...' argument in regex; marked by <-- HERE in m/%s/
           (F) You used a pattern of the form "(*...:...)" but did not
           terminate the pattern with a ")".  Fix the pattern and retry.

       Unterminated attribute list
           (F) The lexer found something other than a simple identifier at the
           start of an attribute, and it wasn't a semicolon or the start of a
           block.  Perhaps you terminated the parameter list of the previous
           attribute too soon.  See attributes.

       Unterminated attribute parameter in attribute list
           (F) The lexer saw an opening (left) parenthesis character while
           parsing an attribute list, but the matching closing (right)
           parenthesis character was not found.  You may need to add (or
           remove) a backslash character to get your parentheses to balance.
           See attributes.

       Unterminated compressed integer
           (F) An argument to unpack("w",...) was incompatible with the BER
           compressed integer format and could not be converted to an integer.
           See "pack" in perlfunc.

       Unterminated '(*...' construct in regex; marked by <-- HERE in m/%s/
           (F) You used a pattern of the form "(*...)" but did not terminate
           the pattern with a ")".  Fix the pattern and retry.

       Unterminated delimiter for here document
           (F) This message occurs when a here document label has an initial
           quotation mark but the final quotation mark is missing.  Perhaps
           you wrote:

               <<"foo

           instead of:

               <<"foo"

       Unterminated \g... pattern in regex; marked by <-- HERE in m/%s/
       Unterminated \g{...} pattern in regex; marked by <-- HERE in m/%s/
           (F) In a regular expression, you had a "\g" that wasn't followed by
           a proper group reference.  In the case of "\g{", the closing brace
           is missing; otherwise the "\g" must be followed by an integer.  Fix
           the pattern and retry.

       Unterminated <> operator
           (F) The lexer saw a left angle bracket in a place where it was
           expecting a term, so it's looking for the corresponding right angle
           bracket, and not finding it.  Chances are you left some needed
           parentheses out earlier in the line, and you really meant a "less
           than".

       Unterminated verb pattern argument in regex; marked by <-- HERE in
       m/%s/
           (F) You used a pattern of the form "(*VERB:ARG)" but did not
           terminate the pattern with a ")".  Fix the pattern and retry.

       Unterminated verb pattern in regex; marked by <-- HERE in m/%s/
           (F) You used a pattern of the form "(*VERB)" but did not terminate
           the pattern with a ")".  Fix the pattern and retry.

       untie attempted while %d inner references still exist
           (W untie) A copy of the object returned from "tie" (or "tied") was
           still valid when "untie" was called.

       Usage: POSIX::%s(%s)
           (F) You called a POSIX function with incorrect arguments.  See
           "FUNCTIONS" in POSIX for more information.

       Usage: Win32::%s(%s)
           (F) You called a Win32 function with incorrect arguments.  See
           Win32 for more information.

       $[ used in %s (did you mean $] ?)
           (W syntax) You used $[ in a comparison, such as:

               if ($[ > 5.006) {
                   ...
               }

           You probably meant to use $] instead.  $[ is the base for indexing
           arrays.  $] is the Perl version number in decimal.

       Use "%s" instead of "%s"
           (F) The second listed construct is no longer legal.  Use the first
           one instead.

       Useless assignment to a temporary
           (W misc) You assigned to an lvalue subroutine, but what the
           subroutine returned was a temporary scalar about to be discarded,
           so the assignment had no effect.

       Useless (?-%s) - don't use /%s modifier in regex; marked by <-- HERE in
       m/%s/
           (W regexp) You have used an internal modifier such as (?-o) that
           has no meaning unless removed from the entire regexp:

               if ($string =~ /(?-o)$pattern/o) { ... }

           must be written as

               if ($string =~ /$pattern/) { ... }

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Useless localization of %s
           (W syntax) The localization of lvalues such as "local($x=10)" is
           legal, but in fact the local() currently has no effect.  This may
           change at some point in the future, but in the meantime such code
           is discouraged.

       Useless (?%s) - use /%s modifier in regex; marked by <-- HERE in m/%s/
           (W regexp) You have used an internal modifier such as (?o) that has
           no meaning unless applied to the entire regexp:

               if ($string =~ /(?o)$pattern/) { ... }

           must be written as

               if ($string =~ /$pattern/o) { ... }

           The <-- HERE shows whereabouts in the regular expression the
           problem was discovered.  See perlre.

