cmake-policies(7) CMake cmake-policies(7)
NAME
cmake-policies - CMake Policies Reference
INTRODUCTION
Policies in CMake are used to preserve backward compatible behavior
across multiple releases. When a new policy is introduced, newer CMake
versions will begin to warn about the backward compatible behavior. It
is possible to disable the warning by explicitly requesting the OLD, or
backward compatible behavior using the cmake_policy() command. It is
also possible to request NEW, or non-backward compatible behavior for a
policy, also avoiding the warning. Each policy can also be set to
either NEW or OLD behavior explicitly on the command line with the
CMAKE_POLICY_DEFAULT_CMP<NNNN> variable.
A policy is a deprecation mechanism and not a reliable feature toggle.
A policy should almost never be set to OLD, except to silence warnings
in an otherwise frozen or stable codebase, or temporarily as part of a
larger migration path. The OLD behavior of each policy is undesirable
and will be replaced with an error condition in a future release.
The cmake_minimum_required() command does more than report an error if
a too-old version of CMake is used to build a project. It also sets
all policies introduced in that CMake version or earlier to NEW
behavior. To manage policies without increasing the minimum required
CMake version, the if(POLICY) command may be used:
if(POLICY CMP0990)
cmake_policy(SET CMP0990 NEW)
endif()
This has the effect of using the NEW behavior with newer CMake releases
which users may be using and not issuing a compatibility warning.
The setting of a policy is confined in some cases to not propagate to
the parent scope. For example, if the files read by the include()
command or the find_package() command contain a use of cmake_policy(),
that policy setting will not affect the caller by default. Both
commands accept an optional NO_POLICY_SCOPE keyword to control this
behavior.
The CMAKE_MINIMUM_REQUIRED_VERSION variable may also be used to
determine whether to report an error on use of deprecated macros or
functions.
POLICIES INTRODUCED BY CMAKE 3.31
CMP0180
Added in version 3.31.
project() always sets <PROJECT-NAME>_* as normal variables.
In CMake 3.29 and below, the project() command set
<PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and
<PROJECT-NAME>_IS_TOP_LEVEL as cache entries, but not as normal
variables. CMake 3.30 started setting them as normal variables, but
only if they are already set as normal variables. This was needed to
preserve support for some FetchContent use cases under policy CMP0169's
NEW behavior, while also preserving behavior of nested directories that
call project() with the same project name. See release notes for
3.30.3, 3.30.4, and 3.30.5 for details.
CMake 3.31 and later prefer to always set <PROJECT-NAME>_SOURCE_DIR,
<PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL, as both
cache entries and normal variables, regardless of what cache or normal
variables already exist. This policy provides compatibility for
projects that have not been updated to expect this behavior.
The OLD behavior for this policy will only set normal variables for
<PROJECT-NAME>_SOURCE_DIR, <PROJECT-NAME>_BINARY_DIR, and
<PROJECT-NAME>_IS_TOP_LEVEL if there is already a normal variable by
that name when project() is called. The NEW behavior for this policy
will always set normal variables for <PROJECT-NAME>_SOURCE_DIR,
<PROJECT-NAME>_BINARY_DIR, and <PROJECT-NAME>_IS_TOP_LEVEL when
project() is called.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0179
Added in version 3.31.
De-duplication of static libraries on link lines keeps first
occurrence. This policy is only relevant when policy CMP0156 is set to
NEW.
Based on the linker capabilities, the static libraries can be
de-duplicated. See policy CMP0156 for more information.
CMake 3.30 and below may choose to keep, on some platforms, the last
occurrence of the static libraries rather than the fist occurrence when
they are de-duplicated.
CMake 3.31 and above prefer to keep, on all platforms, the first
occurrence of the static libraries when they are de-duplicated.
The OLD behavior for this policy is to keep, on some platforms, the
last occurrence of the static libraries when they are de-duplicated.
The NEW behavior for this policy is to keep the first occurrence of the
static libraries when they are de-duplicated, regardless of the
platform.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0178
Added in version 3.31.
Test command lines preserve empty arguments.
Empty values in the TEST_LAUNCHER and CROSSCOMPILING_EMULATOR target
properties are now preserved for tests added by the following:
o The add_test() command.
o The ExternalData_Add_Test() command from the ExternalData module.
o The gtest_add_tests() or gtest_discover_tests() commands from the
GoogleTest module.
For the gtest_add_tests() and gtest_discover_tests() commands, empty
elements in the values passed after the EXTRA_ARGS keyword are also now
preserved.
The OLD behavior of this policy silently discards empty list items from
the TEST_LAUNCHER and CROSSCOMPILING_EMULATOR target properties in the
above-mentioned cases. It also silently discards empty items from the
values given after EXTRA_ARGS for the gtest_add_tests() and
gtest_discover_tests() commands.
The NEW behavior of this policy preserves empty list items in the
TEST_LAUNCHER and CROSSCOMPILING_EMULATOR target properties, and in
values given after EXTRA_ARGS for gtest_add_tests() and
gtest_discover_tests().
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0177
Added in version 3.31.
install() DESTINATION paths are normalized.
The install() command has a number of different forms, and most of them
take a DESTINATION keyword, some in more than one place. CMake 3.30
and earlier used the value given after the DESTINATION keyword as
provided with no transformations. The install(EXPORT) form assumes the
path contains no .. or . path components when computing a path relative
to the DESTINATION, and if the project provided a path that violated
that assumption, the computed path would be incorrect.
CMake 3.31 normalizes all DESTINATION values given in any form of the
install() command, except for the INCLUDES DESTINATION of the
install(TARGETS) form. The normalization performed is the same as for
the cmake_path() command (see Normalization).
The OLD behavior of this policy performs no translation on the
DESTINATION values of any install() command. They are used exactly as
provided. If a destination path contains .. or . path components,
install(EXPORT) will use the same wrong paths as CMake 3.30 and
earlier.
The NEW behavior will normalize all DESTINATION values except for
INCLUDES DESTINATION. If a destination path contains a generator
expression, it will be wrapped in a $<PATH:CMAKE_PATH,NORMALIZE,...>
generator expression.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
will warn if it detects a path that would be different if normalized,
and uses OLD behavior. If a destination path contains a generator
expression, no such warning will be issued regardless of the value.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0176
Added in version 3.31.
execute_process() ENCODING is UTF-8 by default.
The ENCODING option is meaningful only on Windows. It specifies the
character encoding expected in the process's output on stdout and
stderr. In CMake 3.14 and below the default encoding was NONE, which
corresponds to CMake's internal UTF-8 encoding. In CMake 3.15 through
CMake 3.30 the default encoding was accidentally changed to AUTO, but
the change went unnoticed and was not documented.
CMake 3.31 and above prefer the ENCODING default to be UTF-8. This
policy provides compatibility with projects that may have been relying
on the default being AUTO.
The OLD behavior of this policy is for execute_process() to use AUTO by
default if no ENCODING is specified. The NEW behavior for this policy
is to use UTF-8 as the default ENCODING.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0175
Added in version 3.31.
add_custom_command() rejects invalid arguments.
CMake 3.30 and earlier silently ignored unsupported keywords and
missing or invalid arguments for the different forms of the
add_custom_command() command. CMake 3.31 implements more rigorous
argument checking and will flag invalid or missing arguments as errors.
The OLD behavior of this policy will accept the same invalid keywords
or arguments as CMake 3.30 and earlier. The NEW behavior will flag the
following as errors that previously went unreported:
o The OUTPUT form does not accept PRE_BUILD, PRE_LINK, or POST_BUILD
keywords.
o When the APPEND keyword is given, the OUTPUT form also does not
accept BYPRODUCTS, COMMAND_EXPAND_LISTS, DEPENDS_EXPLICIT_ONLY,
DEPFILE, JOB_POOL, JOB_SERVER_AWARE, USES_TERMINAL, or VERBATIM
keywords.
o The TARGET form requires exactly one of PRE_BUILD, PRE_LINK, or
POST_BUILD to be given. Previously, if none were given, POST_BUILD
was assumed, or if multiple keywords were given, the last one was
used.
o The TARGET form does not accept DEPENDS, DEPENDS_EXPLICIT_ONLY,
DEPFILE, IMPLICIT_DEPENDS, MAIN_DEPENDENCY, JOB_POOL, or
JOB_SERVER_AWARE keywords.
o The TARGET form now requires at least one COMMAND to be given.
o If a keyword expects a value to be given after it, but no value is
provided, that was previously treated as though the keyword was not
given at all.
o The COMMENT keyword expects exactly one value after it. If multiple
values are given, or if the COMMENT keyword is given more than once,
this is an error.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0174
Added in version 3.31.
cmake_parse_arguments(PARSE_ARGV) defines a variable for an empty
string after a single-value keyword.
One of the main reasons for using the PARSE_ARGV form of the
cmake_parse_arguments() command is to more robustly handle corner cases
related to empty values. The non-PARSE_ARGV form doesn't preserve
empty arguments, but the PARSE_ARGV form does. For each single-value
keyword given, a variable should be defined if the keyword is present,
even if it is followed by an empty string.
Prior to CMake 3.31, no variable would be defined if the value given
after a single-value keyword was an empty string. This meant the code
could not detect the difference between the keyword not being given,
and it being given but with an empty value, except by iterating over
all the arguments and checking if the keyword is present.
For the OLD behavior of this policy, cmake_parse_arguments(PARSE_ARGV)
does not define a variable for a single-value keyword followed by an
empty string, or followed by no value at all.
For the NEW behavior, cmake_parse_arguments(PARSE_ARGV) always defines
a variable for each keyword given in the arguments, even a single-value
keyword with an empty string as its value or no value at all. With the
NEW behavior, the code can robustly check if a single-value keyword was
given using just if(DEFINED <prefix>_<keyword>).
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0173
Added in version 3.31.
The CMakeFindFrameworks module is removed.
CMake's framework handling has evolved well beyond what the
CMakeFindFrameworks module supports. The module lacks any handling of
XCFrameworks, it never documented the one command it provides, and
find_library() provides superior capabilities in all respects.
The OLD behavior of this policy is for CMakeFindFrameworks to continue
to provide the undocumented cmake_find_frameworks() command. The NEW
behavior halts with a fatal error if anything tries to include the
module.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0172
Added in version 3.31.
The CPack module enables per-machine installation by default in the
CPack WIX Generator.
The CPack WIX Generator's CPACK_WIX_INSTALL_SCOPE option controls the
scope of the generated Windows Installer package. When
CPACK_WIX_VERSION is set to 4 or higher, the default scope is
perMachine. However, when using WIX 3 the default scope is NONE, and
CPack does not set any InstallScope in the package specification. The
resulting installer requires administrative privileges and installs
into the system-wide ProgramFiles directory, but the start menu entry
and uninstaller registration are created only for the current user.
The CPack module in CMake 3.30 and older does not specify any
CPACK_WIX_INSTALL_SCOPE value by default, so CPack uses no installation
scope by default with WIX 3. CMake 3.31 and newer instead prefer to
set CPACK_WIX_INSTALL_SCOPE to perMachine by default to make the
behavior consistent across all WIX versions. This policy provides
compatibility for projects that have not been updated to expect
perMachine behavior.
The OLD behavior for this policy is to not set CPACK_WIX_INSTALL_SCOPE
by default. The NEW behavior for this policy is to set
CPACK_WIX_INSTALL_SCOPE to perMachine by default.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0172 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0171
Added in version 3.31.
codegen is a reserved target name.
CMake 3.30 and earlier did not reserve codegen as a builtin target
name, leaving projects free to create their own target with that name.
CMake 3.31 and later prefer to reserve codegen as a builtin target name
to drive custom commands created with the CODEGEN option to
add_custom_command(). In order to support building the codegen target
in scripted environments, e.g., cmake --build . --target codegen, the
codegen target needs to be generated even if no custom commands use the
CODEGEN option. This policy provides compatibility for projects that
have not been updated to avoid creating a target named codegen.
The OLD behavior of this policy allows projects to create a target with
the name codegen. The NEW behavior halts with a fatal error if a
target with the name codegen is created.
This policy was introduced in CMake version 3.31. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.30
CMP0170
Added in version 3.30.
When FETCHCONTENT_FULLY_DISCONNECTED is set to true,
FetchContent_MakeAvailable() and FetchContent_Populate() enforce the
constraint that their source directory must already be populated. The
requirement has always been documented, but it was not checked or
enforced with CMake 3.29 or older. This sometimes led to hard-to-trace
errors when a project expected a dependency to have been populated, but
its population was silently skipped.
CMake 3.30 and above prefers to check and enforce the constraint. This
policy provides compatibility for situations where the user cannot
easily prevent FETCHCONTENT_FULLY_DISCONNECTED from being
inappropriately set to true.
The OLD behavior of this policy allows FETCHCONTENT_FULLY_DISCONNECTED
to be set to true even if a dependency's source directory has not been
populated. The NEW behavior halts with a fatal error if
FETCHCONTENT_FULLY_DISCONNECTED is set to true and a dependency
population would be skipped, but that dependency's source directory
doesn't exist.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0169
Added in version 3.30.
Calling FetchContent_Populate() with a single argument (the name of a
declared dependency) is deprecated.
Prior to the introduction of FetchContent_MakeAvailable(), projects
populated previously declared content (with FetchContent_Declare())
using the following pattern:
FetchContent_GetProperties(depname)
if(NOT depname_POPULATED)
FetchContent_Populate(depname)
add_subdirectory(${depname_SOURCE_DIR} ${depname_BINARY_DIR})
endif()
The above pattern does not support a number of features that have been
added to FetchContent over time. It ignores options like SYSTEM and
EXCLUDE_FROM_ALL which may be given to FetchContent_Declare(), but
can't be made known to the above project code. It also does not support
dependency providers. Projects should call
FetchContent_MakeAvailable() instead of using the above pattern.
CMake 3.30 and above prefers to reject calls to FetchContent_Populate()
with the name of a declared dependency. This policy provides
compatibility for projects that have not been updated to call
FetchContent_MakeAvailable() instead.
The OLD behavior of this policy allows FetchContent_Populate() to be
called with the name of a declared dependency. The NEW behavior halts
with a fatal error in such cases.
NOTE:
Calling FetchContent_Populate() with the full population details as
command arguments rather than just a dependency name remains fully
supported. Only the form calling FetchContent_Populate() with a
single argument (the name of a previously declared dependency) is
deprecated with this policy.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0168
Added in version 3.30.
The FetchContent module implements steps directly instead of through a
sub-build.
CMake 3.29 and below implement FetchContent as a separate sub-build.
This required configuring that separate project and using a build tool.
This approach can be very slow with some generators and operating
systems. CMake 3.30 and above prefer to implement the download,
update, and patch steps directly as part of the main project.
The NEW behavior has the following characteristics:
o No sub-build is used. All operations are implemented directly from
the main project's CMake configure step. When running in CMake script
mode, no build tool needs to be available.
o Generator expressions and GNU Make variables of the form $(SOMEVAR)
are not supported. They should not be used in any argument to
FetchContent_Declare() or FetchContent_Populate().
o All LOG_... and USES_TERMINAL_... options, the QUIET option, and the
FETCHCONTENT_QUIET variable are ignored. FetchContent output is
always part of the main project's configure output. This also means
it now respects the message logging level (see
CMAKE_MESSAGE_LOG_LEVEL and --log-level). The default message log
level should be comparable to using QUIET with the OLD policy
setting, except that warnings will now be shown.
o The PREFIX, TMP_DIR, STAMP_DIR, LOG_DIR, and DOWNLOAD_DIR options and
their associated directory properties are ignored. The FetchContent
module controls those locations internally.
o cmake --fresh will remove the stamp and script files used for
tracking and populating the dependency. This will force the
dependency's download, update, and patch steps to be re-executed. The
directory used for downloads is not affected by cmake --fresh, so any
previously downloaded files for the URL download method can still be
re-used.
The OLD behavior has the following characteristics:
o A sub-build is always used to implement the download, update, and
patch steps. A build tool must be available, even when using
FetchContent_Populate() in CMake script mode.
o Generator expressions and GNU Make variables of the form $(SOMEVAR)
can be used, although such use is almost always inappropriate. They
are evaluated in the sub-build, so they do not see any information
from the main build.
o All logging, terminal control, and directory options related to the
download, update, or patch steps are supported.
o If the QUIET option is used, or the FETCHCONTENT_QUIET variable is
set to true, warnings will not be shown in the output.
o cmake --fresh has no effect on the dependency's stamp or script
files. Previously executed steps will only re-run if details about
the dependency have changed.
There's a reasonably good chance that users can set the
CMAKE_POLICY_DEFAULT_CMP0168 variable to NEW to globally switch to the
NEW behavior while waiting for the project and its dependencies to be
updated use the NEW policy setting by default. Projects don't typically
make use of the features that the NEW behavior no longer supports, and
even those projects that do will often still work fine when those
options are ignored. Before setting this behavior globally, check
whether any FetchContent_Declare() or FetchContent_Populate() calls use
the ignored options in a way that would change observable behavior,
other than putting temporary or internally-generated files in different
locations.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0167
Added in version 3.30.
The FindBoost module is removed.
CMake 3.29 and below provide a FindBoost module, but it needs constant
updates to keep up with upstream Boost releases. Upstream Boost 1.70
and above provide a BoostConfig.cmake package configuration file.
find_package(Boost CONFIG) finds the upstream package directly, without
the find module.
CMake 3.30 and above prefer to not provide the FindBoost module so that
find_package(Boost) calls, without the CONFIG or NO_MODULE options,
find the upstream BoostConfig.cmake directly. This policy provides
compatibility for projects that have not been ported to use the
upstream Boost package.
The OLD behavior of this policy is for find_package(Boost) to load
CMake's FindBoost module. The NEW behavior is for find_package(Boost)
to search for the upstream BoostConfig.cmake.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0166
Added in version 3.30.
TARGET_PROPERTY evaluates link properties transitively over private
dependencies of static libraries.
In CMake 3.29 and below, the TARGET_PROPERTY generator expression
evaluates properties INTERFACE_LINK_OPTIONS,
INTERFACE_LINK_DIRECTORIES, and INTERFACE_LINK_DEPENDS as if they were
Transitive Compile Properties rather than Transitive Link Properties,
even when policy CMP0099 is set to NEW. Private dependencies of static
libraries, which appear in their INTERFACE_LINK_LIBRARIES guarded by
LINK_ONLY generator expressions, are not followed. This is
inconsistent with evaluation of the same target properties during
buildsystem generation.
CMake 3.30 and above prefer that TARGET_PROPERTY evaluates properties
INTERFACE_LINK_OPTIONS, INTERFACE_LINK_DIRECTORIES, and
INTERFACE_LINK_DEPENDS as Transitive Link Properties such that private
dependencies of static libraries, which appear in their
INTERFACE_LINK_LIBRARIES guarded by LINK_ONLY generator expressions,
are followed. This policy provides compatibility for projects that
have not been updated to expect the new behavior.
The OLD behavior for this policy is for TARGET_PROPERTY to evaluate
properties INTERFACE_LINK_OPTIONS, INTERFACE_LINK_DIRECTORIES, and
INTERFACE_LINK_DEPENDS as if they were Transitive Compile Properties by
not following private dependencies of static libraries. The NEW
behavior for this policy is to evaluate them as Transitive Link
Properties by following private dependencies of static libraries.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0165
Added in version 3.30.
enable_language() must not be called before project().
In CMake 3.29 and below, if a project called enable_language() before
the first call to project(), the language would be enabled but possibly
using unset details that were expected to be set. In CMake 3.30 and
above, enable_language() prefers to reject this case and stop with a
fatal error instead if it detects that project() has not yet been
called. This policy provides compatibility for projects that happened
to work when enable_language() was called before project() and have not
been updated to call these commands in the required order.
The OLD behavior for this policy is to allow enable_language() to be
called before project(). The NEW behavior for this policy is to fail
with a fatal error in such cases.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0164
Added in version 3.30.
add_library() rejects SHARED libraries when not supported by the
platform.
In CMake 3.29 and below, on platforms that do not support shared
libraries (TARGET_SUPPORTS_SHARED_LIBS is false), the add_library()
command automatically converts SHARED libraries to STATIC libraries to
help users build projects on such platforms. However, the semantics of
shared and static libraries are different enough that such automatic
conversion cannot work in general. Projects using shared libraries
need to be ported to such platforms on a case-by-case basis.
In CMake 3.30 and above, add_library() prefers to reject creation of
shared libraries on platforms that do not support them, and fail with a
fatal error message. This policy provides compatibility for projects
that happened to work with the automatic conversion to static libraries
and have not been updated with an explicit port.
