From d2cb36861f3ad9423bfe1ca7979b33ddf9925a88 Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 14:17:20 +1000 Subject: Help: Fix cross-references in genex manual that linked to wrong genexes --- Help/manual/cmake-generator-expressions.7.rst | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 25e581a..9649e62 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -364,8 +364,6 @@ Variable Queries :manual:`cmake-compile-features(7)` manual for information on compile features and a list of supported compilers. -.. _`Boolean COMPILE_LANGUAGE Generator Expression`: - .. genex:: $ .. versionadded:: 3.15 @@ -405,6 +403,8 @@ Variable Queries $<$,$>:COMPILING_C_WITH_CLANG> ) +.. _`Boolean COMPILE_LANGUAGE Generator Expression`: + .. genex:: $ .. versionadded:: 3.3 @@ -451,8 +451,6 @@ Variable Queries add_executable(myapp main.cpp) target_link_libraries(myapp myapp_c myapp_cxx) -.. _`Boolean LINK_LANGUAGE Generator Expression`: - .. genex:: $ .. versionadded:: 3.18 @@ -495,6 +493,8 @@ Variable Queries ``$`` for constraints about the usage of this generator expression. +.. _`Boolean LINK_LANGUAGE Generator Expression`: + .. genex:: $ .. versionadded:: 3.18 -- cgit v0.12 From 2b102438f811fabb4b64feeb1389d925371e33fe Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 15:59:15 +1000 Subject: Help: Boolean genex conditions must evaluate to 1 or 0 --- Help/manual/cmake-generator-expressions.7.rst | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 9649e62..b546a46 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -60,18 +60,21 @@ Logical Operators .. genex:: $ - where ``conditions`` is a comma-separated list of boolean expressions. - Evaluates to ``1`` if all conditions are ``1``. - Otherwise evaluates to ``0``. + where ``conditions`` is a comma-separated list of boolean expressions, + all of which must evaluate to either ``1`` or ``0``. The whole expression + evaluates to ``1`` if all conditions are ``1``. If any condition is ``0``, + the whole expression evaluates to ``0``. .. genex:: $ where ``conditions`` is a comma-separated list of boolean expressions. - Evaluates to ``1`` if at least one of the conditions is ``1``. - Otherwise evaluates to ``0``. + all of which must evaluate to either ``1`` or ``0``. The whole expression + evaluates to ``1`` if at least one of the ``conditions`` is ``1``. If all + ``conditions`` evaluate to ``0``, the whole expression evaluates to ``0``. .. genex:: $ + ``condition`` must be ``0`` or ``1``. The result of the expression is ``0`` if ``condition`` is ``1``, else ``1``. String Comparisons -- cgit v0.12 From c57c3dbbec3848a0e0a682f406b78b7176bf20d4 Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 16:04:10 +1000 Subject: Help: Genex manual typo, grammar, formatting, wording fixes --- Help/manual/cmake-generator-expressions.7.rst | 70 +++++++++++++-------------- 1 file changed, 35 insertions(+), 35 deletions(-) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index b546a46..34df28f 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -99,8 +99,8 @@ String Comparisons .. versionadded:: 3.12 - ``1`` if ``string`` is member of the semicolon-separated ``list``, else ``0``. - Uses case-sensitive comparisons. + ``1`` if ``string`` is an item in the semicolon-separated ``list``, else ``0``. + It uses case-sensitive comparisons. Version Comparisons ------------------- @@ -227,21 +227,21 @@ Variable Queries .. genex:: $ where ``platform_ids`` is a comma-separated list. - ``1`` if the CMake's platform id matches any one of the entries in + ``1`` if CMake's platform id matches any one of the entries in ``platform_ids``, otherwise ``0``. See also the :variable:`CMAKE_SYSTEM_NAME` variable. .. genex:: $ where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the C compiler matches any one + ``1`` if CMake's compiler id of the C compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the CXX compiler matches any one + ``1`` if CMake's compiler id of the CXX compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -250,7 +250,7 @@ Variable Queries .. versionadded:: 3.15 where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the CUDA compiler matches any one + ``1`` if CMake's compiler id of the CUDA compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -259,7 +259,7 @@ Variable Queries .. versionadded:: 3.16 where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the Objective-C compiler matches any one + ``1`` if CMake's compiler id of the Objective-C compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -268,14 +268,14 @@ Variable Queries .. versionadded:: 3.16 where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the Objective-C++ compiler matches any one + ``1`` if CMake's compiler id of the Objective-C++ compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the Fortran compiler matches any one + ``1`` if CMake's compiler id of the Fortran compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -284,7 +284,7 @@ Variable Queries .. versionadded:: 3.21 where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the HIP compiler matches any one + ``1`` if CMake's compiler id of the HIP compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -293,7 +293,7 @@ Variable Queries .. versionadded:: 3.19 where ``compiler_ids`` is a comma-separated list. - ``1`` if the CMake's compiler id of the ISPC compiler matches any one + ``1`` if CMake's compiler id of the ISPC compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -358,7 +358,7 @@ Variable Queries .. versionadded:: 3.1 - where ``features`` is a comma-spearated list. + where ``features`` is a comma-separated list. Evaluates to ``1`` if all of the ``features`` are available for the 'head' target, and ``0`` otherwise. If this expression is used while evaluating the link implementation of a target and if any dependency transitively @@ -372,7 +372,7 @@ Variable Queries .. versionadded:: 3.15 ``1`` when the language used for compilation unit matches ``language`` and - the CMake's compiler id of the language compiler matches any one of the + CMake's compiler id of the ``language`` compiler matches any one of the entries in ``compiler_ids``, otherwise ``0``. This expression is a short form for the combination of ``$`` and ``$``. This expression may be used to specify @@ -415,7 +415,7 @@ Variable Queries ``1`` when the language used for compilation unit matches any of the entries in ``languages``, otherwise ``0``. This expression may be used to specify compile options, compile definitions, and include directories for source files of a - particular language in a target. For example: + files of a particular language in a target. For example: .. code-block:: cmake @@ -512,7 +512,7 @@ Variable Queries add_library(api_C ...) add_library(api_CXX ...) add_library(api INTERFACE) - target_link_options(api INTERFACE $<$:-opt_c> + target_link_options(api INTERFACE $<$:-opt_c> $<$:-opt_cxx>) target_link_libraries(api INTERFACE $<$:api_C> $<$:api_CXX>) @@ -898,50 +898,50 @@ Variable Queries .. genex:: $ - The CMake's compiler id of the C compiler used. + CMake's compiler id of the C compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ - The CMake's compiler id of the CXX compiler used. + CMake's compiler id of the CXX compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ - The CMake's compiler id of the CUDA compiler used. + CMake's compiler id of the CUDA compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ .. versionadded:: 3.16 - The CMake's compiler id of the OBJC compiler used. + CMake's compiler id of the OBJC compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ .. versionadded:: 3.16 - The CMake's compiler id of the OBJCXX compiler used. + CMake's compiler id of the OBJCXX compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ - The CMake's compiler id of the Fortran compiler used. + CMake's compiler id of the Fortran compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ .. versionadded:: 3.21 - The CMake's compiler id of the HIP compiler used. + CMake's compiler id of the HIP compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ .. versionadded:: 3.19 - The CMake's compiler id of the ISPC compiler used. + CMake's compiler id of the ISPC compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. .. genex:: $ @@ -1006,7 +1006,7 @@ Variable Queries .. versionadded:: 3.18 - The link language of target when evaluating link options. + The link language of the target when evaluating link options. See :ref:`the related boolean expression ` ``$`` for notes about the portability of this generator expression. @@ -1297,8 +1297,8 @@ which is just the string ``tgt``. List of DLLs that the target depends on at runtime. This is determined by the locations of all the ``SHARED`` targets in the target's transitive dependencies. Using this generator expression on targets other than - executables, ``SHARED`` libraries, and ``MODULE`` libraries is an error. On - non-DLL platforms, it evaluates to an empty string. + executables, ``SHARED`` libraries, and ``MODULE`` libraries is an error. + **On non-DLL platforms, this expression always evaluates to an empty string**. This generator expression can be used to copy all of the DLLs that a target depends on into its output directory in a ``POST_BUILD`` custom command. For @@ -1338,7 +1338,7 @@ Output-Related Expressions Marks ``...`` as being the name of a target. This is required if exporting targets to multiple dependent export sets. The ``...`` must be a literal - name of a target- it may not contain generator expressions. + name of a target, it may not contain generator expressions. .. genex:: $ @@ -1613,8 +1613,8 @@ Output-Related Expressions .. genex:: $ - Content of ``...`` when the property is exported using :command:`install(EXPORT)`, - and empty otherwise. + Content of ``...`` when the property is exported using + :command:`install(EXPORT)`, and empty otherwise. .. genex:: $ @@ -1673,18 +1673,18 @@ Debugging Since generator expressions are evaluated during generation of the buildsystem, and not during processing of ``CMakeLists.txt`` files, it is not possible to -inspect their result with the :command:`message()` command. - -One possible way to generate debug messages is to add a custom target, +inspect their result with the :command:`message()` command. One possible way +to generate debug messages is to add a custom target: .. code-block:: cmake add_custom_target(genexdebug COMMAND ${CMAKE_COMMAND} -E echo "$<...