       Useless use of attribute "const"
           (W misc) The "const" attribute has no effect except on anonymous
           closure prototypes.  You applied it to a subroutine via
           attributes.pm.  This is only useful inside an attribute handler for
           an anonymous subroutine.

       Useless use of /d modifier in transliteration operator
           (W misc) You have used the /d modifier where the searchlist has the
           same length as the replacelist.  See perlop for more information
           about the /d modifier.

       Useless use of \E
           (W misc) You have a \E in a double-quotish string without a "\U",
           "\L" or "\Q" preceding it.

       Useless use of greediness modifier '%c' in regex; marked by <-- HERE in
       m/%s/
           (W regexp) You specified something like these:

            qr/a{3}?/
            qr/b{1,1}+/

           The "?" and "+" don't have any effect, as they modify whether to
           match more or fewer when there is a choice, and by specifying to
           match exactly a given numer, there is no room left for a choice.

       Useless use of %s in void context
           (W void) You did something without a side effect in a context that
           does nothing with the return value, such as a statement that
           doesn't return a value from a block, or the left side of a scalar
           comma operator.  Very often this points not to stupidity on your
           part, but a failure of Perl to parse your program the way you
           thought it would.  For example, you'd get this if you mixed up your
           C precedence with Python precedence and said

               $one, $two = 1, 2;

           when you meant to say

               ($one, $two) = (1, 2);

           Another common error is to use ordinary parentheses to construct a
           list reference when you should be using square or curly brackets,
           for example, if you say

               $array = (1,2);

           when you should have said

               $array = [1,2];

           The square brackets explicitly turn a list value into a scalar
           value, while parentheses do not.  So when a parenthesized list is
           evaluated in a scalar context, the comma is treated like C's comma
           operator, which throws away the left argument, which is not what
           you want.  See perlref for more on this.

           This warning will not be issued for numerical constants equal to 0
           or 1 since they are often used in statements like

               1 while sub_with_side_effects();

           String constants that would normally evaluate to 0 or 1 are warned
           about.

       Useless use of (?-p) in regex; marked by <-- HERE in m/%s/
           (W regexp) The "p" modifier cannot be turned off once set.  Trying
           to do so is futile.

       Useless use of "re" pragma
           (W) You did "use re;" without any arguments.  That isn't very
           useful.

       Useless use of sort in scalar context
           (W void) You used sort in scalar context, as in :

               my $x = sort @y;

           This is not very useful, and perl currently optimizes this away.

       Useless use of %s with no values
           (W syntax) You used the push() or unshift() function with no
           arguments apart from the array, like "push(@x)" or "unshift(@foo)".
           That won't usually have any effect on the array, so is completely
           useless.  It's possible in principle that push(@tied_array) could
           have some effect if the array is tied to a class which implements a
           PUSH method.  If so, you can write it as "push(@tied_array,())" to
           avoid this warning.

       "use" not allowed in expression
           (F) The "use" keyword is recognized and executed at compile time,
           and returns no useful value.  See perlmod.

       Use of bare << to mean <<"" is forbidden
           (F) You are now required to use the explicitly quoted form if you
           wish to use an empty line as the terminator of the here-document.

           Use of a bare terminator was deprecated in Perl 5.000, and is a
           fatal error as of Perl 5.28.

       Use of /c modifier is meaningless in s///
           (W regexp) You used the /c modifier in a substitution.  The /c
           modifier is not presently meaningful in substitutions.

       Use of /c modifier is meaningless without /g
           (W regexp) You used the /c modifier with a regex operand, but
           didn't use the /g modifier.  Currently, /c is meaningful only when
           /g is used.  (This may change in the future.)

       Use of code point 0x%s is not allowed; the permissible max is 0x%X
       Use of code point 0x%s is not allowed; the permissible max is 0x%X in
       regex; marked by <-- HERE in m/%s/
           (F) You used a code point that is not allowed, because it is too
           large.  Unicode only allows code points up to 0x10FFFF, but Perl
           allows much larger ones. Earlier versions of Perl allowed code
           points above IV_MAX (0x7FFFFFF on 32-bit platforms,
           0x7FFFFFFFFFFFFFFF on 64-bit platforms), however, this could
           possibly break the perl interpreter in some constructs, including
           causing it to hang in a few cases.

           If your code is to run on various platforms, keep in mind that the
           upper limit depends on the platform.  It is much larger on 64-bit
           word sizes than 32-bit ones.