The OLD behavior for this policy is to implicitly create a static
library with a developer warning. The NEW behavior for this policy is
to fail.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn about the behavior change, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0163
Added in version 3.30.
The GENERATED source file property is now visible in all directories.
In CMake 3.29 and below, the GENERATED source file property, like other
source file properties, was scoped in every directory separately.
Although policy CMP0118 allowed sources marked GENERATED in one
directory to be used in other directories without manually marking them
as GENERATED again, the GENERATED property was still not visible to
get_property() and get_source_file_property() calls.
Whether or not a source file is generated is an all-or-nothing global
property of the source: a source is either generated or it is not.
CMake 3.30 and above prefer to treat the GENERATED source file property
as globally scoped. Once it is set in one directory, it is immediately
visible to get_property() and get_source_file_property() calls in other
directories. This policy provides compatibility for projects that have
not been updated for this behavior.
The OLD behavior of this policy is for the GENERATED source file
property to be visible only in the directories in which it is set. The
NEW behavior of this policy is to allow the GENERATED source file
property to be visible in all directories once set in any directory.
Furthermore, the NEW behavior of this policy implies the NEW behavior
of policy CMP0118: the GENERATED property may be set only to boolean
values, and may not be turned off once turned on.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0162
Added in version 3.30.
Visual Studio Generators add UseDebugLibraries indicators by default.
The "Use Debug Libraries" setting in Visual Studio projects indicates
what configurations are considered debug configurations. In standalone
projects, this may affect MSBuild's default selection of MSVC runtime
library, optimization flags, runtime checks, and similar settings.
CMake typically generates all those settings explicitly based on the
project's specification, so CMake 3.29 and below do not write any
UseDebugLibraries indicators to .vcxproj files.
CMake 3.30 and above prefer to write UseDebugLibraries indicators
because they are useful for reference by both humans and tools, and may
also affect the behavior of platform-specific SDKs. The indicator for
each configuration of a target is determined as follows:
o If the target compiles sources for a known MSVC runtime library (such
as that specified by MSVC_RUNTIME_LIBRARY), then UseDebugLibraries is
true for configurations that compile for a "Debug" runtime library,
and false for others.
o Otherwise, such as in targets created by add_custom_target(),
UseDebugLibraries is true for the Debug configuration, and false for
others.
This policy provides compatibility for projects that have not been
updated to expect the indicators. The policy setting is recorded by
each target as it is created and used to determine the default behavior
for that target's .vcxproj file.
The OLD behavior for this policy is to not generate UseDebugLibraries
indicators by default. The NEW behavior for this policy is to generate
UseDebugLibraries indicators by default.
If the CMAKE_VS_USE_DEBUG_LIBRARIES variable and/or
VS_USE_DEBUG_LIBRARIES target property is set, it explicitly controls
UseDebugLibraries generation regardless of this policy.
This policy was introduced in CMake version 3.30. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.29
CMP0161
Added in version 3.29.
The CPACK_PRODUCTBUILD_DOMAINS variable defaults to true.
Before CMake 3.29, the CPACK_PRODUCTBUILD_DOMAINS variable is unset by
default. When using the CPack productbuild Generator, this disables
the use of the domains attribute in the productbuild Distribution XML,
and falls back to the auth attribute instead. These attributes control
where a productbuild package is allowed to be installed. But the auth
attribute has been deprecated by Apple, so projects should migrate to
using domains instead.
CMake 3.29 and above prefer to use a default value of true for
CPACK_PRODUCTBUILD_DOMAINS, which means domains will be used by default
unless the project explicitly sets CPACK_PRODUCTBUILD_DOMAINS to false.
This policy provides compatibility with projects that enabled the CPack
productbuild Generator, but did not explicitly set
CPACK_PRODUCTBUILD_DOMAINS.
The OLD behavior for this policy is to leave CPACK_PRODUCTBUILD_DOMAINS
unset if it hasn't been set. The NEW behavior for this policy is to
use a default value of true for CPACK_PRODUCTBUILD_DOMAINS.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
Note that a warning will only be emitted if the
CPACK_BINARY_PRODUCTBUILD variable is set to true and the project is
being built for an Apple platform.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0160
Added in version 3.29.
More read-only target properties now error when trying to set them.
The set_target_properties() and set_property() commands are intended to
error out on all read-only properties. However, CMake 3.28 and below
only did this for the following properties:
o HEADER_SETS
o INTERFACE_HEADER_SETS
o IMPORTED_GLOBAL
o MANUALLY_ADDED_DEPENDENCIES
o NAME
o TYPE
This policy enforces the read-only nature of the following target
properties:
o ALIAS_GLOBAL
o BINARY_DIR
o CXX_MODULE_SETS
o IMPORTED
o INTERFACE_CXX_MODULE_SETS
o LOCATION
o LOCATION_<CONFIG>
o SOURCE_DIR
The OLD behavior for this policy is to only error out for the
properties MANUALLY_ADDED_DEPENDENCIES, NAME, and TYPE. The NEW
behavior for this policy is to error out on all target properties that
are documented as read-only.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0159
Added in version 3.29.
file(STRINGS) with REGEX updates CMAKE_MATCH_<n>.
In CMake 3.28 and below the file(STRINGS) command's REGEX option does
not affect CMAKE_MATCH_<n> variables. CMake 3.29 and above prefer to
update the CMAKE_MATCH_<n> variables using captures from the last match
in the file, similar to the string(REGEX MATCHALL) command. This
policy provides compatibility for projects that have not been updated
to expect the behavior.
The OLD behavior for this policy is for file(STRINGS) with REGEX to not
store capture groups in CMAKE_MATCH_<n> variables. The NEW behavior is
to store the capture groups.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0158
Added in version 3.29.
add_test() honors CMAKE_CROSSCOMPILING_EMULATOR only when
cross-compiling.
In CMake 3.28 and below, add_test() unconditionally used the
CROSSCOMPILING_EMULATOR target property (initialized by the
CMAKE_CROSSCOMPILING_EMULATOR variable) to run test commands naming
executable targets. CMake 3.29 and above prefer to use the emulator
only when the CMAKE_CROSSCOMPILING variable is enabled. The
CMAKE_TEST_LAUNCHER variable may be used instead when not
cross-compiling. This policy provides compatibility for projects that
have not been updated.
The OLD behavior for this policy is for add_test() to use the
CROSSCOMPILING_EMULATOR target property unconditionally. The NEW
behavior for this policy is for add_test() to use the
CROSSCOMPILING_EMULATOR target property only when cross-compiling.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0157
Added in version 3.29.
Swift compilation mode is selected by an abstraction.
The Swift compiler can compile modules in different modes. The desired
build mode depends whether the developer is iterating and wants to
incrementally make changes, or if they are building a release for
distribution and want more optimizations applied to the resulting
binary.
CMake versions 3.26 through 3.28 build Swift binaries with whole-module
optimizations enabled when configured in a non-debug build type. For
CMake versions earlier than 3.26, the developer needs to specify the
necessary flag manually for the Ninja Generators, and cannot not
specify whole-module optimizations to the Xcode generator.
CMake versions 3.29 and above prefer to set the compilation mode using
the Swift_COMPILATION_MODE target property, which can be initialized by
the CMAKE_Swift_COMPILATION_MODE variable.
This policy provides compatibility for projects that have not been
updated. The policy setting takes effect as of the first project() or
enable_language() command that enables the Swift language.
NOTE:
Once the policy has taken effect at the top of a project, that
choice must be used throughout the tree. In projects that have
nested projects in subdirectories, be sure to convert everything
together.
The OLD behavior for this policy builds all Swift targets in
wholemodule mode for non-debug configurations. Ninja Generators
prepend the -wmo flag to the default set of Swift flags. The Xcode
generator sets the SWIFT_COMPILATION_MODE attribute to wholemodule in
the generated Xcode project file.
The NEW behavior for this policy is to apply the compilation mode
specified in the Swift_COMPILATION_MODE target property, initialized as
each target is created by the CMAKE_Swift_COMPILATION_MODE variable.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0156
Added in version 3.29.
De-duplicate libraries on link lines based on linker capabilities.
Traditional linkers maintain a set of undefined symbols during linking.
The linker processes each file in the order in which it appears on the
command line, until the set of undefined symbols becomes empty. An
object file is linked into the output object when it is encountered,
with its undefined symbols added to the set. Upon encountering an
archive file a traditional linker searches the objects contained
therein, and processes those that satisfy symbols in the unresolved
set.
Handling mutually dependent archives may be awkward when using a
traditional linker. Archive files may have to be specified multiple
times.
Some linkers (for instance Apple or Windows linkers, as well as LLVM
LLD) record all symbols found in objects and archives as they iterate
over command line arguments. When one of these linkers encounters an
undefined symbol that can be resolved by an object file contained in a
previously processed archive file, it immediately extracts and links it
into the output object.
CMake 3.28 and below may generate link lines that repeat static
libraries as a traditional linker would need, even when using a linker
that does not need it. They may also de-duplicate shared libraries by
keeping their last occurrence, which on Windows platforms can change
DLL load order.
CMake 3.29 and above prefer to apply different strategies based on
linker capabilities. So, when targeting Apple and Windows platforms,
all libraries are de-duplicated. Moreover, on Windows platforms,
libraries are de-duplicated by keeping their first occurrence, thus
respecting the project-specified order. This policy provides
compatibility with projects that have not been updated to expect the
latter behavior.
NOTE:
When this policy is set to NEW, the policy CMP0179 controls which
occurrence of the static libraries is kept when they are
de-duplicated.
The OLD behavior for this policy is to always repeat static libraries
as if using a traditional linker, and always de-duplicate shared
libraries by keeping the last occurrence of each. The NEW behavior for
this policy is to apply different strategies based on linker
capabilities.
This policy was introduced in CMake version 3.29. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.28
CMP0155
Added in version 3.28.
C++ sources in targets with at least C++20 are scanned for imports when
supported.
CMake 3.27 and below assume that C++ sources do not import modules.
CMake 3.28 and above prefer to assume that C++ sources in targets using
C++20 or higher might import modules, and must be scanned before
compiling, unless explicitly disabled. This policy provides
compatibility for projects that use C++20 or higher, without modules,
that have not been updated to turn off scanning, e.g., via the
CMAKE_CXX_SCAN_FOR_MODULES variable. See the cmake-cxxmodules(7)
manual for more details on C++ module support.
The OLD behavior for this policy is to assume that C++ 20 and newer
sources do not import modules. The NEW behavior for this policy is to
assume that C++ 20 and newer files may import modules if the compiler
understands how to scan for their dependencies, and need to be scanned.
This policy was introduced in CMake version 3.28. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0154
Added in version 3.28.
Generated files are private by default in targets using File Sets.
CMake 3.27 and below assume that any file generated as an output or
byproduct of add_custom_command() or add_custom_target() may be a
public header file meant for inclusion by dependents' source files.
This requires Ninja Generators to add conservative order-only
dependencies that prevent a target's source files from compiling before
custom commands from the target's dependencies are finished, even if
those custom commands only produce sources private to their own target.
File Sets, introduced by CMake 3.23, provide a way to express the
visibility of generated header files. CMake 3.28 and above prefer to
assume that, in targets using file sets, generated files are private to
their own target by default. Generated public headers must be
specified as members of a PUBLIC (or INTERFACE) FILE_SET, typically of
type HEADERS. With this information, Ninja Generators may omit the
above-mentioned conservative dependencies and produce more efficient
build graphs.
Additionally, if the custom command's output is a member of a file set
of type CXX_MODULES, it will additionally not be required to exist
before compiling other sources in the same target. Since these files
should not be included at compile time directly, they may not be
implicitly required to exist for other compilation rules.
This policy provides compatibility for projects using file sets in
targets with generated header files that have not been updated. Such
projects should be updated to express generated public headers in a
file set. For example:
add_custom_command(
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/foo.h
...
)
target_sources(foo
PUBLIC FILE_SET HEADERS
BASE_DIRS ${CMAKE_CURRENT_BINARY_DIR}
FILES ${CMAKE_CURRENT_BINARY_DIR}/foo.h
)
The OLD behavior for this policy is to assume generated files are
public, even in targets using file sets, and for Ninja Generators to
produce conservative build graphs. The NEW behavior for this policy is
to assume generated files are private in targets using file sets, and
for Ninja Generators to produce more efficient build graphs.
This policy was introduced in CMake version 3.28. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0153
Added in version 3.28.
The exec_program() command should not be called.
This command has long been superseded by the execute_process() command
and has been deprecated since CMake 3.0.
CMake >= 3.28 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.28. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0152
Added in version 3.28.
file(REAL_PATH) resolves symlinks before collapsing ../ components.
In CMake 3.27 and below, file(REAL_PATH) collapsed any ../ components
in a path before resolving symlinks. This produced incorrect results
when the ../ collapsed away a symlink.
The OLD behavior for this policy is to collapse ../ components before
resolving symlinks. The NEW behavior for this policy is to resolve all
symlinks before collapsing ../ components.
This policy was introduced in CMake version 3.28. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.27
CMP0151
Added in version 3.27.
AUTOMOC include directory is a system include directory by default.
Headers generated for AUTOMOC are placed in target-specific include
directories. CMake 3.26 and older added these as normal include
directories. CMake 3.27 and newer prefer to add them as system include
directories. This policy provides compatibility for projects that have
not been updated to expect this.
If the AUTOGEN_USE_SYSTEM_INCLUDE target property is set, perhaps via
the CMAKE_AUTOGEN_USE_SYSTEM_INCLUDE variable, then its value is used
regardless of the setting of this policy.
The OLD behavior for this policy is to add autogen include directory to
the target's include directories. The NEW behavior for this policy is
to add autogen include directory to the target's system include
directories.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0150
Added in version 3.27.
ExternalProject_Add() and FetchContent_Declare() commands treat
relative GIT_REPOSITORY paths as being relative to the parent project's
remote.
Earlier versions of these commands always treated relative paths in
GIT_REPOSITORY as local paths, but the base directory it was treated as
relative to was both undocumented and unintuitive. The OLD behavior
for this policy is to interpret relative paths used for GIT_REPOSITORY
as local paths relative to the following:
o The parent directory of SOURCE_DIR for ExternalProject_Add().
o FETCHCONTENT_BASE_DIR for FetchContent_Declare().
The NEW behavior is to determine the remote from the parent project and
interpret the path relative to that remote. The value of
CMAKE_CURRENT_SOURCE_DIR when ExternalProject_Add() or
FetchContent_Declare() is called determines the parent project. The
remote is selected according to the following (the first match is
used):
o If the parent project is checked out on a branch with an upstream
remote defined, use that remote.
o If only one remote is defined, use that remote.
o If multiple remotes are defined and one of them is named origin, use
origin's remote but also issue a warning.
If an appropriate remote cannot be determined from the above, a fatal
error will be raised.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns when a relative path is encountered, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0149
Added in version 3.27.
Visual Studio Generators select latest Windows SDK by default.
Visual Studio Generators select a Windows SDK version to put in the
WindowsTargetPlatformVersion setting in .vcxproj files. CMake sets the
CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION variable to the selected SDK
version.
Prior to CMake 3.27, the SDK version was always selected by the value
of the CMAKE_SYSTEM_VERSION variable. Users or toolchain files could
set that variable to one of the exact Windows SDK versions available on
the host system. Since CMAKE_SYSTEM_VERSION defaults to
CMAKE_HOST_SYSTEM_VERSION, and it is not guaranteed that a matching
Windows SDK version is available, CMake had to fall back to using the
latest Windows SDK version if no exact match was available. This
approach was problematic:
o The latest Windows SDK might or might not be selected based on
whether the host version of Windows happens to match an available SDK
version.
o An old Windows SDK version might be selected that has not been
updated for newer language standards such as C11.
CMake 3.27 and higher prefer to ignore the exact value of
CMAKE_SYSTEM_VERSION and by default select the latest SDK version
available. An exact SDK version may be specified explicitly using a
version= field in the CMAKE_GENERATOR_PLATFORM variable. See Visual
Studio Platform Selection.
This policy provides compatibility for projects, toolchain files, and
build scripts that have not been ported away from using
CMAKE_SYSTEM_VERSION to specify an exact SDK version.
NOTE:
This policy must be set before the first project() or
enable_language() command invocation at the top of the project.
That is when Visual Studio Generators select a Windows SDK.
The OLD behavior for this policy is to use the exact value of
CMAKE_SYSTEM_VERSION if possible. The NEW behavior for this policy is
to ignore it.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0148
Added in version 3.27.
The FindPythonInterp and FindPythonLibs modules are removed.
These modules have been deprecated since CMake 3.12. CMake 3.27 and
above prefer to not provide the modules. This policy provides
compatibility for projects that have not been ported away from them.
Projects using the FindPythonInterp and/or FindPythonLibs modules
should be updated to use one of their replacements:
o FindPython3
o FindPython2
o FindPython
The OLD behavior of this policy is for find_package(PythonInterp) and
find_package(PythonLibs) to load the deprecated modules. The NEW
behavior is for uses of the modules to fail as if they do not exist.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0147
Added in version 3.27.
Visual Studio Generators build custom commands in parallel.
Visual Studio 15.8 (2017) and newer support building custom commands in
parallel. CMake 3.27 and above prefer to enable this behavior by
adding a BuildInParallel setting to custom commands in .vcxproj files.
This policy provides compatibility for projects that have not been
updated to expect this, e.g., because their custom commands were
accidentally relying on serial execution by MSBuild.
The OLD behavior for this policy is to not add BuildInParallel. The
NEW behavior for this policy is to add BuildInParallel for VS 15.8 and
newer.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0146
Added in version 3.27.
The FindCUDA module is removed.
The FindCUDA module has been deprecated since CMake 3.10. CMake 3.27
and above prefer to not provide the module. This policy provides
compatibility for projects that have not been ported away from it.
Projects using the FindCUDA module should be updated to use CMake's
first-class CUDA language support. List CUDA among the languages named
in the top-level call to the project() command, or call the
enable_language() command with CUDA. Then one can add CUDA (.cu)
sources directly to targets, similar to other languages.
The OLD behavior of this policy is for find_package(CUDA) to load the
deprecated module. The NEW behavior is for uses of the module to fail
as if it does not exist.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0145
Added in version 3.27.
The Dart and FindDart modules are removed.
These modules were added very early in CMake's development to support
driving tests with a "DART" tool, but DART has not been distributed or
maintained for many years. Projects would include(Dart) to use it, and
the Dart module would run find_package(Dart) internally. Since
ctest(1) was created, the Dart module has just been a compatibility
shim that finds Dart to support some legacy functionality and then
forwards to the CTest module.
CMake 3.27 and above prefer to not provide the Dart or FindDart
modules. This policy provides compatibility for projects that have not
been ported away from them. Projects using the Dart module should be
updated to use the CTest module directly.
The OLD behavior of this policy is for include(Dart) and
find_package(Dart) to load the deprecated modules. The NEW behavior is
for uses of the modules to fail as if they do not exist.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0144
Added in version 3.27.
find_package() uses upper-case <PACKAGENAME>_ROOT variables.
In CMake 3.27 and above the find_package(<PackageName>) command now
searches prefixes specified by the upper-case <PACKAGENAME>_ROOT CMake
variable and the <PACKAGENAME>_ROOT environment variable in addition to
the case-preserved <PackageName>_ROOT and <PackageName>_ROOT variables
used since policy CMP0074. This policy provides compatibility with
projects that have not been updated to avoid using <PACKAGENAME>_ROOT
variables for other purposes.
The OLD behavior for this policy is to ignore <PACKAGENAME>_ROOT
variables if the original <PackageName> has lower-case characters. The
NEW behavior for this policy is to use <PACKAGENAME>_ROOT variables.
This policy was introduced in CMake version 3.27. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.26
CMP0143
Added in version 3.26.
USE_FOLDERS global property is treated as ON by default.
When using CMake 3.25 or earlier, USE_FOLDERS is treated as OFF by
default unless projects enable the feature. For example:
cmake_minimum_required(VERSION 3.25)
project(foobar LANGUAGES CXX)
set_property(GLOBAL PROPERTY USE_FOLDERS ON)
CMake 3.26 and later prefer to enable the feature by default.
Note that it is the policy setting at the end of the top level
CMakeLists.txt file that matters. The policy setting applies globally
to the whole project.
This policy provides compatibility with projects that have not been
updated to expect enabling of folders. Enabling folders causes
projects to appear differently in IDEs.