>") -The shell command ``make genexdebug`` (invoked after execution of ``cmake``) -would then print the result of ``$<...>``. +After running ``cmake``, you can then build the ``genexdebug`` target to print +the result of the ``$<...>`` expression (i.e. run the command +``cmake --build ... --target genexdebug``). -Another way is to write debug messages to a file: +Another way is to write debug messages to a file with :command:`file(GENERATE)`: .. code-block:: cmake -- cgit v0.12 From 22f8a626c3e5898e2f15aa03d04957eb49804a37 Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 17:25:23 +1000 Subject: Help: Add missing versionadded for CUDA genexes --- Help/manual/cmake-generator-expressions.7.rst | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 34df28f..8d98ff4 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -908,6 +908,8 @@ Variable Queries .. genex:: $ + .. versionadded:: 3.15 + CMake's compiler id of the CUDA compiler used. See also the :variable:`CMAKE__COMPILER_ID` variable. @@ -956,6 +958,8 @@ Variable Queries .. genex:: $ + .. versionadded:: 3.15 + The version of the CUDA compiler used. See also the :variable:`CMAKE__COMPILER_VERSION` variable. -- cgit v0.12 From 3666486c28e4a4f97b6628f6c7f5b72afcdeaec1 Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 16:37:04 +1000 Subject: Help: Move reference content to its own section at end of genex manual This involves moving the Debugging section up to just after the introduction. The content of that section is unchanged. The reference section then follows, and since it is a dedicated section, all existing sections thereunder were demoted one level. Move the note about deviating from the usual CMake docs convention of using angle brackets around placeholders out of the Introduction and to the start of the reference section. No placeholders are used before that point, so that content no longer belongs in the introduction. Apply some minor wording cleanup to the content in the Introduction that remained. --- Help/manual/cmake-generator-expressions.7.rst | 102 +++++++++++++------------- 1 file changed, 53 insertions(+), 49 deletions(-) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 8d98ff4..18147b3 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -11,31 +11,57 @@ Introduction ============ Generator expressions are evaluated during build system generation to produce -information specific to each build configuration. +information specific to each build configuration. They have the form +``$<...>``. Generator expressions are allowed in the context of many target properties, such as :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INCLUDE_DIRECTORIES`, :prop_tgt:`COMPILE_DEFINITIONS` and others. They may also be used when using commands to populate those properties, such as :command:`target_link_libraries`, :command:`target_include_directories`, :command:`target_compile_definitions` -and others. +and others. They enable conditional linking, conditional definitions used when +compiling, conditional include directories, and more. The conditions may be +based on the build configuration, target properties, platform information, +or any other queryable information. -They enable conditional linking, conditional definitions used when compiling, -conditional include directories, and more. The conditions may be based on -the build configuration, target properties, platform information or any other -queryable information. +Generator expressions can be nested, as shown in most of the examples below. -Generator expressions have the form ``$<...>``. To avoid confusion, this page -deviates from most of the CMake documentation in that it omits angular brackets -``<...>`` around placeholders like ``condition``, ``string``, ``target``, -among others. +Debugging +========= -Generator expressions can be nested, as shown in most of the examples below. +Since generator expressions are evaluated during generation of the buildsystem, +and not during processing of ``CMakeLists.txt`` files, it is not possible to +inspect their result with the :command:`message()` command. One possible way +to generate debug messages is to add a custom target: + +.. code-block:: cmake + + add_custom_target(genexdebug COMMAND ${CMAKE_COMMAND} -E echo "$<...>") + +After running ``cmake``, you can then build the ``genexdebug`` target to print +the result of the ``$<...>`` expression (i.e. run the command +``cmake --build ... --target genexdebug``). + +Another way is to write debug messages to a file with :command:`file(GENERATE)`: + +.. code-block:: cmake + + file(GENERATE OUTPUT filename CONTENT "$<...>") + +Generator Expression Reference +============================== + +.. note:: + + This reference deviates from most of the CMake documentation in that it + omits angular brackets ``<...