           The use of out of range code points was deprecated in Perl 5.24,
           and became a fatal error in Perl 5.28.

       Use of each() on hash after insertion without resetting hash iterator
       results in undefined behavior
           (S internal) The behavior of "each()" after insertion is undefined;
           it may skip items, or visit items more than once.  Consider using
           "keys()" instead of "each()".

       Use of := for an empty attribute list is not allowed
           (F) The construction "my $x := 42" used to parse as equivalent to
           "my $x : = 42" (applying an empty attribute list to $x).  This
           construct was deprecated in 5.12.0, and has now been made a syntax
           error, so ":=" can be reclaimed as a new operator in the future.

           If you need an empty attribute list, for example in a code
           generator, add a space before the "=".

       Use of %s for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale
           (W locale)  You are matching a regular expression using locale
           rules, and the specified construct was encountered.  This construct
           is only valid for UTF-8 locales, which the current locale isn't.
           This doesn't make sense.  Perl will continue, assuming a Unicode
           (UTF-8) locale, but the results are likely to be wrong.

       Use of freed value in iteration
           (F) Perhaps you modified the iterated array within the loop?  This
           error is typically caused by code like the following:

               @a = (3,4);
               @a = () for (1,2,@a);

           You are not supposed to modify arrays while they are being iterated
           over.  For speed and efficiency reasons, Perl internally does not
           do full reference-counting of iterated items, hence deleting such
           an item in the middle of an iteration causes Perl to see a freed
           value.

       Use of /g modifier is meaningless in split
           (W regexp) You used the /g modifier on the pattern for a "split"
           operator.  Since "split" always tries to match the pattern
           repeatedly, the "/g" has no effect.

       Use of "goto" to jump into a construct is deprecated
           (D deprecated) Using "goto" to jump from an outer scope into an
           inner scope is deprecated and should be avoided.

           This was deprecated in Perl 5.12.

       Use of '%s' in \p{} or \P{} is deprecated because: %s
           (D deprecated) Certain properties are deprecated by Unicode, and
           may eventually be removed from the Standard, at which time Perl
           will follow along.  In the meantime, this message is raised to
           notify you.

       Use of inherited AUTOLOAD for non-method %s::%s() is no longer allowed
           (F) As an accidental feature, "AUTOLOAD" subroutines were looked up
           as methods (using the @ISA hierarchy), even when the subroutines to
           be autoloaded were called as plain functions (e.g. "Foo::bar()"),
           not as methods (e.g. "Foo->bar()" or "$obj->bar()").

           This was deprecated in Perl 5.004, and was made fatal in Perl 5.28.

       Use of %s in printf format not supported
           (F) You attempted to use a feature of printf that is accessible
           from only C.  This usually means there's a better way to do it in
           Perl.

       Use of %s is not allowed in Unicode property wildcard subpatterns in
       regex; marked by <-- HERE in m/%s/
           (F) You were using a wildcard subpattern a Unicode property value,
           and the subpattern contained something that is illegal.  Not all
           regular expression capabilities are legal in such subpatterns, and
           this is one.  Rewrite your subppattern to not use the offending
           construct.  See "Wildcards in Property Values" in perlunicode.

       Use of -l on filehandle%s
           (W io) A filehandle represents an opened file, and when you opened
           the file it already went past any symlink you are presumably trying
           to look for.  The operation returned "undef".  Use a filename
           instead.

       Use of reference "%s" as array index
           (W misc) You tried to use a reference as an array index; this
           probably isn't what you mean, because references in numerical
           context tend to be huge numbers, and so usually indicates
           programmer error.

           If you really do mean it, explicitly numify your reference, like
           so: $array[0+$ref].  This warning is not given for overloaded
           objects, however, because you can overload the numification and
           stringification operators and then you presumably know what you are
           doing.

       Use of strings with code points over 0xFF as arguments to %s operator
       is not allowed
           (F) You tried to use one of the string bitwise operators ("&" or
           "|" or "^" or "~") on a string containing a code point over 0xFF.
           The string bitwise operators treat their operands as strings of
           bytes, and values beyond 0xFF are nonsensical in this context.

           Certain instances became fatal in Perl 5.28; others in perl 5.32.

       Use of strings with code points over 0xFF as arguments to vec is
       forbidden
           (F) You tried to use "vec" on a string containing a code point over
           0xFF, which is nonsensical here.

           This became fatal in Perl 5.32.