This policy was introduced in CMake version 3.26. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.25
CMP0142
Added in version 3.25.
The Xcode generator does not append per-config suffixes to library
search paths.
In CMake 3.24 and below, the Xcode generator preceded each entry of a
library search path with a copy of itself appended with
$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME). This was left from very
early versions of CMake in which per-config directories were not well
modeled. Such paths often do not exist, resulting in warnings from the
toolchain. CMake 3.25 and above prefer to not add such library search
paths. This policy provides compatibility for projects that may have
been accidentally relying on the old behavior.
The OLD behavior for this policy is to append
$(CONFIGURATION)$(EFFECTIVE_PLATFORM_NAME) to all library search paths.
The NEW behavior is to not modify library search paths.
This policy was introduced in CMake version 3.25. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0141
Added in version 3.25.
MSVC debug information format flags are selected by an abstraction.
Compilers targeting the MSVC ABI have flags to select the debug
information format. Debug information format selection typically varies
with build configuration.
In CMake 3.24 and below, debug information format flags are added to
the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries by CMake
automatically. This allows users to edit their cache entries to adjust
the flags. However, the presence of such default flags is problematic
for projects that want to choose a different runtime library
programmatically. In particular, it requires string editing of the
CMAKE_<LANG>_FLAGS_<CONFIG> variables with knowledge of the CMake
builtin defaults so they can be replaced.
CMake 3.25 and above prefer to leave the debug information format flags
out of the default CMAKE_<LANG>_FLAGS_<CONFIG> values and instead offer
a first-class abstraction. The CMAKE_MSVC_DEBUG_INFORMATION_FORMAT
variable and MSVC_DEBUG_INFORMATION_FORMAT target property may be set
to select the MSVC debug information format. If they are not set,
CMake enables debug information in debug configurations using the
default value $<$<CONFIG:Debug,RelWithDebInfo>:ProgramDatabase>, if
supported by the compiler, and otherwise
$<$<CONFIG:Debug,RelWithDebInfo>:Embedded>.
This policy provides compatibility with projects that have not been
updated to be aware of the abstraction. The policy setting takes
effect as of the first project() or enable_language() command that
enables a language whose compiler targets the MSVC ABI.
NOTE:
Once the policy has taken effect at the top of a project, that
choice will be used throughout the tree. In projects that have
nested projects in subdirectories, be sure to confirm if everything
is working with the selected policy behavior.
The OLD behavior for this policy is to place MSVC debug information
format flags in the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries
and ignore the CMAKE_MSVC_DEBUG_INFORMATION_FORMAT abstraction. The
NEW behavior for this policy is to not place MSVC debug information
format flags in the default cache entries and use the abstraction
instead.
This policy was introduced in CMake version 3.25. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0140
Added in version 3.25.
The return() command checks its parameters.
The OLD behavior for this policy is to ignore any parameters given to
the command. The NEW behavior is to check the validity of the
parameters.
This policy was introduced in CMake version 3.25. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.24
CMP0139
Added in version 3.24.
The if() command supports path comparisons using PATH_EQUAL operator.
The OLD behavior for this policy is to ignore the PATH_EQUAL operator.
The NEW behavior is to interpret the PATH_EQUAL operator.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0138
Added in version 3.24.
CheckIPOSupported uses flags from calling project.
The CheckIPOSupported module check_ipo_supported() command compiles a
test project to determine whether the toolchain supports
INTERPROCEDURAL_OPTIMIZATION. CMake 3.23 and below run the check with
the default values of the CMAKE_<LANG>_FLAGS and
CMAKE_<LANG>_FLAGS_<CONFIG> variables for the current environment and
toolchain settings. However, some projects may modify these flag
variables to add flags that affect availability of the toolchain's IPO
features. CMake 3.24 and above prefer to honor the calling project's
values for these variables. This policy provides compatibility for
projects that have not been updated to expect this behavior.
The OLD behavior for this policy is to ignore the calling project's
values of CMAKE_<LANG>_FLAGS and CMAKE_<LANG>_FLAGS_<CONFIG>. The NEW
behavior for this policy is to use the values of those variables as
compiler flags in the test project.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0137
Added in version 3.24.
try_compile() passes platform variables in project mode.
The try_compile() command source file signature propagates CMake
variables containing platform settings, and those specified by the
CMAKE_TRY_COMPILE_PLATFORM_VARIABLES variable, into the generated test
project. This helps the test project drive the toolchain the same way
the calling project will. In CMake 3.23 and below, the whole-project
signature does not propagate platform variables automatically. CMake
3.24 and above prefer to propagate platform variables in the
whole-project signature. This policy provides compatibility with
projects that have not been updated to expect the behavior.
The OLD behavior for this policy is to not pass any additional
variables to the whole-project signature. The NEW behavior for this
policy is to pass the same variables that the source file signature
does.
Regardless of the policy setting, the
CMAKE_TRY_COMPILE_NO_PLATFORM_VARIABLES variable may be set to suppress
passing the platform variables through either signature.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0136
Added in version 3.24.
Watcom runtime library flags are selected by an abstraction.
Compilers targeting the Watcom ABI have flags to select the Watcom
runtime library.
In CMake 3.23 and below, Watcom runtime library selection flags are
added to the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries by CMake
automatically. This allows users to edit their cache entries to adjust
the flags. However, the presence of such default flags is problematic
for projects that want to choose a different runtime library
programmatically. In particular, it requires string editing of the
CMAKE_<LANG>_FLAGS_<CONFIG> variables with knowledge of the CMake
builtin defaults so they can be replaced.
CMake 3.24 and above prefer to leave the Watcom runtime library
selection flags out of the default CMAKE_<LANG>_FLAGS_<CONFIG> values
and instead offer a first-class abstraction. The
CMAKE_WATCOM_RUNTIME_LIBRARY variable and WATCOM_RUNTIME_LIBRARY target
property may be set to select the Watcom runtime library. If they are
not set then CMake uses the default value MultiThreadedDLL on Windows
and SingleThreaded on other platforms, which is equivalent to the
original flags.
This policy provides compatibility with projects that have not been
updated to be aware of the abstraction. The policy setting takes
effect as of the first project() or enable_language() command that
enables a language whose compiler targets the Watcom ABI.
NOTE:
Once the policy has taken effect at the top of a project, that
choice must be used throughout the tree. In projects that have
nested projects in subdirectories, be sure to convert everything
together.
The OLD behavior for this policy is to place Watcom runtime library
flags in the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries and
ignore the CMAKE_WATCOM_RUNTIME_LIBRARY abstraction. The NEW behavior
for this policy is to not place Watcom runtime library flags in the
default cache entries and use the abstraction instead.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0135
Added in version 3.24.
When using the URL download method with the ExternalProject_Add() or
FetchContent_Declare() commands, CMake 3.23 and below sets the
timestamps of the extracted contents to the same as the timestamps in
the archive. When the URL changes, the new archive is downloaded and
extracted, but the timestamps of the extracted contents might not be
newer than the previous contents. Anything that depends on the
extracted contents might not be rebuilt, even though the contents may
change.
CMake 3.24 and above prefers to set the timestamps of all extracted
contents to the time of the extraction. This ensures that anything that
depends on the extracted contents will be rebuilt whenever the URL
changes.
The DOWNLOAD_EXTRACT_TIMESTAMP option to the ExternalProject_Add() and
FetchContent_Declare() commands can be used to explicitly specify how
timestamps should be handled. When DOWNLOAD_EXTRACT_TIMESTAMP is not
given, this policy controls the default behavior. The OLD behavior for
this policy is to restore the timestamps from the archive. The NEW
behavior sets the timestamps of extracted contents to the time of
extraction.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0134
Added in version 3.24.
The default registry view is TARGET for the find_file(), find_path(),
find_library(), and find_package() commands and BOTH for the
find_program() command.
The default registry views in CMake 3.23 and below are selected using
the following rules:
o if CMAKE_SIZEOF_VOID_P has value 8:
o Use view 64 for all find_* commands except find_program() command.
o Use view 64_32 for find_program() command.
o if CMAKE_SIZEOF_VOID_P has value 4 or is undefined:
o Use view 32 for all find_* commands except find_program() command.
o Use view 32_64 for find_program() command.
The OLD behavior for this policy is to use registry views 64 and 64_32
or 32_64 and 32 as default, depending of CMAKE_SIZEOF_VOID_P variable
value. The NEW behavior for this policy is to use registry views
TARGET and BOTH as default.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0133
Added in version 3.24.
The CPack module disables SLA by default in the CPack DragNDrop
Generator.
The CPack DragNDrop Generator in CMake 3.22 and below attach a Software
License Agreement (SLA) to .dmg files using the file specified by
CPACK_RESOURCE_FILE_LICENSE, if set to a non-default value. macOS 12.0
deprecated the tools used to do this, so CMake 3.23 added the
CPACK_DMG_SLA_USE_RESOURCE_FILE_LICENSE option to control the behavior.
CMake 3.23 enables that option by default for compatibility with older
versions. CMake 3.24 and above prefer to not enable the
CPACK_DMG_SLA_USE_RESOURCE_FILE_LICENSE option by default. This policy
provides compatibility with projects that have not been updated to
account for the lack of a SLA in their .dmg packages.
The OLD behavior for this policy is to enable
CPACK_DMG_SLA_USE_RESOURCE_FILE_LICENSE by default. The NEW behavior
for this policy is to not enable it by default.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0133 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0132
Added in version 3.24.
Do not set compiler environment variables on first run.
Apart from when using the Xcode generator and some Visual Studio
generators, CMake 3.23 and below will set environment variables like
CC, CXX, etc. when the corresponding language is enabled. This only
occurs on the very first time CMake is run in a build directory, and
the environment variables are only defined at configure time, not build
time. On subsequent CMake runs, these environment variables are not
set, opening up the opportunity for different behavior between the
first and subsequent CMake runs. CMake 3.24 and above prefer to not set
these environment variables when a language is enabled, even on the
first run in a build directory.
The OLD behavior for this policy sets the relevant environment variable
on the first run when a language is enabled. The NEW behavior for this
policy does not set any such environment variables.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0131
Added in version 3.24.
LINK_LIBRARIES supports the $<LINK_ONLY:...> generator expression.
CMake 3.23 and below documented the $<LINK_ONLY:...> generator
expression only for use in INTERFACE_LINK_LIBRARIES. When used in
LINK_LIBRARIES, the content guarded inside $<LINK_ONLY:...> was always
used, even when collecting non-linking usage requirements such as
INTERFACE_COMPILE_DEFINITIONS.
CMake 3.24 and above prefer to support $<LINK_ONLY:...>, when used in
LINK_LIBRARIES, by using the guarded content only for link dependencies
and not other usage requirements. This policy provides compatibility
for projects that have not been updated to account for this change.
The OLD behavior for this policy is to use LINK_LIBRARIES content
guarded by $<LINK_ONLY:...> even for non-linking usage requirements.
The NEW behavior for this policy is to use the guarded content only for
link dependencies.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0130
Added in version 3.24.
while() diagnoses condition evaluation errors.
CMake 3.23 and below accidentally tolerated errors encountered while
evaluating the condition passed to the while() command (but not the
if() command). For example, the code
set(paren "(")
while(${paren})
endwhile()
creates an unbalanced parenthesis during condition evaluation.
CMake 3.24 and above prefer to diagnose such errors. This policy
provides compatibility for projects that have not been updated to fix
their condition errors.
The OLD behavior for this policy is to ignore errors in while()
conditions. The NEW behavior for this policy is to diagnose errors in
while() conditions.
This policy was introduced in CMake version 3.24. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.23
CMP0129
Added in version 3.23.
Compiler id for MCST LCC compilers is now LCC, not GNU.
CMake 3.23 and above recognize MCST LCC compiler as a different from
GNU, with its own command line and set of capabilities. CMake now
prefers to present this to projects by setting the
CMAKE_<LANG>_COMPILER_ID variable to LCC instead of GNU. However,
existing projects may assume the compiler id for LCC is GNU as it was
in CMake versions prior to 3.23. Therefore this policy determines for
MCST LCC compiler which compiler id to report in the
CMAKE_<LANG>_COMPILER_ID variable after language <LANG> is enabled by
the project() or enable_language() command. The policy must be set
prior to the invocation of either command.
The OLD behavior for this policy is to use compiler id GNU (and set
CMAKE_<LANG>_COMPILER_VERSION to the supported GNU compiler version.)
NEW behavior for this policy is to use compiler id LCC, and set
CMAKE_<LANG>_SIMULATE_ID to GNU, and CMAKE_<LANG>_SIMULATE_VERSION to
the supported GNU compiler version.
This policy was introduced in CMake version 3.23. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0129 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.22
CMP0128
Added in version 3.22.
When this policy is set to NEW:
o <LANG>_EXTENSIONS is initialized to CMAKE_<LANG>_EXTENSIONS if set,
otherwise falling back to CMAKE_<LANG>_EXTENSIONS_DEFAULT.
o Extensions are correctly enabled/disabled if <LANG>_STANDARD is unset
or satisfied by the default.
o Standard mode-affecting flags aren't added unless necessary to
achieve the specified mode.
The OLD behavior:
o Initializes <LANG>_EXTENSIONS to CMAKE_<LANG>_EXTENSIONS if set,
otherwise falling back to ON.
o Always adds a flag if <LANG>_STANDARD is set and
<LANG>_STANDARD_REQUIRED is OFF.
o If <LANG>_STANDARD is unset:
o Doesn't disable extensions even if <LANG>_EXTENSIONS is OFF.
o Fails to enable extensions if <LANG>_EXTENSIONS is ON except for
the IAR compiler.
Code may need to be updated for the NEW behavior in the following
cases:
o If a standard mode flag previously overridden by CMake's and not used
during compiler detection now takes effect due to CMake no longer
adding one as the default detected is appropriate.
Such code should be converted to either:
o Use <LANG>_STANDARD and <LANG>_EXTENSIONS instead of manually
adding flags.
o Or ensure the manually-specified flags are used during compiler
detection.
o If extensions were disabled without <LANG>_STANDARD being set CMake
previously wouldn't actually disable extensions.
Such code should be updated to not disable extensions if they are
required.
o If extensions were enabled/disabled when <LANG>_STANDARD was
satisfied by the compiler's default CMake previously wouldn't
actually enable/disable extensions.
Such code should be updated to set the correct extensions mode.
If compiler flags affecting the standard mode are used during compiler
detection (for example in a toolchain file using
CMAKE_<LANG>_FLAGS_INIT) then they will affect the detected default
standard and extensions.
This policy was introduced in CMake version 3.22. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0128 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0127
Added in version 3.22.
cmake_dependent_option() supports full Condition Syntax.
The <depends> parameter accepts a semicolon-separated list of
conditions. CMake 3.21 and lower evaluates each condition as
if(${condition}), which does not properly handle conditions with nested
paren groups. CMake 3.22 and above instead prefer to evaluate each
condition as if(<condition>), where <condition> is re-parsed as if
literally written in a call to if(). This allows expressions like:
"A AND (B OR C)"
but requires expressions like:
"FOO MATCHES (UPPER|lower)"
to be re-written as:
"FOO MATCHES \"(UPPER|lower)\""
Policy CMP0127 provides compatibility for projects that have not been
updated to expect the new behavior.
This policy was introduced in CMake version 3.22. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.21
CMP0126
Added in version 3.21.
When this policy is set to NEW, the set(CACHE) command does not remove
any normal variable of the same name from the current scope. The OLD
behavior removes any normal variable of the same name from the current
scope in the following situations:
o No cache variable of that name existed previously.
o A cache variable of that name existed previously, but it had no type.
This can occur when the variable was set on the command line using a
form like cmake -DMYVAR=blah instead of cmake -DMYVAR:STRING=blah.
o The FORCE or INTERNAL keywords were used when setting the cache
variable.
Note that the NEW behavior has an important difference to the similar
NEW behavior of policy CMP0077. The set(CACHE) command always sets the
cache variable if it did not exist previously, regardless of the
CMP0126 policy setting. The option() command will not set the cache
variable if a non-cache variable of the same name already exists and
CMP0077 is set to NEW.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0126 variable to
control the warning.
The CMAKE_POLICY_DEFAULT_CMP0126 variable may be used to set the policy
for a third-party project in a subdirectory without modifying it.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0125
Added in version 3.21.
The find_file(), find_path(), find_library() and find_program()
commands cache their result in the variable specified by their first
argument. Prior to CMake 3.21, if a cache variable of that name
already existed before the call but the cache variable had no type, any
non-cache variable of the same name would be discarded and the cache
variable was always used (see also CMP0126 for a different but similar
behavior). This contradicts the convention that a non-cache variable
should take precedence over a cache variable of the same name. Such a
situation can arise if a user sets a cache variable on the command line
without specifying a type, such as cmake -DMYVAR=blah ... instead of
cmake -DMYVAR:FILEPATH=blah.
Related to the above, if a cache variable of the specified name already
exists and it does have a type, the various find_...() commands would
return that value unchanged. In particular, if it contained a relative
path, it would not be converted to an absolute path in this situation.
When policy CMP0125 is set to OLD or is unset, the behavior is as
described above. When it is set to NEW, the behavior is as follows:
o If a non-cache variable of the specified name exists when the
find_...() command is called, its value will be used regardless of
whether a cache variable of the same name already exists or not. A
cache variable will not be created in this case if no such cache
variable existed before. If a cache variable of the specified name
did already exist, the cache will be updated to match the non-cache
variable.
o The various find...() commands will always provide an absolute path
in the result variable, except where a relative path provided by a
cache or non-cache variable cannot be resolved to an existing path.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0124
Added in version 3.21.
foreach() loop variables are only available in the loop scope.
CMake 3.20 and below always leave the loop variable set at the end of
the loop, either to the value it had before the loop, if any, or to the
empty string. CMake 3.21 and above prefer to leave the loop variable
in the state it had before the loop started, either set or unset. This
policy provides compatibility for projects that expect the loop
variable to always be left set.
The OLD behavior for this policy is to set the loop variable at the end
of the loop, either to its original value, or to an empty value. The
NEW behavior for this policy is to restore the loop variable to the
state it had before the loop started, either set or unset.
For example:
set(items a b c)
set(var1 "value")
unset(var2)
foreach(var1 IN LISTS items)
endforeach()
foreach(var2 IN LISTS items)
endforeach()
if(DEFINED var1)
message("var1: ${var1}")
endif()
if(DEFINED var2)
message("var2: ${var2}")
endif()
Under the OLD behavior, this code prints var1: value and var2:. Under
the NEW behavior, this code prints only var1: value.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0123
Added in version 3.21.
ARMClang cpu/arch compile and link flags must be set explicitly.
CMake 3.20 and lower automatically maps the CMAKE_SYSTEM_PROCESSOR
variable and an undocumented CMAKE_SYSTEM_ARCH to compile and link
options for ARMClang. For example, the -mcpu=cortex-m33 flag is added
when CMAKE_SYSTEM_PROCESSOR equals cortex-m33. CMake requires projects
to set either variable or it raises a fatal error. However, the
project may need to additionally specify CPU features using e.g.
-mcpu=cortex-m33+nodsp, conflicting with the -mcpu=cortex-m33 added by
CMake. This results in either link errors or unusable binaries.
CMake 3.21 and above prefer instead to not add any cpu/arch compile and
link flags automatically. Instead, projects must specify them
explicitly. This policy provides compatibility for projects that have
not been updated.
The OLD behavior of this policy requires projects that use ARMClang to
set either CMAKE_SYSTEM_PROCESSOR or CMAKE_SYSTEM_ARCH and it
automatically adds a compile option -mcpu= or -march= and a link option
--cpu= based on those variables. The NEW behavior does not add compile
or link options, and projects are responsible for setting correct
options.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0122
Added in version 3.21.
UseSWIG use library name conventions for CSharp language.
Starting with CMake 3.21, UseSWIG generates now a library using default
naming conventions. This policy provides compatibility with projects
that expect the legacy behavior.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0121
Added in version 3.21.
The list() command now detects invalid indices.
Prior to CMake version 3.21, the list() command's GET, INSERT, SUBLIST,
and REMOVE_AT subcommands did not detect invalid index arguments.
The OLD behavior of this policy is for invalid indices to be treated as
their integer value (if any) at the start of the string. For example,
2good4you is a 2 and not_an_integer is a 0. The NEW behavior is for
invalid indices to trigger an error.
This policy was introduced in CMake version 3.21. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.20
CMP0120
Added in version 3.20.