>`` around placeholders like ``condition``, + ``string``, ``target``, etc. This is to prevent an opportunity for those + placeholders to be misinterpreted as generator expressions. .. _`Boolean Generator Expressions`: Boolean Generator Expressions -============================= +----------------------------- Boolean expressions evaluate to either ``0`` or ``1``. They are typically used to construct the condition in a :ref:`conditional @@ -44,7 +70,7 @@ generator expression`. Available boolean expressions are: Logical Operators ------------------ +^^^^^^^^^^^^^^^^^ .. genex:: $ @@ -78,7 +104,7 @@ Logical Operators ``0`` if ``condition`` is ``1``, else ``1``. String Comparisons ------------------- +^^^^^^^^^^^^^^^^^^ .. genex:: $ @@ -103,7 +129,7 @@ String Comparisons It uses case-sensitive comparisons. Version Comparisons -------------------- +^^^^^^^^^^^^^^^^^^^ .. genex:: $ @@ -130,7 +156,7 @@ Version Comparisons ``1`` if ``v1`` is a version greater than or equal to ``v2``, else ``0``. Path Comparisons ----------------- +^^^^^^^^^^^^^^^^ .. genex:: $ @@ -145,7 +171,7 @@ Path Comparisons .. _GenEx Path Queries: Path Queries ------------- +^^^^^^^^^^^^ The ``$`` generator expression offers the same capabilities as the :command:`cmake_path` command, for the :ref:`Query ` options. @@ -208,7 +234,7 @@ The ``$`` generator expression can also be used for path :ref:`normalized ` before the check. Variable Queries ----------------- +^^^^^^^^^^^^^^^^ .. genex:: $ @@ -564,7 +590,7 @@ Variable Queries correctly add target ``libother`` as link dependency. String-Valued Generator Expressions -=================================== +----------------------------------- These expressions expand to some string. For example, @@ -609,7 +635,7 @@ introduce a helper variable to keep the code readable: The following string-valued generator expressions are available: Escaped Characters ------------------- +^^^^^^^^^^^^^^^^^^ String literals to escape the special meaning a character would otherwise have: @@ -628,7 +654,7 @@ String literals to escape the special meaning a character would otherwise have: .. _`Conditional Generator Expressions`: Conditional Expressions ------------------------ +^^^^^^^^^^^^^^^^^^^^^^^ Conditional generator expressions depend on a boolean condition that must be ``0`` or ``1``. @@ -658,7 +684,7 @@ otherwise expands to the empty string. .. _`String Transforming Generator Expressions`: String Transformations ----------------------- +^^^^^^^^^^^^^^^^^^^^^^ .. genex:: $ @@ -736,7 +762,7 @@ String Transformations .. _GenEx Path Decomposition: Path Decomposition ------------------- +^^^^^^^^^^^^^^^^^^ The ``$`` generator expression offers the same capabilities as the :command:`cmake_path` command, for the @@ -775,7 +801,7 @@ The ``$`` generator expression can also be used for path .. _GenEx Path Transformations: Path Transformations --------------------- +^^^^^^^^^^^^^^^^^^^^ The ``$`` generator expression offers the same capabilities as the :command:`cmake_path` command, for the @@ -881,7 +907,7 @@ The ``$`` generator expression can also be used for path See :ref:`cmake_path(ABSOLUTE_PATH) ` for more details. Variable Queries ----------------- +^^^^^^^^^^^^^^^^ .. genex:: $ @@ -1024,7 +1050,7 @@ Variable Queries .. _`Target-Dependent Queries`: Target-Dependent Queries ------------------------- +^^^^^^^^^^^^^^^^^^^^^^^^ These queries refer to a target ``tgt``. This can be any runtime artifact, namely: @@ -1336,7 +1362,7 @@ which is just the string ``tgt``. :command:`install(RUNTIME_DEPENDENCY_SET)`, and empty otherwise. Output-Related Expressions --------------------------- +^^^^^^^^^^^^^^^^^^^^^^^^^^ .. genex:: $ @@ -1671,25 +1697,3 @@ Output-Related Expressions With the :generator:`Ninja Multi-Config` generator, generator expressions in ``...`` are evaluated using the custom command's "command config". With other generators, the content of ``...`` is evaluated normally. - -Debugging -========= - -Since generator expressions are evaluated during generation of the buildsystem, -and not during processing of ``CMakeLists.txt`` files, it is not possible to -inspect their result with the :command:`message()` command. One possible way -to generate debug messages is to add a custom target: - -.. code-block:: cmake - - add_custom_target(genexdebug COMMAND ${CMAKE_COMMAND} -E echo "$<...>") - -After running ``cmake``, you can then build the ``genexdebug`` target to print -the result of the ``$<...>`` expression (i.e. run the command -``cmake --build ... --target genexdebug``). - -Another way is to write debug messages to a file with :command:`file(GENERATE)`: - -.. code-block:: cmake - - file(GENERATE OUTPUT filename CONTENT "$<...>") -- cgit v0.12 From 044c22e12129c035b2c8750c61de3e02afa9e5e4 Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 17:04:02 +1000 Subject: Help: Restructure reference sections of genex manual As part of the general restructuring, also move the notes of a more introductory nature out of what was the "String-Valued Generator Expressions" section and up to the dedicated Introduction. This gives the reader a bit more of a foundation before they get to the heavier detail of the reference section. --- Help/manual/cmake-generator-expressions.7.rst | 2116 ++++++++++++------------- 1 file changed, 1055 insertions(+), 1061 deletions(-) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 18147b3..357a20c 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -12,7 +12,14 @@ Introduction Generator expressions are evaluated during build system generation to produce information specific to each build configuration. They have the form -``$<...