       Use of tainted arguments in %s is deprecated
           (W taint, deprecated) You have supplied "system()" or "exec()" with
           multiple arguments and at least one of them is tainted.  This used
           to be allowed but will become a fatal error in a future version of
           perl.  Untaint your arguments.  See perlsec.

       Use of unassigned code point or non-standalone grapheme for a delimiter
       is not allowed
           (F) A grapheme is what appears to a native-speaker of a language to
           be a character.  In Unicode (and hence Perl) a grapheme may
           actually be several adjacent characters that together form a
           complete grapheme.  For example, there can be a base character,
           like "R" and an accent, like a circumflex "^", that appear when
           displayed to be a single character with the circumflex hovering
           over the "R".  Perl currently allows things like that circumflex to
           be delimiters of strings, patterns, etc.  When displayed, the
           circumflex would look like it belongs to the character just to the
           left of it.  In order to move the language to be able to accept
           graphemes as delimiters, we cannot allow the use of delimiters
           which aren't graphemes by themselves.  Also, a delimiter must
           already be assigned (or known to be never going to be assigned) to
           try to future-proof code, for otherwise code that works today would
           fail to compile if the currently unassigned delimiter ends up being
           something that isn't a stand-alone grapheme.  Because Unicode is
           never going to assign non-character code points, nor code points
           that are above the legal Unicode maximum, those can be delimiters,
           and their use is legal.

       Use of uninitialized value%s
           (W uninitialized) An undefined value was used as if it were already
           defined.  It was interpreted as a "" or a 0, but maybe it was a
           mistake.  To suppress this warning assign a defined value to your
           variables.

           To help you figure out what was undefined, perl will try to tell
           you the name of the variable (if any) that was undefined.  In some
           cases it cannot do this, so it also tells you what operation you
           used the undefined value in.  Note, however, that perl optimizes
           your program and the operation displayed in the warning may not
           necessarily appear literally in your program.  For example, "that
           $foo" is usually optimized into ""that " . $foo", and the warning
           will refer to the "concatenation (.)" operator, even though there
           is no "." in your program.

       "use re 'strict'" is experimental
           (S experimental::re_strict) The things that are different when a
           regular expression pattern is compiled under 'strict' are subject
           to change in future Perl releases in incompatible ways.  This means
           that a pattern that compiles today may not in a future Perl
           release.  This warning is to alert you to that risk.

       Use \x{...} for more than two hex characters in regex; marked by
       <-- HERE in m/%s/
           (F) In a regular expression, you said something like

            (?[ [ \xBEEF ] ])

           Perl isn't sure if you meant this

            (?[ [ \x{BEEF} ] ])

           or if you meant this

            (?[ [ \x{BE} E F ] ])

           You need to add either braces or blanks to disambiguate.

       Using just the first character returned by \N{} in character class in
       regex; marked by <-- HERE in m/%s/
           (W regexp) Named Unicode character escapes "(\N{...})" may return a
           multi-character sequence.  Even though a character class is
           supposed to match just one character of input, perl will match the
           whole thing correctly, except when the class is inverted
           ("[^...]"), or the escape is the beginning or final end point of a
           range.  For these, what should happen isn't clear at all.  In these
           circumstances, Perl discards all but the first character of the
           returned sequence, which is not likely what you want.

       Using just the single character results returned by \p{} in (?[...]) in
       regex; marked by <-- HERE in m/%s/
           (W regexp) Extended character classes currently cannot handle
           operands that evaluate to more than one character.  These are
           removed from the results of the expansion of the "\p{}".

           This situation can happen, for example, in

            (?[ \p{name=/KATAKANA/} ])

           "KATAKANA LETTER AINU P" is a legal Unicode name (technically a
           "named sequence"), but it is actually two characters.  The above
           expression with match only the Unicode names containing KATAKANA
           that represent single characters.

       Using /u for '%s' instead of /%s in regex; marked by <-- HERE in m/%s/
           (W regexp) You used a Unicode boundary ("\b{...}" or "\B{...}") in
           a portion of a regular expression where the character set modifiers
           "/a" or "/aa" are in effect.  These two modifiers indicate an ASCII
           interpretation, and this doesn't make sense for a Unicode
           definition.  The generated regular expression will compile so that
           the boundary uses all of Unicode.  No other portion of the regular
           expression is affected.