The WriteCompilerDetectionHeader module is removed.
CMake versions 3.1 through 3.19 provide this module to generate a C++
compatibility layer by re-using information from CMake's table of
preprocessor checks for cmake-compile-features(7). However:
o Those granular features have been superseded by meta-features for
Requiring Language Standards such as cxx_std_11. Therefore no new
granular feature checks will be added and projects will need to use
other means to conditionally use new C++ features.
o The module exposes some of CMake's implementation details directly to
C++ translation units.
o The module's approach effectively provides a header file with CMake,
thus tying the version of the header to the version of CMake. Many
projects found that the WriteCompilerDetectionHeader was best used by
manually generating its header locally with a recent version of CMake
and then bundling it with the project source so that it could be used
with older CMake versions.
For reasons including the above, CMake 3.20 and above prefer to not
provide the WriteCompilerDetectionHeader module. This policy provides
compatibility for projects that have not been ported away from it.
Projects using the module should be updated to stop using it.
Alternatives include:
o Bundle a copy of the generated header in the project's source.
o Use a third-party alternative, such as the CC0-licensed Hedley.
o Drop support for compilers too old to provide the features natively.
The OLD behavior of this policy is for inclusion of the deprecated
WriteCompilerDetectionHeader module to work. The NEW behavior is for
inclusion of the module to fail as if it does not exist.
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0119
Added in version 3.20.
LANGUAGE source file property explicitly compiles as specified
language.
The LANGUAGE source file property is documented to mean that the source
file is written in the specified language. In CMake 3.19 and below,
setting this property causes CMake to compile the source file using the
compiler for the specified language. However, it only passes an
explicit flag to tell the compiler to treat the source as the specified
language for MSVC-like, XL, and Embarcadero compilers for the CXX
language. CMake 3.20 and above prefer to also explicitly tell the
compiler to use the specified language using a flag such as -x c on all
compilers for which such flags are known.
This policy provides compatibility for projects that have not been
updated to expect this behavior. For example, some projects were
setting the LANGUAGE property to C on assembly-language .S source files
in order to compile them using the C compiler. Such projects should be
updated to use enable_language(ASM), for which CMake will often choose
the C compiler as the assembler on relevant platforms anyway.
The OLD behavior for this policy is to interpret the LANGUAGE <LANG>
property using its undocumented meaning to "use the <LANG> compiler".
The NEW behavior for this policy is to interpret the LANGUAGE <LANG>
property using its documented meaning to "compile as a <LANG> source".
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0118
Added in version 3.20.
GENERATED sources may be used across directories without manual
marking.
In CMake 3.19 and below, the GENERATED source file property, like other
source file properties, was scoped in every directory separately. If a
source file was generated in one directory, projects had to manually
set the GENERATED property in another directory in order to use the
file.
Whether or not a source file is generated is an all-or-nothing global
property of the source: a source is either generated or it is not.
CMake 3.20 and above prefer to allow source files generated in one
directory to be used in other directories without manually marking them
as GENERATED. Additionally, the GENERATED property may now be set only
to boolean values, and may not be turned off once turned on. This
policy provides compatibility for projects that have not been updated
for this behavior.
The OLD behavior of this policy is to allow generated files to be used
only in directories in which their GENERATED property has been turned
on. The NEW behavior of this policy is to allow generated files to be
used in other directories without explicitly turning on the GENERATED
property for those directories.
Added in version 3.30: Policy CMP0163 additionally makes the GENERATED
source file property visible to get_property() and
get_source_file_property() calls in other directories.
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns about setting the GENERATED property to a non-boolean value, and
uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0117
Added in version 3.20.
MSVC RTTI flag /GR is not added to CMAKE_CXX_FLAGS by default.
When using MSVC-like compilers in CMake 3.19 and below, the RTTI flag
/GR is added to CMAKE_CXX_FLAGS by default. This behavior is left from
support for MSVC versions from Visual Studio 2003 and below that did
not enable RTTI by default. It is no longer necessary. Furthermore,
it is problematic for projects that want to change to /GR-
programmatically. In particular, it requires string editing of the
CMAKE_CXX_FLAGS variable with knowledge of the CMake builtin default so
it can be replaced.
CMake 3.20 and above prefer to leave out /GR from the value of
CMAKE_CXX_FLAGS by default.
This policy provides compatibility with projects that have not been
updated to expect the lack of the /GR flag. The policy setting takes
effect as of the first project() or enable_language() command that
initializes CMAKE_CXX_FLAGS.
NOTE:
Once the policy has taken effect at the top of a project for a given
language, that choice must be used throughout the tree for that
language. In projects that have nested projects in subdirectories,
be sure to convert everything together.
The OLD behavior for this policy is to place the MSVC /GR flag in the
default CMAKE_CXX_FLAGS cache entry. The NEW behavior for this policy
is to not place the MSVC /GR flag in the default cache entry.
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0116
Added in version 3.20.
Ninja generators transform DEPFILE s from add_custom_command().
In CMake 3.19 and below, files given to the DEPFILE argument of
add_custom_command() were passed directly to Ninja's depfile variable
without any path resolution. This meant that if add_custom_command()
was called from a subdirectory (created by add_subdirectory()), the
DEPFILE argument would have to be either an absolute path or a path
relative to CMAKE_BINARY_DIR, rather than CMAKE_CURRENT_BINARY_DIR. In
addition, no transformation was done on the file listed in DEPFILE,
which meant that the paths within the DEPFILE had the same
restrictions.
Starting with CMake 3.20, the DEPFILE argument is relative to
CMAKE_CURRENT_BINARY_DIR (unless it is absolute), and the paths in the
DEPFILE are also relative to CMAKE_CURRENT_BINARY_DIR. CMake
automatically transforms the paths in the DEPFILE (unless they are
absolute) after the custom command is run. The file listed in DEPFILE
is not modified in any way. Instead, CMake writes the transformation to
its own internal file, and passes this internal file to Ninja's depfile
variable. This transformation happens regardless of whether or not
DEPFILE is relative, and regardless of whether or not
add_custom_command() is called from a subdirectory.
The OLD behavior for this policy is to pass the DEPFILE to Ninja
unaltered. The NEW behavior for this policy is to transform the DEPFILE
after running the custom command. The status of CMP0116 is recorded at
the time of the custom command's creation, and you can have custom
commands in the same directory with different values for CMP0116 by
setting the policy before each custom command.
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default (unless DEPFILE is used in a subdirectory),
and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0116 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0115
Added in version 3.20.
Source file extensions must be explicit.
In CMake 3.19 and below, if a source file could not be found by the
name specified, it would append a list of known extensions to the name
to see if the file with the extension could be found. For example, this
would allow the user to run:
add_executable(exe main)
and put main.c in the executable without specifying the extension.
Starting in CMake 3.20, CMake prefers all source files to have their
extensions explicitly listed:
add_executable(exe main.c)
The OLD behavior for this policy is to implicitly append known
extensions to source files if they can't be found. The NEW behavior of
this policy is to not append known extensions and require them to be
explicit.
This policy was introduced in CMake version 3.20. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.19
CMP0114
Added in version 3.19.
ExternalProject step targets fully adopt their steps.
The ExternalProject_Add() STEP_TARGETS option, and the
ExternalProject_Add_StepTargets() function, can be used to create build
targets for individual steps of an external project.
In CMake 3.18 and below, step targets have some limitations:
o Step targets always depend on targets named by the
ExternalProject_Add() DEPENDS option even though not all steps need
them. In order to allow step targets to be created without those
dependencies, the ExternalProject_Add() INDEPENDENT_STEP_TARGETS
option or the ExternalProject_Add_StepTargets() NO_DEPENDS option may
be used. However, adding such "independent" step targets makes sense
only for specific steps such as download, update, and patch because
they do not need any of the external project's build dependencies.
Furthermore, it does not make sense to create independent step
targets for steps that depend on non-independent steps. Such rules
are not enforced, and projects that do not follow them can generate
build systems with confusing and generator-specific behavior.
o Step targets hold copies of the custom commands implementing their
steps that are separate from the copies in the primary target created
by ExternalProject_Add(), and the primary target does not depend on
the step targets. In parallel builds that drive the primary target
and step targets concurrently, multiple copies of the steps' commands
may run concurrently and race each other.
Also, prior to policy CMP0113, the step targets generated by Makefile
Generators also contain all the custom commands on which their step
depends. This can lead to repeated execution of those steps even in
serial builds.
In CMake 3.19 and above, the ExternalProject module prefers a revised
design to address these problems:
o Each step is classified as "independent" if it does not depend on
other targets named by the ExternalProject_Add() DEPENDS. The
predefined steps are automatically classified by default:
o The download, update, and patch steps are independent.
o The configure, build, test, and install steps are not.
For custom steps, the ExternalProject_Add_Step() command provides an
INDEPENDENT option to mark them as independent. It is an error to
mark a step as independent if it depends on other steps that are not.
Note that this use of the term "independent" refers only to
independence from external targets and is orthogonal to a step's
dependencies on other steps.
o Step targets created by the ExternalProject_Add() STEP_TARGETS option
or the ExternalProject_Add_Step() function are now independent if and
only if their steps are marked as independent. The
ExternalProject_Add() INDEPENDENT_STEP_TARGETS option and
ExternalProject_Add_StepTargets() NO_DEPENDS option are no longer
allowed.
o Step targets, when created, are fully responsible for holding the
custom commands implementing their steps. The primary target created
by ExternalProject_Add() depends on the step targets, and the step
targets depend on each other. The target-level dependencies match
the file-level dependencies used by the custom commands for each
step.
When the ExternalProject_Add() UPDATE_DISCONNECTED or
TEST_EXCLUDE_FROM_MAIN option is used, or the
ExternalProject_Add_Step() EXCLUDE_FROM_MAIN option is used for a
custom step, some step targets may be created automatically. These
are needed to hold the steps commonly depended upon by the primary
target and the disconnected step targets.
Policy CMP0114 provides compatibility for projects that have not been
updated to expect the new behavior. The OLD behavior for this policy
is to use the above-documented behavior from 3.18 and below. The NEW
behavior for this policy is to use the above-documented behavior
preferred by 3.19 and above.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0113
Added in version 3.19.
Makefile Generators do not repeat custom commands from target
dependencies.
Consider a chain of custom commands split across two dependent targets:
add_custom_command(OUTPUT output-not-created
COMMAND ... DEPENDS ...)
set_property(SOURCE output-not-created PROPERTY SYMBOLIC 1)
add_custom_command(OUTPUT output-created
COMMAND ... DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/output-not-created)
add_custom_target(first DEPENDS output-not-created)
add_custom_target(second DEPENDS output-created)
add_dependencies(second first)
In CMake 3.18 and lower, the Makefile generators put a copy of both
custom commands in the Makefile for target second even though its
dependency on target first ensures that the first custom command runs
before the second. Running make second would cause the first custom
command to run once in the first target and then again in the second
target.
CMake 3.19 and above prefer to not duplicate custom commands in a
target that are already generated in other targets on which the target
depends (directly or indirectly). This policy provides compatibility
for projects that have not been updated to expect the new behavior. In
particular, projects that relied on the duplicate execution or that did
not properly set the SYMBOLIC source file property may be affected.
The OLD behavior for this policy is to duplicate custom commands in
dependent targets. The NEW behavior of this policy is to not duplicate
custom commands in dependent targets.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0112
Added in version 3.19.
Target file component generator expressions do not add target
dependencies.
The following target-based generator expressions that query for
directory or file name components no longer add a dependency on the
evaluated target.
o TARGET_FILE_NAME
o TARGET_FILE_DIR
o TARGET_LINKER_FILE_BASE_NAME
o TARGET_LINKER_FILE_NAME
o TARGET_LINKER_FILE_DIR
o TARGET_SONAME_FILE_NAME
o TARGET_SONAME_FILE_DIR
o TARGET_PDB_FILE_NAME
o TARGET_PDB_FILE_DIR
o TARGET_BUNDLE_DIR
o TARGET_BUNDLE_DIR_NAME
o TARGET_BUNDLE_CONTENT_DIR
In CMake 3.18 and lower a dependency on the evaluated target of the
above generator expressions would always be added. CMake 3.19 and
above prefer to not add this dependency. This policy provides
compatibility for projects that have not been updated to expect the new
behavior. The policy setting is recorded on each target when it is
created, and decides whether generator expressions referencing that
target imply a dependency on it.
The OLD behavior for this policy is to add a dependency on the
evaluated target for the above generator expressions. The NEW behavior
of this policy is to not add a dependency on the evaluated target for
the above generator expressions.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0112 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0111
Added in version 3.19.
An imported target missing its location property fails during
generation.
Imported Targets for library files and executables require that their
location on disk is specified in a target property such as
IMPORTED_LOCATION, IMPORTED_IMPLIB, or a per-configuration equivalent.
If a needed location property is not set, CMake 3.18 and below generate
the string <TARGET_NAME>-NOTFOUND in its place, which results in
failures of the corresponding rules at build time. CMake 3.19 and
above prefer instead to raise an error during generation. This policy
provides compatibility for projects that have not been updated to
expect the new behavior.
The OLD behavior of this policy is to generate the location of an
imported unknown, static or shared library target as
<TARGET_NAME>-NOTFOUND if not set. The NEW behavior is to raise an
error.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0110
Added in version 3.19.
add_test() supports arbitrary characters in test names.
add_test() can now (officially) create tests with whitespace and other
special characters in its name. Before CMake version 3.19 that was not
allowed, however, it was possible to work around this limitation by
explicitly putting escaped quotes around the test's name in the
add_test command.
Although never officially supported several projects in the wild found
and implemented this workaround. However, the new change which
officially allows the add_test command to support whitespace and other
special characters in test names now breaks that workaround. In order
for these projects to work smoothly with newer CMake versions, this
policy was introduced.
The OLD behavior of this policy is to still prevent add_test from
handling whitespace and special characters properly (if not using the
mentioned workaround). The NEW behavior on the other hand allows names
with whitespace and special characters for tests created by add_test.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0109
Added in version 3.19.
find_program() requires permission to execute but not to read.
In CMake 3.18 and below, the find_program() command on UNIX would find
files that are readable without requiring execute permission, and would
not find files that are executable without read permission. In CMake
3.19 and above, find_program now prefers to require execute permission
but not read permission. This policy provides compatibility with
projects that have not been updated to expect the new behavior.
The OLD behavior for this policy is for find_program to require read
permission but not execute permission. The NEW behavior for this
policy is for find_program to require execute permission but not read
permission.
This policy was introduced in CMake version 3.19. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.18
CMP0108
Added in version 3.18.
A target is not allowed to link to itself even through an ALIAS target.
In CMake 3.17 and below, a target can link to a target aliased to
itself.
The OLD behavior for this policy is to allow a target to link to a
target aliased to itself.
The NEW behavior of this policy is to prevent a target to link to
itself through an ALIAS target.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0107
Added in version 3.18.
It is not allowed to create an ALIAS target with the same name as an
another target.
In CMake 3.17 and below, an ALIAS target can overwrite silently an
existing target with the same name.
The OLD behavior for this policy is to allow target overwrite.
The NEW behavior of this policy is to prevent target overwriting.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0106
Added in version 3.18.
The Documentation module is removed.
The Documentation was added as a support mechanism for the VTK project
and was tuned for that project. Instead of CMake providing this module
with (now old) VTK patterns for cache variables and required packages,
the module is now deprecated by CMake itself.
The OLD behavior of this policy is for Documentation to add cache
variables and find VTK documentation dependent packages. The NEW
behavior is to act as an empty module.
This policy was introduced in CMake version 3.18. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0105
Added in version 3.18.
LINK_OPTIONS and INTERFACE_LINK_OPTIONS target properties are now used
for the device link step.
In CMake 3.17 and below, link options are not used by the device link
step.
The OLD behavior for this policy is to ignore the link options during
the device link step.
The NEW behavior of this policy is to use the link options during the
device link step.
This policy was introduced in CMake version 3.18. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0104
Added in version 3.18.
Initialize CMAKE_CUDA_ARCHITECTURES when CMAKE_CUDA_COMPILER_ID is
NVIDIA. Raise an error if CUDA_ARCHITECTURES is empty.
CMAKE_CUDA_ARCHITECTURES introduced in CMake 3.18 is used to initialize
CUDA_ARCHITECTURES, which passes correct code generation flags to the
CUDA compiler.
Previous to this users had to manually specify the code generation
flags. This policy is for backwards compatibility with manually
specifying code generation flags.
The OLD behavior for this policy is to not initialize
CMAKE_CUDA_ARCHITECTURES when CMAKE_CUDA_COMPILER_ID is NVIDIA. Empty
CUDA_ARCHITECTURES is allowed.
The NEW behavior of this policy is to initialize
CMAKE_CUDA_ARCHITECTURES when CMAKE_CUDA_COMPILER_ID is NVIDIA and
raise an error if CUDA_ARCHITECTURES is empty during generation.
If CUDA_ARCHITECTURES is set to a false value no architectures flags
are passed to the compiler. This is intended to support packagers and
the rare cases where full control over the passed flags is required.
This policy was introduced in CMake version 3.18. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
Examples
set_target_properties(tgt PROPERTIES CUDA_ARCHITECTURES "35;50;72")
Generates code for real and virtual architectures 30, 50 and 72.
set_property(TARGET tgt PROPERTY CUDA_ARCHITECTURES 70-real 72-virtual)
Generates code for real architecture 70 and virtual architecture 72.
set_property(TARGET tgt PROPERTY CUDA_ARCHITECTURES OFF)
CMake will not pass any architecture flags to the compiler.
CMP0103
Added in version 3.18.
Multiple calls to export() command with same FILE without APPEND is no
longer allowed.
In CMake 3.17 and below, multiple calls to export() command with the
same FILE without APPEND are accepted silently but only the last
occurrence is taken into account during the generation.
The OLD behavior for this policy is to ignore the multiple occurrences
of export() command except the last one.
The NEW behavior of this policy is to raise an error on second call to
export() command with same FILE without APPEND.
This policy was introduced in CMake version 3.18. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.17
CMP0102
Added in version 3.17.
The mark_as_advanced() command no longer creates a cache entry if one
does not already exist.
In CMake 3.16 and below, if a variable was not defined at all or just
defined locally, the mark_as_advanced() command would create a new
cache entry with an UNINITIALIZED type and no value. When a find_path()
(or other similar find_ command) would next run, it would find this
undefined cache entry and set it up with an empty string value. This
process would end up deleting the local variable in the process (due to
the way the cache works), effectively clearing any stored find_ results
that were only available in the local scope.
The OLD behavior for this policy is to create the empty cache
definition. The NEW behavior of this policy is to ignore variables
which do not already exist in the cache.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0102 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0101
Added in version 3.17.
target_compile_options() now always honors the BEFORE keyword.
In CMake 3.16 and below, the target_compile_options() command ignores
the BEFORE keyword when inserting items into the COMPILE_OPTIONS target
property (PRIVATE and PUBLIC items). CMake 3.17 and later honors the
BEFORE keyword in all cases. This policy provides compatibility for
projects that have not been updated to expect the new behavior.
The behavior of inserting items into the INTERFACE_COMPILE_OPTIONS
target property (PUBLIC and INTERFACE items) is not affected by this
policy. The BEFORE keyword has always been honored when adding items
to INTERFACE_COMPILE_OPTIONS.
The OLD behavior for this policy is to not honor the BEFORE keyword
when inserting into the COMPILE_OPTIONS property. The NEW behavior for
this policy is to honor the BEFORE keyword in all cases.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0100
Added in version 3.17.
Let AUTOMOC and AUTOUIC process header files that end with a .hh
extension.
Since version 3.17, CMake processes header files that end with a .hh
extension in AUTOMOC and AUTOUIC. In earlier CMake versions, these
header files were ignored by AUTOMOC and AUTOUIC.
This policy affects how header files that end with a .hh extension get
treated in AUTOMOC and AUTOUIC.
The OLD behavior for this policy is to ignore .hh header files in
AUTOMOC and AUTOUIC.
The NEW behavior for this policy is to process .hh header files in
AUTOMOC and AUTOUIC just like other header files.
NOTE:
To silence the CMP0100 warning source files can be excluded from
AUTOMOC and AUTOUIC processing by setting the source file properties
SKIP_AUTOMOC, SKIP_AUTOUIC or SKIP_AUTOGEN.