>``. +``$<...>``. For example: + +.. code-block:: cmake + + target_include_directories(tgt PRIVATE /opt/include/$) + +This would expand to ``/opt/include/GNU``, ``/opt/include/Clang``, etc. +depending on the C++ compiler used. Generator expressions are allowed in the context of many target properties, such as :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INCLUDE_DIRECTORIES`, @@ -24,7 +31,17 @@ compiling, conditional include directories, and more. The conditions may be based on the build configuration, target properties, platform information, or any other queryable information. -Generator expressions can be nested, as shown in most of the examples below. +Generator expressions can be nested: + +.. code-block:: cmake + + target_compile_definitions(tgt PRIVATE + $<$,4.2.0>:OLD_COMPILER> + ) + +The above would expand to ``OLD_COMPILER`` if the +:variable:`CMAKE_CXX_COMPILER_VERSION _COMPILER_VERSION>` is less +than 4.2.0. Debugging ========= @@ -58,19 +75,38 @@ Generator Expression Reference ``string``, ``target``, etc. This is to prevent an opportunity for those placeholders to be misinterpreted as generator expressions. -.. _`Boolean Generator Expressions`: +.. _`Conditional Generator Expressions`: -Boolean Generator Expressions ------------------------------ +Conditional Expressions +----------------------- + +A fundamental category of generator expressions relates to conditional logic. +Two forms of conditional generator expressions are supported: -Boolean expressions evaluate to either ``0`` or ``1``. -They are typically used to construct the condition in a :ref:`conditional -generator expression`. +.. genex:: $ -Available boolean expressions are: + Evaluates to ``true_string`` if ``condition`` is ``1``, or an empty string + if ``condition`` evaluates to ``0``. Any other value for ``condition`` + results in an error. -Logical Operators -^^^^^^^^^^^^^^^^^ +.. genex:: $ + + .. versionadded:: 3.8 + + Evaluates to ``true_string`` if ``condition`` is ``1``, or ``false_string`` + if ``condition`` is ``0``. Any other value for ``condition`` results in an + error. + +Typically, the ``condition`` is itself a generator expression. For instance, +the following expression expands to ``DEBUG_MODE`` when the ``Debug`` +configuration is used, and the empty string for all other configurations: + +.. code-block:: cmake + + $<$:DEBUG_MODE> + +Boolean-like ``condition`` values other than ``1`` or ``0`` can be handled +by wrapping them with the ``$`` generator expression: .. genex:: $ @@ -84,6 +120,21 @@ Logical Operators Otherwise evaluates to ``1``. +The ``$`` generator expression is often used when a ``condition`` +is provided by a CMake variable: + +.. code-block:: cmake + + $<$:-DENABLE_SOME_FEATURE> + + +.. _`Boolean Generator Expressions`: + +Logical Operators +----------------- + +The common boolean logic operators are supported: + .. genex:: $ where ``conditions`` is a comma-separated list of boolean expressions, @@ -103,6 +154,16 @@ Logical Operators ``condition`` must be ``0`` or ``1``. The result of the expression is ``0`` if ``condition`` is ``1``, else ``1``. +.. _`Comparison Expressions`: + +Primary Comparison Expressions +------------------------------ + +CMake supports a variety of generator expressions that compare things. +This section covers the primary and most widely used comparison types. +Other more specific comparison types are documented in their own separate +sections further below. + String Comparisons ^^^^^^^^^^^^^^^^^^ @@ -111,23 +172,17 @@ String Comparisons ``1`` if ``string1`` and ``string2`` are equal, else ``0``. The comparison is case-sensitive. For a case-insensitive comparison, combine with a :ref:`string transforming generator expression - `, + `. For example, the following + evaluates to ``1`` if ``${foo}`` is any of ``BAR``, ``Bar``, ``bar``, etc. .. code-block:: cmake - $,"BAR"> # "1" if ${foo} is any of "BAR", "Bar", "bar", ... + $,BAR> .. genex:: $ ``1`` if ``value1`` and ``value2`` are numerically equal, else ``0``. -.. genex:: $ - - .. versionadded:: 3.12 - - ``1`` if ``string`` is an item in the semicolon-separated ``list``, else ``0``. - It uses case-sensitive comparisons. - Version Comparisons ^^^^^^^^^^^^^^^^^^^ @@ -155,6 +210,67 @@ Version Comparisons ``1`` if ``v1`` is a version greater than or equal to ``v2``, else ``0``. +.. _`String Transforming Generator Expressions`: + +String Transformations +---------------------- + +.. genex:: $ + + Content of ``string`` converted to lower case. + +.. genex:: $ + + Content of ``string`` converted to upper case. + +.. genex:: $ + + Content of ``...