       Using !~ with %s doesn't make sense
           (F) Using the "!~" operator with "s///r", "tr///r" or "y///r" is
           currently reserved for future use, as the exact behavior has not
           been decided.  (Simply returning the boolean opposite of the
           modified string is usually not particularly useful.)

       UTF-16 surrogate U+%X
           (S surrogate) You had a UTF-16 surrogate in a context where they
           are not considered acceptable.  These code points, between U+D800
           and U+DFFF (inclusive), are used by Unicode only for UTF-16.
           However, Perl internally allows all unsigned integer code points
           (up to the size limit available on your platform), including
           surrogates.  But these can cause problems when being input or
           output, which is likely where this message came from.  If you
           really really know what you are doing you can turn off this warning
           by "no warnings 'surrogate';".

       Value of %s can be "0"; test with defined()
           (W misc) In a conditional expression, you used <HANDLE>, <*>
           (glob), "each()", or "readdir()" as a boolean value.  Each of these
           constructs can return a value of "0"; that would make the
           conditional expression false, which is probably not what you
           intended.  When using these constructs in conditional expressions,
           test their values with the "defined" operator.

       Value of CLI symbol "%s" too long
           (W misc) A warning peculiar to VMS.  Perl tried to read the value
           of an %ENV element from a CLI symbol table, and found a resultant
           string longer than 1024 characters.  The return value has been
           truncated to 1024 characters.

       Variable "%s" is not available
           (W closure) During compilation, an inner named subroutine or eval
           is attempting to capture an outer lexical that is not currently
           available.  This can happen for one of two reasons.  First, the
           outer lexical may be declared in an outer anonymous subroutine that
           has not yet been created.  (Remember that named subs are created at
           compile time, while anonymous subs are created at run-time.)  For
           example,

               sub { my $a; sub f { $a } }

           At the time that f is created, it can't capture the current value
           of $a, since the anonymous subroutine hasn't been created yet.
           Conversely, the following won't give a warning since the anonymous
           subroutine has by now been created and is live:

               sub { my $a; eval 'sub f { $a }' }->();

           The second situation is caused by an eval accessing a variable that
           has gone out of scope, for example,

               sub f {
                   my $a;
                   sub { eval '$a' }
               }
               f()->();

           Here, when the '$a' in the eval is being compiled, f() is not
           currently being executed, so its $a is not available for capture.

       Variable "%s" is not imported%s
           (S misc) With "use strict" in effect, you referred to a global
           variable that you apparently thought was imported from another
           module, because something else of the same name (usually a
           subroutine) is exported by that module.  It usually means you put
           the wrong funny character on the front of your variable. It is also
           possible you used an "our" variable whose scope has ended.

       Variable length lookbehind not implemented in regex m/%s/
           (F) This message no longer should be raised as of Perl 5.30.  It is
           retained in this document as a convenience for people using an
           earlier Perl version.

           In Perl 5.30 and earlier, lookbehind is allowed only for
           subexpressions whose length is fixed and known at compile time.
           For positive lookbehind, you can use the "\K" regex construct as a
           way to get the equivalent functionality.  See (?<=pattern) and \K
           in perlre.

           Starting in Perl 5.18, there are non-obvious Unicode rules under
           "/i" that can match variably, but which you might not think could.
           For example, the substring "ss" can match the single character
           LATIN SMALL LETTER SHARP S.  Here's a complete list of the current
           ones affecting ASCII characters:

              ASCII
             sequence      Matches single letter under /i
               FF          U+FB00 LATIN SMALL LIGATURE FF
               FFI         U+FB03 LATIN SMALL LIGATURE FFI
               FFL         U+FB04 LATIN SMALL LIGATURE FFL
               FI          U+FB01 LATIN SMALL LIGATURE FI
               FL          U+FB02 LATIN SMALL LIGATURE FL
               SS          U+00DF LATIN SMALL LETTER SHARP S
                           U+1E9E LATIN CAPITAL LETTER SHARP S
               ST          U+FB06 LATIN SMALL LIGATURE ST
                           U+FB05 LATIN SMALL LIGATURE LONG S T

           This list is subject to change, but is quite unlikely to.  Each
           ASCII sequence can be any combination of upper- and lowercase.

           You can avoid this by using a bracketed character class in the
           lookbehind assertion, like

            (?<![sS]t)
            (?<![fF]f[iI])

           This fools Perl into not matching the ligatures.