# Source skip example:
set_property(SOURCE /path/to/file1.hh PROPERTY SKIP_AUTOMOC ON)
set_property(SOURCE /path/to/file2.hh PROPERTY SKIP_AUTOUIC ON)
set_property(SOURCE /path/to/file3.hh PROPERTY SKIP_AUTOGEN ON)
This policy was introduced in CMake version 3.17.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0099
Added in version 3.17.
Link properties are transitive over private dependencies of static
libraries.
In CMake 3.16 and below, evaluation of target properties
INTERFACE_LINK_OPTIONS, INTERFACE_LINK_DIRECTORIES, and
INTERFACE_LINK_DEPENDS during buildsystem generation does not follow
private dependencies of static libraries, which appear in their
INTERFACE_LINK_LIBRARIES guarded by LINK_ONLY generator expressions.
Only the libraries themselves are propagated to link the dependent
binary.
CMake 3.17 and later prefer to propagate all interface link properties.
This policy provides compatibility for projects that have not been
updated to expect the new behavior.
The OLD behavior for this policy is to not propagate interface link
properties. The NEW behavior of this policy is to propagate interface
link properties.
Added in version 3.30: Policy CMP0166 makes TARGET_PROPERTY evaluation
of these three transitive link properties follow private dependencies
of static libraries too.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0098
Added in version 3.17.
FindFLEX runs flex in directory CMAKE_CURRENT_BINARY_DIR when
executing.
The module provides a FLEX_TARGET macro which generates FLEX output.
In CMake 3.16 and below the macro would generate a custom command that
runs flex in the current source directory. CMake 3.17 and later prefer
to run it in the build directory and use CMAKE_CURRENT_BINARY_DIR as
the WORKING_DIRECTORY of its add_custom_command() invocation. This
ensures that any implicitly generated file is written relative to the
build tree rather than the source tree, unless the generated file is
provided as absolute path.
This policy provides compatibility for projects that have not been
updated to expect the new behavior.
The OLD behavior for this policy is for FLEX_TARGET to use the current
source directory for the WORKING_DIRECTORY and where to generate
implicit files. The NEW behavior of this policy is to use the current
binary directory for the WORKING_DIRECTORY relative to which implicit
files are generated unless provided as absolute path.
This policy was introduced in CMake version 3.17. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.16
CMP0097
Added in version 3.16.
ExternalProject_Add() with GIT_SUBMODULES "" initializes no submodules.
The commands provide a GIT_SUBMODULES option which controls what
submodules to initialize and update. Starting with CMake 3.16,
explicitly setting GIT_SUBMODULES to an empty string means no
submodules will be initialized or updated.
This policy provides compatibility for projects that have not been
updated to expect the new behavior.
The OLD behavior for this policy is for GIT_SUBMODULES when set to an
empty string to initialize and update all git submodules. The NEW
behavior for this policy is for GIT_SUBMODULES when set to an empty
string to initialize and update no git submodules.
This policy was introduced in CMake version 3.16. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
This policy also applies to FetchContent_Declare(), which uses the
same download and update features as ExternalProject_Add().
However, due to an implementation deficiency present since the
policy was first introduced, CMake 3.16 and later always uses the
NEW behavior for FetchContent_Declare(), regardless of the policy
setting. Formally, this forcing of NEW behavior for
FetchContent_Declare() will continue to apply in future CMake
releases.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0096
Added in version 3.16.
The project() command preserves leading zeros in version components.
When a VERSION <major>[.<minor>[.<patch>[.<tweak>]]]] argument is given
to the project() command, it stores the version string in the
PROJECT_VERSION variable and stores individual integer version
components in PROJECT_VERSION_{MAJOR,MINOR,PATCH,TWEAK} variables (see
policy CMP0048). CMake 3.15 and below dropped leading zeros from each
component. CMake 3.16 and higher prefer to preserve leading zeros.
This policy provides compatibility for projects that have not been
updated to expect the new behavior.
The OLD behavior of this policy drops leading zeros in all components,
e.g. such that version 1.07.06 becomes 1.7.6. The NEW behavior of
this policy preserves the leading zeros in all components, such that
version 1.07.06 remains unchanged.
This policy was introduced in CMake version 3.16. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0095
Added in version 3.16.
RPATH entries are properly escaped in the intermediary CMake install
script.
In CMake 3.15 and earlier, RPATH entries set via CMAKE_INSTALL_RPATH or
via INSTALL_RPATH have not been escaped before being inserted into the
cmake_install.cmake script. Dynamic linkers on ELF-based systems (e.g.
Linux and FreeBSD) allow certain keywords in RPATH entries, such as
${ORIGIN} (More details are available in the ld.so man pages on those
systems). The syntax of these keywords can match CMake's variable
syntax. In order to not be substituted (usually to an empty string)
already by the intermediary cmake_install.cmake script, the user had to
double-escape such RPATH keywords, e.g. set(CMAKE_INSTALL_RPATH
"\\\${ORIGIN}/../lib"). Since the intermediary cmake_install.cmake
script is an implementation detail of CMake, CMake 3.16 and later will
make sure RPATH entries are inserted literally by escaping any
coincidental CMake syntax.
The OLD behavior of this policy is to not escape RPATH entries in the
intermediary cmake_install.cmake script. The NEW behavior is to
properly escape coincidental CMake syntax in RPATH entries when
generating the intermediary cmake_install.cmake script.
This policy was introduced in CMake version 3.16. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns when it detects use of CMake-like syntax, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.15
CMP0094
Added in version 3.15.
Modules FindPython3, FindPython2 and FindPython use LOCATION for lookup
strategy.
Starting with CMake 3.15, Modules FindPython3, FindPython2 and
FindPython set value LOCATION for, respectively, variables
Python3_FIND_STRATEGY, Python2_FIND_STRATEGY and Python_FIND_STRATEGY.
This policy provides compatibility with projects that expect the legacy
behavior.
The OLD behavior for this policy set value VERSION for variables
Python3_FIND_STRATEGY, Python2_FIND_STRATEGY and Python_FIND_STRATEGY.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0093
Added in version 3.15.
FindBoost reports Boost_VERSION in x.y.z format.
In CMake 3.14 and below the module would report the Boost version
number as specified in the preprocessor definition BOOST_VERSION in the
boost/version.hpp file. In CMake 3.15 and later it is preferred that
the reported version number matches the x.y.z format reported by the
CMake package shipped with Boost 1.70.0 and later. The macro value is
still reported in the Boost_VERSION_MACRO variable.
The OLD behavior for this policy is for FindBoost to report
Boost_VERSION as specified in the preprocessor definition BOOST_VERSION
in boost/version.hpp. The NEW behavior for this policy is for FindBoost
to report Boost_VERSION in x.y.z format.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0092
Added in version 3.15.
MSVC warning flags are not in CMAKE_<LANG>_FLAGS by default.
When using MSVC-like compilers in CMake 3.14 and below, warning flags
like /W3 are added to CMAKE_<LANG>_FLAGS by default. This is
problematic for projects that want to choose a different warning level
programmatically. In particular, it requires string editing of the
CMAKE_<LANG>_FLAGS variables with knowledge of the CMake builtin
defaults so they can be replaced.
CMake 3.15 and above prefer to leave out warning flags from the value
of CMAKE_<LANG>_FLAGS by default.
This policy provides compatibility with projects that have not been
updated to expect the lack of warning flags. The policy setting takes
effect as of the first project() or enable_language() command that
initializes CMAKE_<LANG>_FLAGS for a given language <LANG>.
NOTE:
Once the policy has taken effect at the top of a project for a given
language, that choice must be used throughout the tree for that
language. In projects that have nested projects in subdirectories,
be sure to convert everything together.
The OLD behavior for this policy is to place MSVC warning flags in the
default CMAKE_<LANG>_FLAGS cache entries. The NEW behavior for this
policy is to not place MSVC warning flags in the default cache entries.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0091
Added in version 3.15.
MSVC runtime library flags are selected by an abstraction.
Compilers targeting the MSVC ABI have flags to select the MSVC runtime
library. Runtime library selection typically varies with build
configuration because there is a separate runtime library for Debug
builds.
In CMake 3.14 and below, MSVC runtime library selection flags are added
to the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries by CMake
automatically. This allows users to edit their cache entries to adjust
the flags. However, the presence of such default flags is problematic
for projects that want to choose a different runtime library
programmatically. In particular, it requires string editing of the
CMAKE_<LANG>_FLAGS_<CONFIG> variables with knowledge of the CMake
builtin defaults so they can be replaced.
CMake 3.15 and above prefer to leave the MSVC runtime library selection
flags out of the default CMAKE_<LANG>_FLAGS_<CONFIG> values and instead
offer a first-class abstraction. The CMAKE_MSVC_RUNTIME_LIBRARY
variable and MSVC_RUNTIME_LIBRARY target property may be set to select
the MSVC runtime library. If they are not set then CMake uses the
default value MultiThreaded$<$<CONFIG:Debug>:Debug>DLL which is
equivalent to the original flags.
This policy provides compatibility with projects that have not been
updated to be aware of the abstraction. The policy setting takes
effect as of the first project() or enable_language() command that
enables a language whose compiler targets the MSVC ABI.
NOTE:
Once the policy has taken effect at the top of a project, that
choice must be used throughout the tree. In projects that have
nested projects in subdirectories, be sure to convert everything
together.
The OLD behavior for this policy is to place MSVC runtime library flags
in the default CMAKE_<LANG>_FLAGS_<CONFIG> cache entries and ignore the
CMAKE_MSVC_RUNTIME_LIBRARY abstraction. The NEW behavior for this
policy is to not place MSVC runtime library flags in the default cache
entries and use the abstraction instead.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0090
Added in version 3.15.
export(PACKAGE) does not populate package registry by default.
In CMake 3.14 and below the export(PACKAGE) command populated the user
package registry by default and users needed to set the
CMAKE_EXPORT_NO_PACKAGE_REGISTRY to disable it, e.g. in automated build
and packaging environments. Since the user package registry is stored
outside the build tree, this side effect should not be enabled by
default. Therefore CMake 3.15 and above prefer that export(PACKAGE)
does nothing unless an explicit CMAKE_EXPORT_PACKAGE_REGISTRY variable
is set to enable it. This policy provides compatibility with projects
that have not been updated.
The OLD behavior for this policy is for export(PACKAGE) command to
populate the user package registry unless
CMAKE_EXPORT_NO_PACKAGE_REGISTRY is enabled. The NEW behavior is for
export(PACKAGE) command to do nothing unless the
CMAKE_EXPORT_PACKAGE_REGISTRY is enabled.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0089
Added in version 3.15.
Compiler id for IBM Clang-based XL compilers is now XLClang.
CMake 3.15 and above recognize that IBM's Clang-based XL compilers that
define __ibmxl__ are a new front-end distinct from xlc with a different
command line and set of capabilities. CMake now prefers to present
this to projects by setting the CMAKE_<LANG>_COMPILER_ID variable to
XLClang instead of XL. However, existing projects may assume the
compiler id for Clang-based XL is just XL as it was in CMake versions
prior to 3.15. Therefore this policy determines for Clang-based XL
compilers which compiler id to report in the CMAKE_<LANG>_COMPILER_ID
variable after language <LANG> is enabled by the project() or
enable_language() command. The policy must be set prior to the
invocation of either command.
The OLD behavior for this policy is to use compiler id XL. The NEW
behavior for this policy is to use compiler id XLClang.
This policy was introduced in CMake version 3.15. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0089 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.14
CMP0088
Added in version 3.14.
FindBISON runs bison in CMAKE_CURRENT_BINARY_DIR when executing.
The module provides a BISON_TARGET macro which generates BISON output.
In CMake 3.13 and below the macro would generate a custom command that
runs bison in the source directory. CMake 3.14 and later prefer to run
it in the build directory and use CMAKE_CURRENT_BINARY_DIR as the
WORKING_DIRECTORY of its add_custom_command() invocation. This ensures
that any implicitly generated file is written to the build tree rather
than the source.
This policy provides compatibility for projects that have not been
updated to expect the new behavior.
The OLD behavior for this policy is for BISON_TARGET to use the current
source directory for the WORKING_DIRECTORY and where to generate
implicit files. The NEW behavior of this policy is to use the current
binary directory for the WORKING_DIRECTORY and where to generate
implicit files.
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0087
Added in version 3.14.
install(CODE) and install(SCRIPT) support generator expressions.
In CMake 3.13 and earlier, install(CODE) and install(SCRIPT) did not
evaluate generator expressions. CMake 3.14 and later will evaluate
generator expressions for install(CODE) and install(SCRIPT).
The OLD behavior of this policy is for install(CODE) and
install(SCRIPT) to not evaluate generator expressions. The NEW
behavior is to evaluate generator expressions for install(CODE) and
install(SCRIPT).
Note that it is the value of this policy setting at the end of the
directory scope that is important, not its setting at the time of the
call to install(CODE) or install(SCRIPT). This has implications for
calling these commands from places that have their own policy scope but
not their own directory scope (e.g. from files brought in via include()
rather than add_subdirectory()).
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0086
Added in version 3.14.
UseSWIG honors SWIG_MODULE_NAME via -module flag.
Starting with CMake 3.14, UseSWIG passes option -module <module_name>
to SWIG compiler if the file property SWIG_MODULE_NAME is specified.
This policy provides compatibility with projects that expect the legacy
behavior.
The OLD behavior for this policy is to never pass -module option. The
NEW behavior is to pass -module option to SWIG compiler if
SWIG_MODULE_NAME is specified.
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0085
Added in version 3.14.
$<IN_LIST:...> handles empty list items.
In CMake 3.13 and lower, the $<IN_LIST:...> generator expression always
returned 0 if the first argument was empty, even if the list contained
an empty item. This behavior is inconsistent with the IN_LIST behavior
of if(), which this generator expression is meant to emulate. CMake
3.14 and later handles this case correctly.
The OLD behavior of this policy is for $<IN_LIST:...> to always return
0 if the first argument is empty. The NEW behavior is to return 1 if
the first argument is empty and the list contains an empty item.
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0084
Added in version 3.14.
The FindQt module does not exist for find_package().
The existence of FindQt means that for Qt upstream to provide package
config files that can be found by find_package(Qt), the consuming
project has to explicitly specify find_package(Qt CONFIG). Removing
this module gives Qt a path forward for exporting its own config files
which can easily be found by consuming projects.
This policy pretends that CMake's internal FindQt module does not exist
for find_package(). If a project really wants to use Qt 3 or 4, it can
call find_package(Qt[34]), include(FindQt), or add FindQt to their
CMAKE_MODULE_PATH.
The OLD behavior of this policy is for FindQt to exist for
find_package(). The NEW behavior is to pretend that it doesn't exist
for find_package().
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0083
Added in version 3.14.
To control generation of Position Independent Executable (PIE) or not,
some flags are required at link time.
CMake 3.13 and lower did not add these link flags when
POSITION_INDEPENDENT_CODE is set.
The OLD behavior for this policy is to not manage PIE link flags. The
NEW behavior is to add link flags if POSITION_INDEPENDENT_CODE is set:
o Set to TRUE: flags to produce a position independent executable are
passed to the linker step. For example -pie for GCC.
o Set to FALSE: flags not to produce a position independent executable
are passed to the linker step. For example -no-pie for GCC.
o Not set: no flags are passed to the linker step.
Since a given linker may not support PIE flags in all environments in
which it is used, it is the project's responsibility to use the
CheckPIESupported module to check for support to ensure that the
POSITION_INDEPENDENT_CODE target property for executables will be
honored at link time.
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
Android platform has a special handling of PIE so it is not required
to use the CheckPIESupported module to ensure flags are passed to
the linker.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
Examples
Behave like CMake 3.13 and do not apply any PIE flags at link stage.
cmake_minimum_required(VERSION 3.13)
project(foo)
# ...
add_executable(foo ...)
set_property(TARGET foo PROPERTY POSITION_INDEPENDENT_CODE TRUE)
Use the CheckPIESupported module to detect whether PIE is supported by
the current linker and environment. Apply PIE flags only if the linker
supports them.
cmake_minimum_required(VERSION 3.14) # CMP0083 NEW
project(foo)
include(CheckPIESupported)
check_pie_supported()
# ...
add_executable(foo ...)
set_property(TARGET foo PROPERTY POSITION_INDEPENDENT_CODE TRUE)
CMP0082
Added in version 3.14.
Install rules from add_subdirectory() calls are interleaved with those
in caller.
CMake 3.13 and lower ran the install rules from add_subdirectory()
after all other install rules, even if add_subdirectory() was called
before the other install rules. CMake 3.14 and above prefer to
interleave these add_subdirectory() install rules with the others so
that they are run in the order they are declared. This policy provides
compatibility for projects that have not been updated to expect the new
behavior.
The OLD behavior for this policy is to run the install rules from
add_subdirectory() after the other install rules. The NEW behavior for
this policy is to run all install rules in the order they are declared.
This policy was introduced in CMake version 3.14. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0082 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.13
CMP0081
Added in version 3.13.
Relative paths not allowed in LINK_DIRECTORIES target property.
CMake 3.12 and lower allowed the LINK_DIRECTORIES directory property to
contain relative paths. The base path for such relative entries is not
well defined. CMake 3.13 and later will issue a FATAL_ERROR if the
LINK_DIRECTORIES target property (which is initialized by the
LINK_DIRECTORIES directory property) contains a relative path.
The OLD behavior for this policy is not to warn about relative paths in
the LINK_DIRECTORIES target property. The NEW behavior for this policy
is to issue a FATAL_ERROR if LINK_DIRECTORIES contains a relative path.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0080
Added in version 3.13.
BundleUtilities cannot be included at configure time.
The macros provided by BundleUtilities are intended to be invoked at
install time rather than at configure time, because they depend on the
listed targets already existing at the time they are invoked. If they
are invoked at configure time, the targets haven't been built yet, and
the commands will fail.
This policy restricts the inclusion of BundleUtilities to cmake -P
style scripts and install rules. Specifically, it looks for the
presence of CMAKE_GENERATOR and throws a fatal error if it exists.
The OLD behavior of this policy is to allow BundleUtilities to be
included at configure time. The NEW behavior of this policy is to
disallow such inclusion.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0079
Added in version 3.13.
target_link_libraries() allows use with targets in other directories.
Prior to CMake 3.13 the target_link_libraries() command did not accept
targets not created in the calling directory as its first argument for
calls that update the LINK_LIBRARIES of the target itself. It did
accidentally accept targets from other directories on calls that only
update the INTERFACE_LINK_LIBRARIES, but would simply add entries to
the property as if the call were made in the original directory. Thus
link interface libraries specified this way were always looked up by
generators in the scope of the original target rather than in the scope
that called target_link_libraries().
CMake 3.13 now allows the target_link_libraries() command to be called
from any directory to add link dependencies and link interface
libraries to targets created in other directories. The entries are
added to LINK_LIBRARIES and INTERFACE_LINK_LIBRARIES using a special
(internal) suffix to tell the generators to look up the names in the
calling scope rather than the scope that created the target.
This policy provides compatibility with projects that already use
target_link_libraries() with the INTERFACE keyword on a target in
another directory to add INTERFACE_LINK_LIBRARIES entries to be looked
up in the target's directory. Such projects should be updated to be
aware of the new scoping rules in that case.
The OLD behavior of this policy is to disallow target_link_libraries()
calls naming targets from another directory except in the previously
accidentally allowed case of using the INTERFACE keyword only. The NEW
behavior of this policy is to allow all such calls but use the new
scoping rules.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0078
Added in version 3.13.
UseSWIG generates standard target names.
Starting with CMake 3.13, UseSWIG generates now standard target names.
This policy provides compatibility with projects that expect the legacy
behavior.
The OLD behavior for this policy relies on
UseSWIG_TARGET_NAME_PREFERENCE variable that can be used to specify an
explicit preference. The value may be one of:
o LEGACY: legacy strategy is applied. Variable
SWIG_MODULE_<name>_REAL_NAME must be used to get real target name.
This is the default if not specified.
o STANDARD: target name matches specified name.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0077
Added in version 3.13.
option() honors normal variables.
The option() command is typically used to create a cache entry to allow
users to set the option. However, there are cases in which a normal
(non-cached) variable of the same name as the option may be defined by
the project prior to calling the option() command. For example, a
project that embeds another project as a subdirectory may want to
hard-code options of the subproject to build the way it needs.
For historical reasons in CMake 3.12 and below the option() command
removes a normal (non-cached) variable of the same name when:
o a cache entry of the specified name does not exist at all, or
o a cache entry of the specified name exists but has not been given a
type (e.g. via -D<name>=ON on the command line).