`` converted to a C identifier. The conversion follows the + same behavior as :command:`string(MAKE_C_IDENTIFIER)`. + +List Expressions +---------------- + +.. genex:: $ + + .. versionadded:: 3.12 + + ``1`` if ``string`` is an item in the semicolon-separated ``list``, else ``0``. + It uses case-sensitive comparisons. + +.. genex:: $ + + Joins the list with the content of ``string`` inserted between each item. + +.. genex:: $ + + .. versionadded:: 3.15 + + Removes duplicated items in the given ``list``. The relative order of items + is preserved, but if duplicates are encountered, only the first instance is + preserved. + +.. genex:: $ + + .. versionadded:: 3.15 + + Includes or removes items from ``list`` that match the regular expression + ``regex``. + +Path Expressions +---------------- + +Most of the expressions in this section are closely associated with the +:command:`cmake_path` command, providing the same capabilities, but in +the form of a generator expression. + +For all generator expressions in this section, paths are expected to be in +cmake-style format. The :ref:`$\ ` +generator expression can be used to convert a native path to a cmake-style +one. + +.. _GenEx Path Comparisons: + Path Comparisons ^^^^^^^^^^^^^^^^ @@ -173,16 +289,9 @@ Path Comparisons Path Queries ^^^^^^^^^^^^ -The ``$`` generator expression offers the same capabilities as the -:command:`cmake_path` command, for the :ref:`Query ` options. - -For all ``$`` generator expressions, paths are expected in cmake-style -format. The :ref:`$\ ` generator -expression can be used to convert a native path to a cmake-style one. - -The ``$`` generator expression can also be used for path -:ref:`Decomposition ` and -:ref:`Transformations `. +These expressions provide the generation-time capabilities equivalent to the +:ref:`Query ` options of the :command:`cmake_path` command. +All paths are expected to be in cmake-style format. .. genex:: $ @@ -228,1083 +337,967 @@ The ``$`` generator expression can also be used for path .. versionadded:: 3.24 - Returns ``1`` if ``path`` is the prefix of ``input``,``0`` otherwise. + Returns ``1`` if ``path`` is the prefix of ``input``, ``0`` otherwise. When the ``NORMALIZE`` option is specified, ``path`` and ``input`` are :ref:`normalized ` before the check. -Variable Queries -^^^^^^^^^^^^^^^^ +.. _GenEx Path Decomposition: -.. genex:: $ +Path Decomposition +^^^^^^^^^^^^^^^^^^ - .. versionadded:: 3.12 +These expressions provide the generation-time capabilities equivalent to the +:ref:`Decomposition ` options of the :command:`cmake_path` +command. All paths are expected to be in cmake-style format. - ``1`` if ``target`` exists, else ``0``. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.24 - ``1`` if config is any one of the entries in comma-separated list - ``cfgs``, else ``0``. This is a case-insensitive comparison. The mapping in - :prop_tgt:`MAP_IMPORTED_CONFIG_` is also considered by this - expression when it is evaluated on a property on an :prop_tgt:`IMPORTED` - target. + The following operations retrieve a different component or group of + components from a path. See :ref:`Path Structure And Terminology` for the + meaning of each path component. -.. genex:: $ + :: - where ``platform_ids`` is a comma-separated list. - ``1`` if CMake's platform id matches any one of the entries in - ``platform_ids``, otherwise ``0``. - See also the :variable:`CMAKE_SYSTEM_NAME` variable. + $ + $ + $ + $ + $ + $ + $ + $ -.. genex:: $ + If a requested component is not present in the path, an empty string is + returned. - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the C compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. +.. _GenEx Path Transformations: -.. genex:: $ +Path Transformations +^^^^^^^^^^^^^^^^^^^^ - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the CXX compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. +These expressions provide the generation-time capabilities equivalent to the +:ref:`Modification ` and :ref:`Generation ` +options of the :command:`cmake_path` command. All paths are expected to be +in cmake-style format. -.. genex:: $ +.. _GenEx PATH-CMAKE_PATH: - .. versionadded:: 3.15 +.. genex:: $ - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the CUDA compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. + .. versionadded:: 3.24 -.. genex:: $ + Returns ``path``. If ``path`` is a native path, it is converted into a + cmake-style path with forward-slashes (``/``). On Windows, the long filename + marker is taken into account. - .. versionadded:: 3.16 + When the ``NORMALIZE`` option is specified, the path is :ref:`normalized + ` after the conversion. - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the Objective-C compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.24 - .. versionadded:: 3.16 + Returns all the ``input`` arguments appended to ``path`` using ``/`` as the + ``directory-separator``. Depending on the ``input``, the value of ``path`` + may be discarded. - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the Objective-C++ compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. + See :ref:`cmake_path(APPEND) ` for more details. -.. genex:: $ +.. genex:: $ - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the Fortran compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. + .. versionadded:: 3.24 -.. genex:: $ + Returns ``path`` with filename component (as returned by + ``$``) removed. After removal, any trailing + ``directory-separator`` is left alone, if present. - .. versionadded:: 3.21 + See :ref:`cmake_path(REMOVE_FILENAME) ` for more details. - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the HIP compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.24 - .. versionadded:: 3.19 + Returns ``path`` with the filename component replaced by ``input``. If + ``path`` has no filename component (i.e. ``$`` returns + ``0``), ``path`` is unchanged. - where ``compiler_ids`` is a comma-separated list. - ``1`` if CMake's compiler id of the ISPC compiler matches any one - of the entries in ``compiler_ids``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_ID` variable. + See :ref:`cmake_path(REPLACE_FILENAME) ` for more details. -.. genex:: $ +.. genex:: $ - ``1`` if the version of the C compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + .. versionadded:: 3.24 -.. genex:: $ + Returns ``path`` with the :ref:`extension ` removed, if any. - ``1`` if the version of the CXX compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + See :ref:`cmake_path(REMOVE_EXTENSION) ` for more details. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.15 + .. versionadded:: 3.24 - ``1`` if the version of the CXX compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + Returns ``path`` with the :ref:`extension ` replaced by + ``input``, if any. -.. genex:: $ + See :ref:`cmake_path(REPLACE_EXTENSION) ` for more details. - .. versionadded:: 3.16 +.. genex:: $ - ``1`` if the version of the OBJC compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + .. versionadded:: 3.24 -.. genex:: $ + Returns ``path`` normalized according to the steps described in + :ref:`Normalization`. - .. versionadded:: 3.16 +.. genex:: $ - ``1`` if the version of the OBJCXX compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + .. versionadded:: 3.24 -.. genex:: $ + Returns ``path``, modified to make it relative to the ``base_directory`` + argument. - ``1`` if the version of the Fortran compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + See :ref:`cmake_path(RELATIVE_PATH) ` for more + details. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.21 + .. versionadded:: 3.24 - ``1`` if the version of the HIP compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + Returns ``path`` as absolute. If ``path`` is a relative path + (``$`` returns ``1``), it is evaluated relative to the + given base directory specified by ``base_directory`` argument. -.. genex:: $ + When the ``NORMALIZE`` option is specified, the path is + :ref:`normalized ` after the path computation. - .. versionadded:: 3.19 + See :ref:`cmake_path(ABSOLUTE_PATH) ` for more details. - ``1`` if the version of the ISPC compiler matches ``version``, otherwise ``0``. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. +Shell Paths +^^^^^^^^^^^ -.. genex:: $ +.. genex:: $ - ``1`` if the ``policy`` was NEW when the 'head' target was created, - else ``0``. If the ``policy`` was not set, the warning message for the policy - will be emitted. This generator expression only works for a subset of - policies. + .. versionadded:: 3.4 -.. genex:: $ + Content of ``...`` converted to shell path style. For example, slashes are + converted to backslashes in Windows shells and drive letters are converted + to posix paths in MSYS shells. The ``...`` must be an absolute path. - .. versionadded:: 3.1 + .. versionadded:: 3.14 + The ``...`` may be a :ref:`semicolon-separated list ` + of paths, in which case each path is converted individually and a result + list is generated using the shell path separator (``:`` on POSIX and + ``;`` on Windows). Be sure to enclose the argument containing this genex + in double quotes in CMake source code so that ``;`` does not split arguments. - where ``features`` is a comma-separated list. - Evaluates to ``1`` if all of the ``features`` are available for the 'head' - target, and ``0`` otherwise. If this expression is used while evaluating - the link implementation of a target and if any dependency transitively - increases the required :prop_tgt:`C_STANDARD` or :prop_tgt:`CXX_STANDARD` - for the 'head' target, an error is reported. See the - :manual:`cmake-compile-features(7)` manual for information on - compile features and a list of supported compilers. +Configuration Expressions +------------------------- -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.15 + Configuration name. Use this instead of the deprecated :genex:`CONFIGURATION` + generator expression. - ``1`` when the language used for compilation unit matches ``language`` and - CMake's compiler id of the ``language`` compiler matches any one of the - entries in ``compiler_ids``, otherwise ``0``. This expression is a short form - for the combination of ``$`` and - ``$``. This expression may be used to specify - compile options, compile definitions, and include directories for source files of a - particular language and compiler combination in a target. For example: +.. genex:: $ - .. code-block:: cmake + ``1`` if config is any one of the