           Another option for Perls starting with 5.16, if you only care about
           ASCII matches, is to add the "/aa" modifier to the regex.  This
           will exclude all these non-obvious matches, thus getting rid of
           this message.  You can also say

            use if $] ge 5.016, re => '/aa';

           to apply "/aa" to all regular expressions compiled within its
           scope.  See re.

       "%s" variable %s masks earlier declaration in same %s
           (W shadow) A "my", "our" or "state" variable has been redeclared in
           the current scope or statement, effectively eliminating all access
           to the previous instance.  This is almost always a typographical
           error.  Note that the earlier variable will still exist until the
           end of the scope or until all closure references to it are
           destroyed.

       Variable syntax
           (A) You've accidentally run your script through csh instead of
           Perl.  Check the #! line, or manually feed your script into Perl
           yourself.

       Variable "%s" will not stay shared
           (W closure) An inner (nested) named subroutine is referencing a
           lexical variable defined in an outer named subroutine.

           When the inner subroutine is called, it will see the value of the
           outer subroutine's variable as it was before and during the *first*
           call to the outer subroutine; in this case, after the first call to
           the outer subroutine is complete, the inner and outer subroutines
           will no longer share a common value for the variable.  In other
           words, the variable will no longer be shared.

           This problem can usually be solved by making the inner subroutine
           anonymous, using the "sub {}" syntax.  When inner anonymous subs
           that reference variables in outer subroutines are created, they are
           automatically rebound to the current values of such variables.

       vector argument not supported with alpha versions
           (S printf) The %vd (s)printf format does not support version
           objects with alpha parts.

       Verb pattern '%s' has a mandatory argument in regex; marked by <-- HERE
       in m/%s/
           (F) You used a verb pattern that requires an argument.  Supply an
           argument or check that you are using the right verb.

       Verb pattern '%s' may not have an argument in regex; marked by <-- HERE
       in m/%s/
           (F) You used a verb pattern that is not allowed an argument.
           Remove the argument or check that you are using the right verb.

       Version control conflict marker
           (F) The parser found a line starting with "<<<<<<<", ">>>>>>>", or
           "=======".  These may be left by a version control system to mark
           conflicts after a failed merge operation.

       Version number must be a constant number
           (P) The attempt to translate a "use Module n.n LIST" statement into
           its equivalent "BEGIN" block found an internal inconsistency with
           the version number.

       Version string '%s' contains invalid data; ignoring: '%s'
           (W misc) The version string contains invalid characters at the end,
           which are being ignored.

       Warning: something's wrong
           (W) You passed warn() an empty string (the equivalent of "warn """)
           or you called it with no args and $@ was empty.

       Warning: unable to close filehandle %s properly
           (S) The implicit close() done by an open() got an error indication
           on the close().  This usually indicates your file system ran out of
           disk space.

       Warning: unable to close filehandle properly: %s
       Warning: unable to close filehandle %s properly: %s
           (S io) There were errors during the implicit close() done on a
           filehandle when its reference count reached zero while it was still
           open, e.g.:

               {
                   open my $fh, '>', $file  or die "open: '$file': $!\n";
                   print $fh $data or die "print: $!";
               } # implicit close here

           Because various errors may only be detected by close() (e.g.
           buffering could allow the "print" in this example to return true
           even when the disk is full), it is dangerous to ignore its result.
           So when it happens implicitly, perl will signal errors by warning.

           Prior to version 5.22.0, perl ignored such errors, so the common
           idiom shown above was liable to cause silent data loss.

       Warning: Use of "%s" without parentheses is ambiguous
           (S ambiguous) You wrote a unary operator followed by something that
           looks like a binary operator that could also have been interpreted
           as a term or unary operator.  For instance, if you know that the
           rand function has a default argument of 1.0, and you write

               rand + 5;

           you may THINK you wrote the same thing as

               rand() + 5;

           but in actual fact, you got

               rand(+5);

           So put in parentheses to say what you really mean.

       when is experimental
           (S experimental::smartmatch) "when" depends on smartmatch, which is
           experimental.  Additionally, it has several special cases that may
           not be immediately obvious, and their behavior may change or even
           be removed in any future release of perl.  See the explanation
           under "Experimental Details on given and when" in perlsyn.

       Wide character in %s
           (S utf8) Perl met a wide character (ordinal >255) when it wasn't
           expecting one.  This warning is by default on for I/O (like print).