In both of these cases (typically on the first run in a new build
tree), the option() command gives the cache entry type BOOL and removes
any normal (non-cached) variable of the same name. In the remaining
case that the cache entry of the specified name already exists and has
a type (typically on later runs in a build tree), the option() command
changes nothing and any normal variable of the same name remains set.
In CMake 3.13 and above the option() command prefers to do nothing when
a normal variable of the given name already exists. It does not create
or update a cache entry or remove the normal variable. The new
behavior is consistent between the first and later runs in a build
tree. This policy provides compatibility with projects that have not
been updated to expect the new behavior.
When the option() command sees a normal variable of the given name:
o The OLD behavior for this policy is to proceed even when a normal
variable of the same name exists. If the cache entry does not
already exist and have a type then it is created and/or given a type
and the normal variable is removed.
o The NEW behavior for this policy is to do nothing when a normal
variable of the same name exists. The normal variable is not
removed. The cache entry is not created or updated and is ignored if
it exists.
See CMP0126 for a similar policy for the set(CACHE) command, but note
that there are some differences in NEW behavior between the two
policies.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
Use the CMAKE_POLICY_DEFAULT_CMP0077 variable to set the policy for a
third-party project in a subdirectory without modifying it.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0076
Added in version 3.13.
The target_sources() command converts relative paths to absolute.
In CMake 3.13 and above, the target_sources() command now converts
relative source file paths to absolute paths in the following cases:
o Source files are added to the target's INTERFACE_SOURCES property.
o The target's SOURCE_DIR property differs from
CMAKE_CURRENT_SOURCE_DIR.
A path that begins with a generator expression is always left
unmodified.
This policy provides compatibility with projects that have not been
updated to expect this behavior. The OLD behavior for this policy is
to leave all relative source file paths unmodified. The NEW behavior
of this policy is to convert relative paths to absolute according to
above rules.
This policy was introduced in CMake version 3.13. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.12
CMP0075
Added in version 3.12.
Include file check macros honor CMAKE_REQUIRED_LIBRARIES.
In CMake 3.12 and above, the
o check_include_file macro in the CheckIncludeFile module, the
o check_include_file_cxx macro in the CheckIncludeFileCXX module, and
the
o check_include_files macro in the CheckIncludeFiles module
now prefer to link the check executable to the libraries listed in the
CMAKE_REQUIRED_LIBRARIES variable. This policy provides compatibility
with projects that have not been updated to expect this behavior.
The OLD behavior for this policy is to ignore CMAKE_REQUIRED_LIBRARIES
in the include file check macros. The NEW behavior of this policy is
to honor CMAKE_REQUIRED_LIBRARIES in the include file check macros.
This policy was introduced in CMake version 3.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0074
Added in version 3.12.
find_package() uses <PackageName>_ROOT variables.
In CMake 3.12 and above the find_package(<PackageName>) command now
searches prefixes specified by the <PackageName>_ROOT CMake variable
and the <PackageName>_ROOT environment variable. Package roots are
maintained as a stack so nested calls to all find_* commands inside
find modules and config packages also search the roots as prefixes.
This policy provides compatibility with projects that have not been
updated to avoid using <PackageName>_ROOT variables for other purposes.
The OLD behavior for this policy is to ignore <PackageName>_ROOT
variables. The NEW behavior for this policy is to use
<PackageName>_ROOT variables.
This policy was introduced in CMake version 3.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0073
Added in version 3.12.
Do not produce legacy _LIB_DEPENDS cache entries.
Ancient CMake versions once used <tgt>_LIB_DEPENDS cache entries to
propagate library link dependencies. This has long been done by other
means, leaving the export_library_dependencies() command as the only
user of these values. That command has long been disallowed by policy
CMP0033, but the <tgt>_LIB_DEPENDS cache entries were left for
compatibility with possible non-standard uses by projects.
CMake 3.12 and above now prefer to not produce these cache entries at
all. This policy provides compatibility with projects that have not
been updated to avoid using them.
The OLD behavior for this policy is to set <tgt>_LIB_DEPENDS cache
entries. The NEW behavior for this policy is to not set them.
This policy was introduced in CMake version 3.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.11
CMP0072
Added in version 3.11.
FindOpenGL prefers GLVND by default when available.
The FindOpenGL module provides an OpenGL::GL target and an
OPENGL_LIBRARIES variable for projects to use for legacy GL interfaces.
When both a legacy GL library (e.g. libGL.so) and GLVND libraries for
OpenGL and GLX (e.g. libOpenGL.so and libGLX.so) are available, the
module must choose between them. It documents an OpenGL_GL_PREFERENCE
variable that can be used to specify an explicit preference. When no
such preference is set, the module must choose a default preference.
CMake 3.11 and above prefer to choose GLVND libraries. This policy
provides compatibility with projects that expect the legacy GL library
to be used.
The OLD behavior for this policy is to set OpenGL_GL_PREFERENCE to
LEGACY. The NEW behavior for this policy is to set
OpenGL_GL_PREFERENCE to GLVND.
This policy was introduced in CMake version 3.11. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.10
CMP0071
Added in version 3.10.
Let AUTOMOC and AUTOUIC process GENERATED files.
Since version 3.10, CMake processes regular and GENERATED source files
in AUTOMOC and AUTOUIC. In earlier CMake versions, only regular source
files were processed. GENERATED source files were ignored silently.
This policy affects how source files that are GENERATED get treated in
AUTOMOC and AUTOUIC.
The OLD behavior for this policy is to ignore GENERATED source files in
AUTOMOC and AUTOUIC.
The NEW behavior for this policy is to process GENERATED source files
in AUTOMOC and AUTOUIC just like regular source files.
NOTE:
To silence the CMP0071 warning source files can be excluded from
AUTOMOC and AUTOUIC processing by setting the source file properties
SKIP_AUTOMOC, SKIP_AUTOUIC or SKIP_AUTOGEN.
Source skip example:
# ...
set_property(SOURCE /path/to/file1.h PROPERTY SKIP_AUTOMOC ON)
set_property(SOURCE /path/to/file2.h PROPERTY SKIP_AUTOUIC ON)
set_property(SOURCE /path/to/file3.h PROPERTY SKIP_AUTOGEN ON)
# ...
This policy was introduced in CMake version 3.10. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0070
Added in version 3.10.
Define file(GENERATE) behavior for relative paths.
CMake 3.10 and newer define that relative paths given to INPUT and
OUTPUT arguments of file(GENERATE) are interpreted relative to the
current source and binary directories, respectively. CMake 3.9 and
lower did not define any behavior for relative paths but did not
diagnose them either and accidentally treated them relative to the
process working directory. Policy CMP0070 provides compatibility with
projects that used the old undefined behavior.
This policy affects behavior of relative paths given to file(GENERATE).
The OLD behavior for this policy is to treat the paths relative to the
working directory of CMake. The NEW behavior for this policy is to
interpret relative paths with respect to the current source or binary
directory of the caller.
This policy was introduced in CMake version 3.10. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.9
CMP0069
Added in version 3.9.
INTERPROCEDURAL_OPTIMIZATION is enforced when enabled.
CMake 3.9 and newer prefer to add IPO flags whenever the
INTERPROCEDURAL_OPTIMIZATION target property is enabled and produce an
error if flags are not known to CMake for the current compiler. Since
a given compiler may not support IPO flags in all environments in which
it is used, it is now the project's responsibility to use the
CheckIPOSupported module to check for support before enabling the
INTERPROCEDURAL_OPTIMIZATION target property. This approach allows a
project to conditionally activate IPO when supported. It also allows
an end user to set the CMAKE_INTERPROCEDURAL_OPTIMIZATION variable in
an environment known to support IPO even if the project does not enable
the property.
Since CMake 3.8 and lower only honored INTERPROCEDURAL_OPTIMIZATION for
the Intel compiler on Linux, some projects may unconditionally enable
the target property. Policy CMP0069 provides compatibility with such
projects.
This policy takes effect whenever the IPO property is enabled. The OLD
behavior for this policy is to add IPO flags only for Intel compiler on
Linux. The NEW behavior for this policy is to add IPO flags for the
current compiler or produce an error if CMake does not know the flags.
This policy was introduced in CMake version 3.9. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
Examples
Behave like CMake 3.8 and do not apply any IPO flags except for Intel
compiler on Linux:
cmake_minimum_required(VERSION 3.8)
project(foo)
# ...
set_property(TARGET ... PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
Use the CheckIPOSupported module to detect whether IPO is supported by
the current compiler, environment, and CMake version. Produce a fatal
error if support is not available:
cmake_minimum_required(VERSION 3.9) # CMP0069 NEW
project(foo)
include(CheckIPOSupported)
check_ipo_supported()
# ...
set_property(TARGET ... PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
Apply IPO flags only if compiler supports it:
cmake_minimum_required(VERSION 3.9) # CMP0069 NEW
project(foo)
include(CheckIPOSupported)
# ...
check_ipo_supported(RESULT result)
if(result)
set_property(TARGET ... PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
endif()
Apply IPO flags without any checks. This may lead to build errors if
IPO is not supported by the compiler in the current environment.
Produce an error if CMake does not know IPO flags for the current
compiler:
cmake_minimum_required(VERSION 3.9) # CMP0069 NEW
project(foo)
# ...
set_property(TARGET ... PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
CMP0068
Added in version 3.9.
RPATH settings on macOS do not affect install_name.
CMake 3.9 and newer remove any effect the following settings may have
on the install_name of a target on macOS:
o BUILD_WITH_INSTALL_RPATH target property
o SKIP_BUILD_RPATH target property
o CMAKE_SKIP_RPATH variable
o CMAKE_SKIP_INSTALL_RPATH variable
Previously, setting BUILD_WITH_INSTALL_RPATH had the effect of setting
both the install_name of a target to INSTALL_NAME_DIR and the RPATH to
INSTALL_RPATH. In CMake 3.9, it only affects setting of RPATH.
However, if one wants INSTALL_NAME_DIR to apply to the target in the
build tree, one may set BUILD_WITH_INSTALL_NAME_DIR.
If SKIP_BUILD_RPATH, CMAKE_SKIP_RPATH or CMAKE_SKIP_INSTALL_RPATH were
used to strip the directory portion of the install_name of a target,
one may set INSTALL_NAME_DIR="" instead.
The OLD behavior of this policy is to use the RPATH settings for
install_name on macOS. The NEW behavior of this policy is to ignore
the RPATH settings for install_name on macOS.
This policy was introduced in CMake version 3.9. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.8
CMP0067
Added in version 3.8.
Honor language standard in try_compile() source-file signature.
The try_compile() source file signature is intended to allow callers to
check whether they will be able to compile a given source file with the
current toolchain. In order to match compiler behavior, any language
standard mode should match. However, CMake 3.7 and below did not do
this. CMake 3.8 and above prefer to honor the language standard
settings for C, CXX (C++), and CUDA using the values of the variables:
o CMAKE_C_STANDARD
o CMAKE_C_STANDARD_REQUIRED
o CMAKE_C_EXTENSIONS
o CMAKE_CXX_STANDARD
o CMAKE_CXX_STANDARD_REQUIRED
o CMAKE_CXX_EXTENSIONS
o CMAKE_CUDA_STANDARD
o CMAKE_CUDA_STANDARD_REQUIRED
o CMAKE_CUDA_EXTENSIONS
This policy provides compatibility for projects that do not expect the
language standard settings to be used automatically.
The OLD behavior of this policy is to ignore language standard setting
variables when generating the try_compile test project. The NEW
behavior of this policy is to honor language standard setting
variables.
This policy was introduced in CMake version 3.8. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0067 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.7
CMP0066
Added in version 3.7.
Honor per-config flags in try_compile() source-file signature.
The source file signature of the try_compile() command uses the value
of the CMAKE_<LANG>_FLAGS variable in the test project so that the test
compilation works as it would in the main project. However, CMake 3.6
and below do not also honor config-specific compiler flags such as
those in the CMAKE_<LANG>_FLAGS_DEBUG variable. CMake 3.7 and above
prefer to honor config-specific compiler flags too. This policy
provides compatibility for projects that do not expect config-specific
compiler flags to be used.
The OLD behavior of this policy is to ignore config-specific flag
variables like CMAKE_<LANG>_FLAGS_DEBUG and only use CMake's built-in
defaults for the current compiler and platform.
The NEW behavior of this policy is to honor config-specific flag
variables like CMAKE_<LANG>_FLAGS_DEBUG.
This policy was introduced in CMake version 3.7. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0066 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.4
CMP0065
Added in version 3.4.
Do not add flags to export symbols from executables without the
ENABLE_EXPORTS target property.
CMake 3.3 and below, for historical reasons, always linked executables
on some platforms with flags like -rdynamic to export symbols from the
executables for use by any plugins they may load via dlopen. CMake 3.4
and above prefer to do this only for executables that are explicitly
marked with the ENABLE_EXPORTS target property.
The OLD behavior of this policy is to always use the additional link
flags when linking executables regardless of the value of the
ENABLE_EXPORTS target property.
The NEW behavior of this policy is to only use the additional link
flags when linking executables if the ENABLE_EXPORTS target property is
set to True.
This policy was introduced in CMake version 3.4. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0065 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0064
Added in version 3.4.
Recognize TEST as a operator for the if() command.
The TEST operator was added to the if() command to determine if a given
test name was created by the add_test() command.
The OLD behavior for this policy is to ignore the TEST operator. The
NEW behavior is to interpret the TEST operator.
This policy was introduced in CMake version 3.4. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.3
CMP0063
Added in version 3.3.
Honor visibility properties for all target types.
The <LANG>_VISIBILITY_PRESET and VISIBILITY_INLINES_HIDDEN target
properties affect visibility of symbols during dynamic linking. When
first introduced these properties affected compilation of sources only
in shared libraries, module libraries, and executables with the
ENABLE_EXPORTS property set. This was sufficient for the basic use
cases of shared libraries and executables with plugins. However, some
sources may be compiled as part of static libraries or object libraries
and then linked into a shared library later. CMake 3.3 and above
prefer to honor these properties for sources compiled in all target
types. This policy preserves compatibility for projects expecting the
properties to work only for some target types.
The OLD behavior for this policy is to ignore the visibility properties
for static libraries, object libraries, and executables without
exports. The NEW behavior for this policy is to honor the visibility
properties for all target types.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0062
Added in version 3.3.
Disallow install() of export() result.
The export() command generates a file containing Imported Targets,
which is suitable for use from the build directory. It is not suitable
for installation because it contains absolute paths to buildsystem
locations, and is particular to a single build configuration.
The install(EXPORT) generates and installs files which contain Imported
Targets. These files are generated with relative paths (unless the
user specifies absolute paths), and are designed for
multi-configuration use. See Creating Packages for more.
CMake 3.3 no longer allows the use of the install(FILES) command with
the result of the export() command.
The OLD behavior for this policy is to allow installing the result of
an export() command. The NEW behavior for this policy is not to allow
installing the result of an export() command.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0061
Added in version 3.3.
CTest does not by default tell make to ignore errors (-i).
The ctest_build() and build_command() commands no longer generate build
commands for Makefile Generators with the -i option. Previously this
was done to help build as much of tested projects as possible.
However, this behavior is not consistent with other generators and also
causes the return code of the make tool to be meaningless.
Of course users may still add this option manually by setting
CTEST_BUILD_COMMAND or the MAKECOMMAND cache entry. See the CTest
Build Step MakeCommand setting documentation for their effects.
The OLD behavior for this policy is to add -i to make calls in CTest.
The NEW behavior for this policy is to not add -i.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0060
Added in version 3.3.
Link libraries by full path even in implicit directories.
Policy CMP0003 was introduced with the intention of always linking
library files by full path when a full path is given to the
target_link_libraries() command. However, on some platforms (e.g.
HP-UX) the compiler front-end adds alternative library search paths for
the current architecture (e.g. /usr/lib/<arch> has alternatives to
libraries in /usr/lib for the current architecture). On such platforms
the find_library() may find a library such as /usr/lib/libfoo.so that
does not belong to the current architecture.
Prior to policy CMP0003 projects would still build in such cases
because the incorrect library path would be converted to -lfoo on the
link line and the linker would find the proper library in the
arch-specific search path provided by the compiler front-end
implicitly. At the time we chose to remain compatible with such
projects by always converting library files found in implicit link
directories to -lfoo flags to ask the linker to search for them. This
approach allowed existing projects to continue to build while still
linking to libraries outside implicit link directories via full path
(such as those in the build tree).
CMake does allow projects to override this behavior by using an
IMPORTED library target with its IMPORTED_LOCATION property set to the
desired full path to a library file. In fact, many Find Modules are
learning to provide Imported Targets instead of just the traditional
Foo_LIBRARIES variable listing library files. However, this makes the
link line generated for a library found by a Find Module depend on
whether it is linked through an imported target or not, which is
inconsistent. Furthermore, this behavior has been a source of
confusion because the generated link line for a library file depends on
its location. It is also problematic for projects trying to link
statically because flags like -Wl,-Bstatic -lfoo -Wl,-Bdynamic may be
used to help the linker select libfoo.a instead of libfoo.so but then
leak dynamic linking to following libraries. (See the
LINK_SEARCH_END_STATIC target property for a solution typically used
for that problem.)
When the special case for libraries in implicit link directories was
first introduced the list of implicit link directories was simply
hard-coded (e.g. /lib, /usr/lib, and a few others). Since that time,
CMake has learned to detect the implicit link directories used by the
compiler front-end. If necessary, the find_library() command could be
taught to use this information to help find libraries of the proper
architecture.
For these reasons, CMake 3.3 and above prefer to drop the special case
and link libraries by full path even when they are in implicit link
directories. Policy CMP0060 provides compatibility for existing
projects.
The OLD behavior for this policy is to ask the linker to search for
libraries whose full paths are known to be in implicit link
directories. The NEW behavior for this policy is to link libraries by
full path even if they are in implicit link directories.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0060 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0059
Added in version 3.3.
Do not treat DEFINITIONS as a built-in directory property.
CMake 3.3 and above no longer make a list of definitions available
through the DEFINITIONS directory property. The COMPILE_DEFINITIONS
directory property may be used instead.
The OLD behavior for this policy is to provide the list of flags given
so far to the add_definitions() command. The NEW behavior is to behave
as a normal user-defined directory property.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0058
Added in version 3.3.
Ninja requires custom command byproducts to be explicit.
When an intermediate file generated during the build is consumed by an
expensive operation or a large tree of dependents, one may reduce the
work needed for an incremental rebuild by updating the file timestamp
only when its content changes. With this approach the generation rule
must have a separate output file that is always updated with a new
timestamp that is newer than any dependencies of the rule so that the
build tool re-runs the rule only when the input changes. We refer to
the separate output file as a rule's witness and the generated file as
a rule's byproduct.
Byproducts may not be listed as outputs because their timestamps are
allowed to be older than the inputs. No build tools (like make) that
existed when CMake was designed have a way to express byproducts.
Therefore CMake versions prior to 3.2 had no way to specify them.
Projects typically left byproducts undeclared in the rules that
generate them. For example:
add_custom_command(
OUTPUT witness.txt
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${CMAKE_CURRENT_SOURCE_DIR}/input.txt
byproduct.txt # timestamp may not change
COMMAND ${CMAKE_COMMAND} -E touch witness.txt
DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/input.txt
)
add_custom_target(Provider DEPENDS witness.txt)
add_custom_command(
OUTPUT generated.c
COMMAND expensive-task -i byproduct.txt -o generated.c
DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/byproduct.txt
)
add_library(Consumer generated.c)
add_dependencies(Consumer Provider)
This works well for all generators except Ninja. The Ninja build tool
sees a rule listing byproduct.txt as a dependency and no rule listing
it as an output. Ninja then complains that there is no way to satisfy
the dependency and stops building even though there are order-only
dependencies that ensure byproduct.txt will exist before its consumers
need it. See discussion of this problem in Ninja Issue 760 for further
details on why Ninja works this way.
Instead of leaving byproducts undeclared in the rules that generate
them, Ninja expects byproducts to be listed along with other outputs.
Such rules may be marked with a restat option that tells Ninja to check
the timestamps of outputs after the rules run. This prevents
byproducts whose timestamps do not change from causing their dependents
to re-build unnecessarily.
Since the above approach does not tell CMake what custom command
generates byproduct.txt, the Ninja generator does not have enough
information to add the byproduct as an output of any rule. CMake
2.8.12 and above work around this problem and allow projects using the
above approach to build by generating phony build rules to tell Ninja
to tolerate such missing files. However, this workaround prevents
Ninja from diagnosing a dependency that is really missing. It also
works poorly in in-source builds where every custom command dependency,
even on source files, needs to be treated this way because CMake does
not have enough information to know which files are generated as
byproducts of custom commands.