           If this warning does come from I/O, the easiest way to quiet it is
           simply to add the ":utf8" layer, e.g., "binmode STDOUT, ':utf8'".
           Another way to turn off the warning is to add "no warnings 'utf8';"
           but that is often closer to cheating.  In general, you are supposed
           to explicitly mark the filehandle with an encoding, see open and
           "binmode" in perlfunc.

           If the warning comes from other than I/O, this diagnostic probably
           indicates that incorrect results are being obtained.  You should
           examine your code to determine how a wide character is getting to
           an operation that doesn't handle them.

       Wide character (U+%X) in %s
           (W locale) While in a single-byte locale (i.e., a non-UTF-8 one), a
           multi-byte character was encountered.   Perl considers this
           character to be the specified Unicode code point.  Combining
           non-UTF-8 locales and Unicode is dangerous.  Almost certainly some
           characters will have two different representations.  For example,
           in the ISO 8859-7 (Greek) locale, the code point 0xC3 represents a
           Capital Gamma.  But so also does 0x393.  This will make string
           comparisons unreliable.

           You likely need to figure out how this multi-byte character got
           mixed up with your single-byte locale (or perhaps you thought you
           had a UTF-8 locale, but Perl disagrees).

       Within []-length '%c' not allowed
           (F) The count in the (un)pack template may be replaced by
           "[TEMPLATE]" only if "TEMPLATE" always matches the same amount of
           packed bytes that can be determined from the template alone.  This
           is not possible if it contains any of the codes @, /, U, u, w or a
           *-length.  Redesign the template.

       While trying to resolve method call %s->%s() can not locate package
       "%s" yet it is mentioned in @%s::ISA (perhaps you forgot to load "%s"?)
           (W syntax) It is possible that the @ISA contains a misspelled or
           never loaded package name, which can result in perl choosing an
           unexpected parent class's method to resolve the method call. If
           this is deliberate you can do something like

             @Missing::Package::ISA = ();

           to silence the warnings, otherwise you should correct the package
           name, or ensure that the package is loaded prior to the method
           call.

       %s() with negative argument
           (S misc) Certain operations make no sense with negative arguments.
           Warning is given and the operation is not done.

       write() on closed filehandle %s
           (W closed) The filehandle you're writing to got itself closed
           sometime before now.  Check your control flow.

       %s "\x%X" does not map to Unicode
           (S utf8) When reading in different encodings, Perl tries to map
           everything into Unicode characters.  The bytes you read in are not
           legal in this encoding.  For example

               utf8 "\xE4" does not map to Unicode

           if you try to read in the a-diaereses Latin-1 as UTF-8.

       'X' outside of string
           (F) You had a (un)pack template that specified a relative position
           before the beginning of the string being (un)packed.  See "pack" in
           perlfunc.

       'x' outside of string in unpack
           (F) You had a pack template that specified a relative position
           after the end of the string being unpacked.  See "pack" in
           perlfunc.

       YOU HAVEN'T DISABLED SET-ID SCRIPTS IN THE KERNEL YET!
           (F) And you probably never will, because you probably don't have
           the sources to your kernel, and your vendor probably doesn't give a
           rip about what you want.  There is a vulnerability anywhere that
           you have a set-id script, and to close it you need to remove the
           set-id bit from the script that you're attempting to run.  To
           actually run the script set-id, your best bet is to put a set-id C
           wrapper around your script.

       You need to quote "%s"
           (W syntax) You assigned a bareword as a signal handler name.
           Unfortunately, you already have a subroutine of that name declared,
           which means that Perl 5 will try to call the subroutine when the
           assignment is executed, which is probably not what you want.  (If
           it IS what you want, put an & in front.)

       Your random numbers are not that random
           (F) When trying to initialize the random seed for hashes, Perl
           could not get any randomness out of your system.  This usually
           indicates Something Very Wrong.

       Zero length \N{} in regex; marked by <-- HERE in m/%s/
           (F) Named Unicode character escapes ("\N{...}") may return a zero-
           length sequence.  Such an escape was used in an extended character
           class, i.e.  "(?[...])", or under "use re 'strict'", which is not
           permitted.  Check that the correct escape has been used, and the
           correct charnames handler is in scope.  The <-- HERE shows
           whereabouts in the regular expression the problem was discovered.


SEE ALSO

       warnings(3), diagnostics(3).



perl v5.34.0                      2021-05-04                     PERLDIAG(1pm)

perl 5.34.0 - Generated Fri Feb 25 16:12:20 CST 2022
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