Introducing Byproducts
CMake 3.2 introduced the BYPRODUCTS option to the add_custom_command()
and add_custom_target() commands. This option allows byproducts to be
specified explicitly:
add_custom_command(
OUTPUT witness.txt
BYPRODUCTS byproduct.txt # explicit byproduct specification
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${CMAKE_CURRENT_SOURCE_DIR}/input.txt
byproduct.txt # timestamp may not change
...
The BYPRODUCTS option is used by the Ninja generator to list byproducts
among the outputs of the custom commands that generate them, and is
ignored by other generators.
CMake 3.3 and above prefer to require projects to specify custom
command byproducts explicitly so that it can avoid using the phony rule
workaround altogether. Policy CMP0058 was introduced to provide
compatibility with existing projects that still need the workaround.
This policy has no effect on generators other than Ninja. The OLD
behavior for this policy is to generate Ninja phony rules for unknown
dependencies in the build tree. The NEW behavior for this policy is to
not generate these and instead require projects to specify custom
command BYPRODUCTS explicitly.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns when it sees unknown dependencies in out-of-source build trees,
and uses OLD behavior.
The policy setting must be in scope at the end of the top-level
CMakeLists.txt file of the project and has global effect.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0057
Added in version 3.3.
Support new if() IN_LIST operator.
CMake 3.3 adds support for the new IN_LIST operator.
The OLD behavior for this policy is to ignore the IN_LIST operator.
The NEW behavior is to interpret the IN_LIST operator.
This policy was introduced in CMake version 3.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.2
CMP0056
Added in version 3.2.
Honor link flags in try_compile() source-file signature.
The try_compile() command source-file signature generates a
CMakeLists.txt file to build the source file into an executable. In
order to compile the source the same way as it might be compiled by the
calling project, the generated project sets the value of the
CMAKE_<LANG>_FLAGS variable to that in the calling project. The value
of the CMAKE_EXE_LINKER_FLAGS variable may be needed in some cases too,
but CMake 3.1 and lower did not set it in the generated project. CMake
3.2 and above prefer to set it so that linker flags are honored as well
as compiler flags. This policy provides compatibility with the pre-3.2
behavior.
The OLD behavior for this policy is to not set the value of the
CMAKE_EXE_LINKER_FLAGS variable in the generated test project. The NEW
behavior for this policy is to set the value of the
CMAKE_EXE_LINKER_FLAGS variable in the test project to the same as it
is in the calling project.
If the project code does not set the policy explicitly, users may set
it on the command line by defining the CMAKE_POLICY_DEFAULT_CMP0056
variable in the cache.
This policy was introduced in CMake version 3.2. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0056 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0055
Added in version 3.2.
Strict checking for the break() command.
CMake 3.1 and lower allowed calls to the break() command outside of a
loop context and also ignored any given arguments. This was undefined
behavior.
The OLD behavior for this policy is to allow break() to be placed
outside of loop contexts and ignores any arguments. The NEW behavior
for this policy is to issue an error if a misplaced break or any
arguments are found.
This policy was introduced in CMake version 3.2. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.1
CMP0054
Added in version 3.1.
Only interpret if() arguments as variables or keywords when unquoted.
CMake 3.1 and above no longer implicitly dereference variables or
interpret keywords in an if() command argument when it is a Quoted
Argument or a Bracket Argument.
The OLD behavior for this policy is to dereference variables and
interpret keywords even if they are quoted or bracketed. The NEW
behavior is to not dereference variables or interpret keywords that
have been quoted or bracketed.
Given the following partial example:
set(A E)
set(E "")
if("${A}" STREQUAL "")
message("Result is TRUE before CMake 3.1 or when CMP0054 is OLD")
else()
message("Result is FALSE in CMake 3.1 and above if CMP0054 is NEW")
endif()
After explicit expansion of variables this gives:
if("E" STREQUAL "")
With the policy set to OLD implicit expansion reduces this semantically
to:
if("" STREQUAL "")
With the policy set to NEW the quoted arguments will not be further
dereferenced:
if("E" STREQUAL "")
This policy was introduced in CMake version 3.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0053
Added in version 3.1.
Simplify variable reference and escape sequence evaluation.
CMake 3.1 introduced a much faster implementation of evaluation of the
Variable References and Escape Sequences documented in the
cmake-language(7) manual. While the behavior is identical to the
legacy implementation in most cases, some corner cases were cleaned up
to simplify the behavior. Specifically:
o Expansion of @VAR@ reference syntax defined by the configure_file()
and string(CONFIGURE) commands is no longer performed in other
contexts.
o Literal ${VAR} reference syntax may contain only alphanumeric
characters (A-Z, a-z, 0-9) and the characters _, ., /, -, and +.
Note that $ is technically allowed in the NEW behavior, but is
invalid for OLD behavior. This is due to an oversight during the
implementation of CMP0053 and its use as a literal variable reference
is discouraged for this reason. Variables with other characters in
their name may still be referenced indirectly, e.g.
set(varname "otherwise & disallowed $ characters")
message("${${varname}}")
o The setting of policy CMP0010 is not considered, so improper variable
reference syntax is always an error.
o More characters are allowed to be escaped in variable names.
Previously, only ()#" \@^ were valid characters to escape. Now any
non-alphanumeric, non-semicolon, non-NUL character may be escaped
following the escape_identity production in the Escape Sequences
section of the cmake-language(7) manual.
The OLD behavior for this policy is to honor the legacy behavior for
variable references and escape sequences. The NEW behavior is to use
the simpler variable expansion and escape sequence evaluation rules.
This policy was introduced in CMake version 3.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0052
Added in version 3.1.
Reject source and build dirs in installed
INTERFACE_INCLUDE_DIRECTORIES.
CMake 3.0 and lower allowed subdirectories of the source directory or
build directory to be in the INTERFACE_INCLUDE_DIRECTORIES of installed
and exported targets, if the directory was also a subdirectory of the
installation prefix. This makes the installation depend on the
existence of the source dir or binary dir, and the installation will be
broken if either are removed after installation.
See Include Directories and Usage Requirements for more on specifying
include directories for targets.
The OLD behavior for this policy is to export the content of the
INTERFACE_INCLUDE_DIRECTORIES with the source or binary directory. The
NEW behavior for this policy is to issue an error if such a directory
is used.
This policy was introduced in CMake version 3.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0051
Added in version 3.1.
List TARGET_OBJECTS in SOURCES target property.
CMake 3.0 and lower did not include the TARGET_OBJECTS generator
expression when returning the SOURCES target property.
Configure-time CMake code is not able to handle generator expressions.
If using the SOURCES target property at configure time, it may be
necessary to first remove generator expressions using the
string(GENEX_STRIP) command. Generate-time CMake code such as
file(GENERATE) can handle the content without stripping.
The OLD behavior for this policy is to omit TARGET_OBJECTS expressions
from the SOURCES target property. The NEW behavior for this policy is
to include TARGET_OBJECTS expressions in the output.
This policy was introduced in CMake version 3.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 3.0
CMP0050
Disallow add_custom_command SOURCE signatures.
CMake 2.8.12 and lower allowed a signature for add_custom_command()
which specified an input to a command. This was undocumented behavior.
Modern use of CMake associates custom commands with their output,
rather than their input.
The OLD behavior for this policy is to allow the use of
add_custom_command() SOURCE signatures. The NEW behavior for this
policy is to issue an error if such a signature is used.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0049
Do not expand variables in target source entries.
CMake 2.8.12 and lower performed an extra layer of variable expansion
when evaluating source file names:
set(a_source foo.c)
add_executable(foo \${a_source})
This was undocumented behavior.
The OLD behavior for this policy is to expand such variables when
processing the target sources. The NEW behavior for this policy is to
issue an error if such variables need to be expanded.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0048
The project() command manages VERSION variables.
CMake version 3.0 introduced the VERSION option of the project()
command to specify a project version as well as the name. In order to
keep PROJECT_VERSION and related variables consistent with variable
PROJECT_NAME it is necessary to set the VERSION variables to the empty
string when no VERSION is given to project(). However, this can change
behavior for existing projects that set VERSION variables themselves
since project() may now clear them. This policy controls the behavior
for compatibility with such projects.
The OLD behavior for this policy is to leave VERSION variables
untouched. The NEW behavior for this policy is to set VERSION as
documented by the project() command.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0047
Use QCC compiler id for the qcc drivers on QNX.
CMake 3.0 and above recognize that the QNX qcc compiler driver is
different from the GNU compiler. CMake now prefers to present this to
projects by setting the CMAKE_<LANG>_COMPILER_ID variable to QCC
instead of GNU. However, existing projects may assume the compiler id
for QNX qcc is just GNU as it was in CMake versions prior to 3.0.
Therefore this policy determines for QNX qcc which compiler id to
report in the CMAKE_<LANG>_COMPILER_ID variable after language <LANG>
is enabled by the project() or enable_language() command. The policy
must be set prior to the invocation of either command.
The OLD behavior for this policy is to use the GNU compiler id for the
qcc and QCC compiler drivers. The NEW behavior for this policy is to
use the QCC compiler id for those drivers.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0047 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0046
Error on non-existent dependency in add_dependencies.
CMake 2.8.12 and lower silently ignored non-existent dependencies
listed in the add_dependencies() command.
The OLD behavior for this policy is to silently ignore non-existent
dependencies. The NEW behavior for this policy is to report an error if
non-existent dependencies are listed in the add_dependencies() command.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0045
Error on non-existent target in get_target_property.
In CMake 2.8.12 and lower, the get_target_property() command accepted a
non-existent target argument without issuing any error or warning. The
result variable is set to a -NOTFOUND value.
The OLD behavior for this policy is to issue no warning and set the
result variable to a -NOTFOUND value. The NEW behavior for this policy
is to issue a FATAL_ERROR if the command is called with a non-existent
target.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0044
Case sensitive <LANG>_COMPILER_ID generator expressions
CMake 2.8.12 introduced the <LANG>_COMPILER_ID generator expressions to
allow comparison of the CMAKE_<LANG>_COMPILER_ID with a test value.
The possible valid values are lowercase, but the comparison with the
test value was performed case-insensitively.
The OLD behavior for this policy is to perform a case-insensitive
comparison with the value in the <LANG>_COMPILER_ID expression. The NEW
behavior for this policy is to perform a case-sensitive comparison with
the value in the <LANG>_COMPILER_ID expression.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0043
Ignore COMPILE_DEFINITIONS_<Config> properties
CMake 2.8.12 and lower allowed setting the COMPILE_DEFINITIONS_<CONFIG>
target property and COMPILE_DEFINITIONS_<CONFIG> directory property to
apply configuration-specific compile definitions.
Since CMake 2.8.10, the COMPILE_DEFINITIONS property has supported
generator expressions for setting configuration-dependent content. The
continued existence of the suffixed variables is redundant, and causes
a maintenance burden. Population of the COMPILE_DEFINITIONS_DEBUG
property may be replaced with a population of COMPILE_DEFINITIONS
directly or via target_compile_definitions():
# Old Interfaces:
set_property(TARGET tgt APPEND PROPERTY
COMPILE_DEFINITIONS_DEBUG DEBUG_MODE
)
set_property(DIRECTORY APPEND PROPERTY
COMPILE_DEFINITIONS_DEBUG DIR_DEBUG_MODE
)
# New Interfaces:
set_property(TARGET tgt APPEND PROPERTY
COMPILE_DEFINITIONS $<$OLD behavior for this policy is to consume the content of the
suffixed COMPILE_DEFINITIONS_<CONFIG> target property when generating
the compilation command. The NEW behavior for this policy is to ignore
the content of the COMPILE_DEFINITIONS_<CONFIG> target property .
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0042
MACOSX_RPATH is enabled by default.
CMake 2.8.12 and newer has support for using @rpath in a target's
install name. This was enabled by setting the target property
MACOSX_RPATH. The @rpath in an install name is a more flexible and
powerful mechanism than @executable_path or @loader_path for locating
shared libraries.
CMake 3.0 and later prefer this property to be ON by default. Projects
wanting @rpath in a target's install name may remove any setting of the
INSTALL_NAME_DIR and CMAKE_INSTALL_NAME_DIR variables.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0041
Error on relative include with generator expression.
Diagnostics in CMake 2.8.12 and lower silently ignored an entry in the
INTERFACE_INCLUDE_DIRECTORIES of a target if it contained a generator
expression at any position.
The path entries in that target property should not be relative.
High-level API should ensure that by adding either a source directory
or a install directory prefix, as appropriate.
As an additional diagnostic, the INTERFACE_INCLUDE_DIRECTORIES
generated on an IMPORTED target for the install location should not
contain paths in the source directory or the build directory.
The OLD behavior for this policy is to ignore relative path entries if
they contain a generator expression. The NEW behavior for this policy
is to report an error if a generator expression appears in another
location and the path is relative.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0040
The target in the TARGET signature of add_custom_command() must exist
and must be defined in the current directory.
CMake 2.8.12 and lower silently ignored a custom command created with
the TARGET signature of add_custom_command() if the target is unknown
or was defined outside the current directory.
The OLD behavior for this policy is to ignore custom commands for
unknown targets. The NEW behavior for this policy is to report an
error if the target referenced in add_custom_command() is unknown or
was defined outside the current directory.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0039
Utility targets may not have link dependencies.
CMake 2.8.12 and lower allowed using utility targets in the left hand
side position of the target_link_libraries() command. This is an
indicator of a bug in user code.
The OLD behavior for this policy is to ignore attempts to set the link
libraries of utility targets. The NEW behavior for this policy is to
report an error if an attempt is made to set the link libraries of a
utility target.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0038
Targets may not link directly to themselves.
CMake 2.8.12 and lower allowed a build target to link to itself
directly with a target_link_libraries() call. This is an indicator of a
bug in user code.
The OLD behavior for this policy is to ignore targets which list
themselves in their own link implementation. The NEW behavior for this
policy is to report an error if a target attempts to link to itself.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0037
Target names should not be reserved and should match a validity
pattern.
CMake 2.8.12 and lower allowed creating targets using add_library(),
add_executable() and add_custom_target() with unrestricted choice for
the target name. Newer cmake features such as
cmake-generator-expressions(7) and some diagnostics expect target names
to match a restricted pattern.
Target names may contain upper and lower case letters, numbers, the
underscore character (_), dot(.), plus(+) and minus(-). As a special
case, ALIAS and IMPORTED targets may contain two consecutive colons.
Target names reserved by one or more CMake generators are not allowed.
Among others these include all, clean, help, and install.
Target names associated with optional features, such as test and
package, may also be reserved. CMake 3.10 and below always reserve
them. CMake 3.11 and above reserve them only when the corresponding
feature is enabled (e.g. by including the CTest or CPack modules).
The OLD behavior for this policy is to allow creating targets with
reserved names or which do not match the validity pattern. The NEW
behavior for this policy is to report an error if an add_* command is
used with an invalid target name.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0036
The build_name() command should not be called.
This command was added in May 2001 to compute a name for the current
operating system and compiler combination. The command has long been
documented as discouraged and replaced by the CMAKE_SYSTEM and
CMAKE_<LANG>_COMPILER variables.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0035
The variable_requires() command should not be called.
This command was introduced in November 2001 to perform some
conditional logic. It has long been replaced by the if() command.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0034
The utility_source() command should not be called.
This command was introduced in March 2001 to help build executables
used to generate other files. This approach has long been replaced by
add_executable() combined with add_custom_command().
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0033
The export_library_dependencies() command should not be called.
This command was added in January 2003 to export <tgt>_LIB_DEPENDS
internal CMake cache entries to a file for installation with a project.
This was used at the time to allow transitive link dependencies to work
for applications outside of the original build tree of a project. The
functionality has been superseded by the export() and install(EXPORT)
commands.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0032
The output_required_files() command should not be called.
This command was added in June 2001 to expose the then-current CMake
implicit dependency scanner. CMake's real implicit dependency scanner
has evolved since then but is not exposed through this command. The
scanning capabilities of this command are very limited and this
functionality is better achieved through dedicated outside tools.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0031
The load_command() command should not be called.
This command was added in August 2002 to allow projects to add
arbitrary commands implemented in C or C++. However, it does not work
when the toolchain in use does not match the ABI of the CMake process.
It has been mostly superseded by the macro() and function() commands.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0030
The use_mangled_mesa() command should not be called.
This command was created in September 2001 to support VTK before modern
CMake language and custom command capabilities. VTK has not used it in
years.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0029
The subdir_depends() command should not be called.
The implementation of this command has been empty since December 2001
but was kept in CMake for compatibility for a long time.
CMake >= 3.0 prefer that this command never be called. The OLD
behavior for this policy is to allow the command to be called. The NEW
behavior for this policy is to issue a FATAL_ERROR when the command is
called.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0028
Double colon in target name means ALIAS or IMPORTED target.
CMake 2.8.12 and lower allowed the use of targets and files with double
colons in target_link_libraries(), with some buildsystem generators.
The use of double-colons is a common pattern used to namespace IMPORTED
targets and ALIAS targets. When computing the link dependencies of a
target, the name of each dependency could either be a target, or a file
on disk. Previously, if a target was not found with a matching name,
the name was considered to refer to a file on disk. This can lead to
confusing error messages if there is a typo in what should be a target
name.
See also the LINK_LIBRARIES_ONLY_TARGETS target property.
The OLD behavior for this policy is to search for targets, then files
on disk, even if the search term contains double-colons. The NEW
behavior for this policy is to issue a FATAL_ERROR if a link dependency
contains double-colons but is not an IMPORTED target or an ALIAS
target.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0027
Conditionally linked imported targets with missing include directories.
CMake 2.8.11 introduced introduced the concept of
INTERFACE_INCLUDE_DIRECTORIES, and a check at cmake time that the
entries in the INTERFACE_INCLUDE_DIRECTORIES of an IMPORTED target
actually exist. CMake 2.8.11 also introduced generator expression
support in the target_link_libraries() command. However, if an
imported target is linked as a result of a generator expression
evaluation, the entries in the INTERFACE_INCLUDE_DIRECTORIES of that
target were not checked for existence as they should be.
The OLD behavior of this policy is to report a warning if an entry in
the INTERFACE_INCLUDE_DIRECTORIES of a generator-expression
conditionally linked IMPORTED target does not exist.
The NEW behavior of this policy is to report an error if an entry in
the INTERFACE_INCLUDE_DIRECTORIES of a generator-expression
conditionally linked IMPORTED target does not exist.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0026
Disallow use of the LOCATION property for build targets.
CMake 2.8.12 and lower allowed reading the LOCATION target property
(and configuration-specific variants) to determine the eventual
location of build targets. This relies on the assumption that all
necessary information is available at configure-time to determine the
final location and filename of the target. However, this property is
not fully determined until later at generate-time. At generate time,
the $<TARGET_FILE> generator expression can be used to determine the
eventual LOCATION of a target output.
Code which reads the LOCATION target property can be ported to use the
$<TARGET_FILE> generator expression together with the file(GENERATE)
subcommand to generate a file containing the target location.
The OLD behavior for this policy is to allow reading the LOCATION
properties from build-targets. The NEW behavior for this policy is to
not to allow reading the LOCATION properties from build-targets.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0025
Compiler id for Apple Clang is now AppleClang.
CMake 3.0 and above recognize that Apple Clang is a different compiler
than upstream Clang and that they have different version numbers.
CMake now prefers to present this to projects by setting the
CMAKE_<LANG>_COMPILER_ID variable to AppleClang instead of Clang.
However, existing projects may assume the compiler id for Apple Clang
is just Clang as it was in CMake versions prior to 3.0. Therefore this
policy determines for Apple Clang which compiler id to report in the
CMAKE_<LANG>_COMPILER_ID variable after language <LANG> is enabled by
the project() or enable_language() command. The policy must be set
prior to the invocation of either command.
The OLD behavior for this policy is to use compiler id Clang. The NEW
behavior for this policy is to use compiler id AppleClang.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
does not warn by default, and uses OLD behavior.
See documentation of the CMAKE_POLICY_WARNING_CMP0025 variable to
control the warning.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0024
Disallow include export result.
CMake 2.8.12 and lower allowed use of the include() command with the
result of the export() command. This relies on the assumption that the
export() command has an immediate effect at configure-time during a
cmake run. Certain properties of targets are not fully determined
until later at generate-time, such as the link language and complete
list of link libraries. Future refactoring will change the effect of
the export() command to be executed at generate-time. Use ALIAS
targets instead in cases where the goal is to refer to targets by
another name.
The OLD behavior for this policy is to allow including the result of an
export() command. The NEW behavior for this policy is not to allow
including the result of an export() command.
This policy was introduced in CMake version 3.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 2.8
CMP0023
Plain and keyword target_link_libraries() signatures cannot be mixed.
CMake 2.8.12 introduced the target_link_libraries() signature using the
PUBLIC, PRIVATE, and INTERFACE keywords to generalize the LINK_PUBLIC
and LINK_PRIVATE keywords introduced in CMake 2.8.7. Use of signatures
with any of these keywords sets the link interface of a target
explicitly, even if empty. This produces confusing behavior when used
in combination with the historical behavior of the plain
target_link_libraries() signature. For example, consider the code:
target_link_libraries(mylib A)
target_link_libraries(mylib PRIVATE B)
After the first line the link interface has not been set explicitly so
CMake would use the link implementation, A, as the link interface.
However, the second line sets the link interface to empty. In order to
avoid this subtle behavior CMake now prefers to disallow mixing the
plain and keyword signatures of target_link_libraries() for a single
target.
The OLD behavior for this policy is to allow keyword and plain
target_link_libraries() signatures to be mixed. The NEW behavior for
this policy is to not to allow mixing of the keyword and plain
signatures.
This policy was introduced in CMake version 2.8.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0022
INTERFACE_LINK_LIBRARIES defines the link interface.
CMake 2.8.11 constructed the 'link interface' of a target from
properties matching (IMPORTED_)?LINK_INTERFACE_LIBRARIES(_<CONFIG>)?.
The modern way to specify config-sensitive content is to use generator
expressions and the IMPORTED_ prefix makes uniform processing of the
link interface with generator expressions impossible. The
INTERFACE_LINK_LIBRARIES target property was introduced as a
replacement in CMake 2.8.12. This new property is named consistently
with the INTERFACE_COMPILE_DEFINITIONS, INTERFACE_INCLUDE_DIRECTORIES
and INTERFACE_COMPILE_OPTIONS properties. For in-build targets, CMake
will use the INTERFACE_LINK_LIBRARIES property as the source of the
link interface only if policy CMP0022 is NEW. When exporting a target
which has this policy set to NEW, only the INTERFACE_LINK_LIBRARIES
property will be processed and generated for the IMPORTED target by
default. A new option to the install(EXPORT) and export commands
allows export of the old-style properties for compatibility with
downstream users of CMake versions older than 2.8.12. The
target_link_libraries() command will no longer populate the properties
matching LINK_INTERFACE_LIBRARIES(_<CONFIG>)? if this policy is NEW.
Warning-free future-compatible code which works with CMake 2.8.7
onwards can be written by using the LINK_PRIVATE and LINK_PUBLIC
keywords of target_link_libraries().
The OLD behavior for this policy is to ignore the
INTERFACE_LINK_LIBRARIES property for in-build targets. The NEW
behavior for this policy is to use the INTERFACE_LINK_LIBRARIES
property for in-build targets, and ignore the old properties matching
(IMPORTED_)?LINK_INTERFACE_LIBRARIES(_<CONFIG>)?.
This policy was introduced in CMake version 2.8.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0021
Fatal error on relative paths in INCLUDE_DIRECTORIES target property.
CMake 2.8.10.2 and lower allowed the INCLUDE_DIRECTORIES target
property to contain relative paths. The base path for such relative
entries is not well defined. CMake 2.8.12 issues a FATAL_ERROR if the
INCLUDE_DIRECTORIES property contains a relative path.
The OLD behavior for this policy is not to warn about relative paths in
the INCLUDE_DIRECTORIES target property. The NEW behavior for this
policy is to issue a FATAL_ERROR if INCLUDE_DIRECTORIES contains a
relative path.
This policy was introduced in CMake version 2.8.12. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0020
Automatically link Qt executables to qtmain target on Windows.
CMake 2.8.10 and lower required users of Qt to always specify a link
dependency to the qtmain.lib static library manually on Windows. CMake
2.8.11 gained the ability to evaluate generator expressions while
determining the link dependencies from IMPORTED targets. This allows
CMake itself to automatically link executables which link to Qt to the
qtmain.lib library when using IMPORTED Qt targets. For applications
already linking to qtmain.lib, this should have little impact. For
applications which supply their own alternative WinMain implementation
and for applications which use the QAxServer library, this automatic
linking will need to be disabled as per the documentation.
The OLD behavior for this policy is not to link executables to
qtmain.lib automatically when they link to the QtCore IMPORTED target.
The NEW behavior for this policy is to link executables to qtmain.lib
automatically when they link to QtCore IMPORTED target.
This policy was introduced in CMake version 2.8.11. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0019
Do not re-expand variables in include and link information.
CMake 2.8.10 and lower re-evaluated values given to the
include_directories, link_directories, and link_libraries commands to
expand any leftover variable references at the end of the configuration
step. This was for strict compatibility with VERY early CMake versions
because all variable references are now normally evaluated during CMake
language processing. CMake 2.8.11 and higher prefer to skip the extra
evaluation.
The OLD behavior for this policy is to re-evaluate the values for
strict compatibility. The NEW behavior for this policy is to leave the
values untouched.
This policy was introduced in CMake version 2.8.11. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0018
Ignore CMAKE_SHARED_LIBRARY_<Lang>_FLAGS variable.
CMake 2.8.8 and lower compiled sources in SHARED and MODULE libraries
using the value of the undocumented CMAKE_SHARED_LIBRARY_<Lang>_FLAGS
platform variable. The variable contained platform-specific flags
needed to compile objects for shared libraries. Typically it included
a flag such as -fPIC for position independent code but also included
other flags needed on certain platforms. CMake 2.8.9 and higher prefer
instead to use the POSITION_INDEPENDENT_CODE target property to
determine what targets should be position independent, and new
undocumented platform variables to select flags while ignoring
CMAKE_SHARED_LIBRARY_<Lang>_FLAGS completely.
The default for either approach produces identical compilation flags,
but if a project modifies CMAKE_SHARED_LIBRARY_<Lang>_FLAGS from its
original value this policy determines which approach to use.
The OLD behavior for this policy is to ignore the
POSITION_INDEPENDENT_CODE property for all targets and use the modified
value of CMAKE_SHARED_LIBRARY_<Lang>_FLAGS for SHARED and MODULE
libraries.
The NEW behavior for this policy is to ignore
CMAKE_SHARED_LIBRARY_<Lang>_FLAGS whether it is modified or not and
honor the POSITION_INDEPENDENT_CODE target property.
This policy was introduced in CMake version 2.8.9. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0017
Prefer files from the CMake module directory when including from there.
Starting with CMake 2.8.4, if a cmake-module shipped with CMake (i.e.
located in the CMake module directory) calls include() or
find_package(), the files located in the CMake module directory are
preferred over the files in CMAKE_MODULE_PATH. This makes sure that
the modules belonging to CMake always get those files included which
they expect, and against which they were developed and tested. In all
other cases, the files found in CMAKE_MODULE_PATH still take precedence
over the ones in the CMake module directory. The OLD behavior is to
always prefer files from CMAKE_MODULE_PATH over files from the CMake
modules directory.
This policy was introduced in CMake version 2.8.4. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0016
target_link_libraries() reports error if its only argument is not a
target.
In CMake 2.8.2 and lower the target_link_libraries() command silently
ignored if it was called with only one argument, and this argument
wasn't a valid target. In CMake 2.8.3 and above it reports an error in
this case.
This policy was introduced in CMake version 2.8.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0015
link_directories() treats paths relative to the source dir.
In CMake 2.8.0 and lower the link_directories() command passed relative
paths unchanged to the linker. In CMake 2.8.1 and above the
link_directories() command prefers to interpret relative paths with
respect to CMAKE_CURRENT_SOURCE_DIR, which is consistent with
include_directories() and other commands. The OLD behavior for this
policy is to use relative paths verbatim in the linker command. The
NEW behavior for this policy is to convert relative paths to absolute
paths by appending the relative path to CMAKE_CURRENT_SOURCE_DIR.
This policy was introduced in CMake version 2.8.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0014
Input directories must have CMakeLists.txt.
CMake versions before 2.8 silently ignored missing CMakeLists.txt files
in directories referenced by add_subdirectory() or subdirs(), treating
them as if present but empty. In CMake 2.8.0 and above this
cmake_policy() determines whether or not the case is an error. The OLD
behavior for this policy is to silently ignore the problem. The NEW
behavior for this policy is to report an error.
This policy was introduced in CMake version 2.8.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0013
Duplicate binary directories are not allowed.
CMake 2.6.3 and below silently permitted add_subdirectory() calls to
create the same binary directory multiple times. During build system
generation files would be written and then overwritten in the build
tree and could lead to strange behavior. CMake 2.6.4 and above
explicitly detect duplicate binary directories. CMake 2.6.4 always
considers this case an error. In CMake 2.8.0 and above this policy
determines whether or not the case is an error. The OLD behavior for
this policy is to allow duplicate binary directories. The NEW behavior
for this policy is to disallow duplicate binary directories with an
error.
This policy was introduced in CMake version 2.8.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0012
if() recognizes numbers and boolean constants.
In CMake versions 2.6.4 and lower the if() command implicitly
dereferenced arguments corresponding to variables, even those named
like numbers or boolean constants, except for 0 and 1. Numbers and
boolean constants such as true, false, yes, no, on, off, y, n,
notfound, ignore (all case insensitive) were recognized in some cases
but not all. For example, the code if(TRUE) might have evaluated as
false. Numbers such as 2 were recognized only in boolean expressions
like if(NOT 2) (leading to false) but not as a single-argument like
if(2) (also leading to false). Later versions of CMake prefer to treat
numbers and boolean constants literally, so they should not be used as
variable names.
The OLD behavior for this policy is to implicitly dereference variables
named like numbers and boolean constants. The NEW behavior for this
policy is to recognize numbers and boolean constants without
dereferencing variables with such names.
This policy was introduced in CMake version 2.8.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
POLICIES INTRODUCED BY CMAKE 2.6
CMP0011
Included scripts do automatic cmake_policy() PUSH and POP.
In CMake 2.6.2 and below, CMake Policy settings in scripts loaded by
the include() and find_package() commands would affect the includer.
Explicit invocations of cmake_policy(PUSH) and cmake_policy(POP) were
required to isolate policy changes and protect the includer. While
some scripts intend to affect the policies of their includer, most do
not. In CMake 2.6.3 and above, include() and find_package() by default
PUSH and POP an entry on the policy stack around an included script,
but provide a NO_POLICY_SCOPE option to disable it. This policy
determines whether or not to imply NO_POLICY_SCOPE for compatibility.
The OLD behavior for this policy is to imply NO_POLICY_SCOPE for
include() and find_package() commands. The NEW behavior for this
policy is to allow the commands to do their default cmake_policy PUSH
and POP.
This policy was introduced in CMake version 2.6.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0010
Bad variable reference syntax is an error.
In CMake 2.6.2 and below, incorrect variable reference syntax such as a
missing close-brace (${FOO) was reported but did not stop processing of
CMake code. This policy determines whether a bad variable reference is
an error. The OLD behavior for this policy is to warn about the error,
leave the string untouched, and continue. The NEW behavior for this
policy is to report an error.
If CMP0053 is set to NEW, this policy has no effect and is treated as
always being NEW.
This policy was introduced in CMake version 2.6.3. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0009
FILE GLOB_RECURSE calls should not follow symlinks by default.
In CMake 2.6.1 and below, file(GLOB_RECURSE) calls would follow through
symlinks, sometimes coming up with unexpectedly large result sets
because of symlinks to top level directories that contain hundreds of
thousands of files.
This policy determines whether or not to follow symlinks encountered
during a file(GLOB_RECURSE) call. The OLD behavior for this policy is
to follow the symlinks. The NEW behavior for this policy is not to
follow the symlinks by default, but only if FOLLOW_SYMLINKS is given as
an additional argument to the FILE command.
This policy was introduced in CMake version 2.6.2. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0008
Libraries linked by full-path must have a valid library file name.
In CMake 2.4 and below it is possible to write code like
target_link_libraries(myexe /full/path/to/somelib)
where somelib is supposed to be a valid library file name such as
libsomelib.a or somelib.lib. For Makefile generators this produces an
error at build time because the dependency on the full path cannot be
found. For Visual Studio Generators IDE and Xcode generators this used
to work by accident because CMake would always split off the library
directory and ask the linker to search for the library by name
(-lsomelib or somelib.lib). Despite the failure with Makefiles, some
projects have code like this and build only with Visual Studio and/or
Xcode. This version of CMake prefers to pass the full path directly to
the native build tool, which will fail in this case because it does not
name a valid library file.
This policy determines what to do with full paths that do not appear to
name a valid library file. The OLD behavior for this policy is to
split the library name from the path and ask the linker to search for
it. The NEW behavior for this policy is to trust the given path and
pass it directly to the native build tool unchanged.
This policy was introduced in CMake version 2.6.1. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0007
list command no longer ignores empty elements.
This policy determines whether the list command will ignore empty
elements in the list. CMake 2.4 and below list commands ignored all
empty elements in the list. For example, a;b;;c would have length 3
and not 4. The OLD behavior for this policy is to ignore empty list
elements. The NEW behavior for this policy is to correctly count empty
elements in a list.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0006
Installing MACOSX_BUNDLE targets requires a BUNDLE DESTINATION.
This policy determines whether the install(TARGETS) command must be
given a BUNDLE DESTINATION when asked to install a target with the
MACOSX_BUNDLE property set. CMake 2.4 and below did not distinguish
application bundles from normal executables when installing targets.
CMake 2.6 provides a BUNDLE option to the install(TARGETS) command that
specifies rules specific to application bundles on the Mac. Projects
should use this option when installing a target with the MACOSX_BUNDLE
property set.
The OLD behavior for this policy is to fall back to the RUNTIME
DESTINATION if a BUNDLE DESTINATION is not given. The NEW behavior for
this policy is to produce an error if a bundle target is installed
without a BUNDLE DESTINATION.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0005
Preprocessor definition values are now escaped automatically.
This policy determines whether or not CMake should generate escaped
preprocessor definition values added via add_definitions. CMake
versions 2.4 and below assumed that only trivial values would be given
for macros in add_definitions calls. It did not attempt to escape
non-trivial values such as string literals in generated build rules.
CMake versions 2.6 and above support escaping of most values, but
cannot assume the user has not added escapes already in an attempt to
work around limitations in earlier versions.
The OLD behavior for this policy is to place definition values given to
add_definitions directly in the generated build rules without
attempting to escape anything. The NEW behavior for this policy is to
generate correct escapes for all native build tools automatically. See
documentation of the COMPILE_DEFINITIONS target property for
limitations of the escaping implementation.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0004
Libraries linked may not have leading or trailing whitespace.
CMake versions 2.4 and below silently removed leading and trailing
whitespace from libraries linked with code like
target_link_libraries(myexe " A ")
This could lead to subtle errors in user projects.
The OLD behavior for this policy is to silently remove leading and
trailing whitespace. The NEW behavior for this policy is to diagnose
the existence of such whitespace as an error. The setting for this
policy used when checking the library names is that in effect when the
target is created by an add_executable() or add_library() command.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0003
Libraries linked via full path no longer produce linker search paths.
This policy affects how libraries whose full paths are NOT known are
found at link time, but was created due to a change in how CMake deals
with libraries whose full paths are known. Consider the code
target_link_libraries(myexe /path/to/libA.so)
CMake 2.4 and below implemented linking to libraries whose full paths
are known by splitting them on the link line into separate components
consisting of the linker search path and the library name. The example
code might have produced something like
... -L/path/to -lA ...
in order to link to library A. An analysis was performed to order
multiple link directories such that the linker would find library A in
the desired location, but there are cases in which this does not work.
CMake versions 2.6 and above use the more reliable approach of passing
the full path to libraries directly to the linker in most cases. The
example code now produces something like
... /path/to/libA.so ....
Unfortunately this change can break code like
target_link_libraries(myexe /path/to/libA.so B)
where B is meant to find /path/to/libB.so. This code is wrong because
the user is asking the linker to find library B but has not provided a
linker search path (which may be added with the link_directories
command). However, with the old linking implementation the code would
work accidentally because the linker search path added for library A
allowed library B to be found.
In order to support projects depending on linker search paths added by
linking to libraries with known full paths, the OLD behavior for this
policy will add the linker search paths even though they are not needed
for their own libraries. When this policy is set to OLD, CMake will
produce a link line such as
... -L/path/to /path/to/libA.so -lB ...
which will allow library B to be found as it was previously. When this
policy is set to NEW, CMake will produce a link line such as
... /path/to/libA.so -lB ...
which more accurately matches what the project specified.
The setting for this policy used when generating the link line is that
in effect when the target is created by an add_executable or
add_library command. For the example described above, the code
cmake_policy(SET CMP0003 OLD) # or cmake_policy(VERSION 2.4)
add_executable(myexe myexe.c)
target_link_libraries(myexe /path/to/libA.so B)
will work and suppress the warning for this policy. It may also be
updated to work with the corrected linking approach:
cmake_policy(SET CMP0003 NEW) # or cmake_policy(VERSION 2.6)
link_directories(/path/to) # needed to find library B
add_executable(myexe myexe.c)
target_link_libraries(myexe /path/to/libA.so B)
Even better, library B may be specified with a full path:
add_executable(myexe myexe.c)
target_link_libraries(myexe /path/to/libA.so /path/to/libB.so)
When all items on the link line have known paths CMake does not check
this policy so it has no effect.
Note that the warning for this policy will be issued for at most one
target. This avoids flooding users with messages for every target when
setting the policy once will probably fix all targets.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0002
Logical target names must be globally unique.
Targets names created with add_executable(), add_library(), or
add_custom_target() are logical build target names. Logical target
names must be globally unique because:
- Unique names may be referenced unambiguously both in CMake
code and on make tool command lines.
- Logical names are used by Xcode and VS IDE generators
to produce meaningful project names for the targets.
The logical name of executable and library targets does not have to
correspond to the physical file names built. Consider using the
OUTPUT_NAME target property to create two targets with the same
physical name while keeping logical names distinct. Custom targets
must simply have globally unique names (unless one uses the global
property ALLOW_DUPLICATE_CUSTOM_TARGETS with a Makefiles generator).
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0001
CMAKE_BACKWARDS_COMPATIBILITY should no longer be used.
The behavior is to check CMAKE_BACKWARDS_COMPATIBILITY and present it
to the user. The NEW behavior is to ignore
CMAKE_BACKWARDS_COMPATIBILITY completely.
In CMake 2.4 and below the variable CMAKE_BACKWARDS_COMPATIBILITY was
used to request compatibility with earlier versions of CMake. In CMake
2.6 and above all compatibility issues are handled by policies and the
cmake_policy() command. However, CMake must still check
CMAKE_BACKWARDS_COMPATIBILITY for projects written for CMake 2.4 and
below.
This policy was introduced in CMake version 2.6.0. It may be set by
cmake_policy() or cmake_minimum_required(). If it is not set, CMake
warns, and uses OLD behavior.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
CMP0000
A minimum required CMake version must be specified.
CMake requires that projects specify the version of CMake to which they
have been written. This policy has been put in place so users trying
to build the project may be told when they need to update their CMake.
Specifying a version also helps the project build with CMake versions
newer than that specified. Use the cmake_minimum_required() command at
the top of your main CMakeLists.txt file:
cmake_minimum_required(VERSION <major>.<minor>)
where <major>.<minor> is the version of CMake you want to support (such
as 3.14). The command will ensure that at least the given version of
CMake is running and help newer versions be compatible with the
project. See documentation of cmake_minimum_required() for details.
Note that the command invocation must appear in the CMakeLists.txt file
itself; a call in an included file is not sufficient. However, the
cmake_policy() command may be called to set policy CMP0000 to OLD or
NEW behavior explicitly. The OLD behavior is to silently ignore the
missing invocation. The NEW behavior is to issue an error instead of a
warning. An included file may set CMP0000 explicitly to affect how
this policy is enforced for the main CMakeLists.txt file.
This policy was introduced in CMake version 2.6.0.
NOTE:
The OLD behavior of a policy is deprecated by definition and may be
removed in a future version of CMake.
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3.31.2 December 20, 2024 cmake-policies(7)
cmake 3.31.2 - Generated Sat Dec 21 08:46:09 CST 2024