entries in comma-separated list + ``cfgs``, else ``0``. This is a case-insensitive comparison. The mapping in + :prop_tgt:`MAP_IMPORTED_CONFIG_` is also considered by this + expression when it is evaluated on a property of an :prop_tgt:`IMPORTED` + target. - add_executable(myapp main.cpp foo.c bar.cpp zot.cu) - target_compile_definitions(myapp - PRIVATE $<$:COMPILING_CXX_WITH_CLANG> - $<$:COMPILING_CXX_WITH_INTEL> - $<$:COMPILING_C_WITH_CLANG> - ) +.. genex:: $ - This specifies the use of different compile definitions based on both - the compiler id and compilation language. This example will have a - ``COMPILING_CXX_WITH_CLANG`` compile definition when Clang is the CXX - compiler, and ``COMPILING_CXX_WITH_INTEL`` when Intel is the CXX compiler. - Likewise when the C compiler is Clang it will only see the ``COMPILING_C_WITH_CLANG`` - definition. + .. versionadded:: 3.20 - Without the ``COMPILE_LANG_AND_ID`` generator expression the same logic - would be expressed as: + Only valid in :command:`add_custom_command` and :command:`add_custom_target` + as the outer-most generator expression in an argument. + With the :generator:`Ninja Multi-Config` generator, generator expressions + in ``...`` are evaluated using the custom command's "output config". + With other generators, the content of ``...`` is evaluated normally. - .. code-block:: cmake +.. genex:: $ - target_compile_definitions(myapp - PRIVATE $<$,$>:COMPILING_CXX_WITH_CLANG> - $<$,$>:COMPILING_CXX_WITH_INTEL> - $<$,$>:COMPILING_C_WITH_CLANG> - ) + .. versionadded:: 3.20 -.. _`Boolean COMPILE_LANGUAGE Generator Expression`: + Only valid in :command:`add_custom_command` and :command:`add_custom_target` + as the outer-most generator expression in an argument. + With the :generator:`Ninja Multi-Config` generator, generator expressions + in ``...`` are evaluated using the custom command's "command config". + With other generators, the content of ``...`` is evaluated normally. -.. genex:: $ +Toolchain And Language Expressions +---------------------------------- - .. versionadded:: 3.3 +Platform +^^^^^^^^ - ``1`` when the language used for compilation unit matches any of the entries - in ``languages``, otherwise ``0``. This expression may be used to specify - compile options, compile definitions, and include directories for source files of a - files of a particular language in a target. For example: +.. genex:: $ - .. code-block:: cmake + The current system's CMake platform id. + See also the :variable:`CMAKE_SYSTEM_NAME` variable. - add_executable(myapp main.cpp foo.c bar.cpp zot.cu) - target_compile_options(myapp - PRIVATE $<$:-fno-exceptions> - ) - target_compile_definitions(myapp - PRIVATE $<$:COMPILING_CXX> - $<$:COMPILING_CUDA> - ) - target_include_directories(myapp - PRIVATE $<$:/opt/foo/headers> - ) +.. genex:: $ - This specifies the use of the ``-fno-exceptions`` compile option, - ``COMPILING_CXX`` compile definition, and ``cxx_headers`` include - directory for C++ only (compiler id checks elided). It also specifies - a ``COMPILING_CUDA`` compile definition for CUDA. + where ``platform_ids`` is a comma-separated list. + ``1`` if CMake's platform id matches any one of the entries in + ``platform_ids``, otherwise ``0``. + See also the :variable:`CMAKE_SYSTEM_NAME` variable. - Note that with :ref:`Visual Studio Generators` and :generator:`Xcode` there - is no way to represent target-wide compile definitions or include directories - separately for ``C`` and ``CXX`` languages. - Also, with :ref:`Visual Studio Generators` there is no way to represent - target-wide flags separately for ``C`` and ``CXX`` languages. Under these - generators, expressions for both C and C++ sources will be evaluated - using ``CXX`` if there are any C++ sources and otherwise using ``C``. - A workaround is to create separate libraries for each source file language - instead: +Compiler Version +^^^^^^^^^^^^^^^^ - .. code-block:: cmake +See also the :variable:`CMAKE__COMPILER_VERSION` variable, which is +closely related to the expressions in this sub-section. - add_library(myapp_c foo.c) - add_library(myapp_cxx bar.cpp) - target_compile_options(myapp_cxx PUBLIC -fno-exceptions) - add_executable(myapp main.cpp) - target_link_libraries(myapp myapp_c myapp_cxx) +.. genex:: $ -.. genex:: $ + The version of the C compiler used. - .. versionadded:: 3.18 +.. genex:: $ - ``1`` when the language used for link step matches ``language`` and the - CMake's compiler id of the language linker matches any one of the entries - in ``compiler_ids``, otherwise ``0``. This expression is a short form for the - combination of ``$`` and - ``$``. This expression may be used to specify - link libraries, link options, link directories and link dependencies of a - particular language and linker combination in a target. For example: + ``1`` if the version of the C compiler matches ``version``, otherwise ``0``. - .. code-block:: cmake +.. genex:: $ - add_library(libC_Clang ...) - add_library(libCXX_Clang ...) - add_library(libC_Intel ...) - add_library(libCXX_Intel ...) + The version of the CXX compiler used. - add_executable(myapp main.c) - if (CXX_CONFIG) - target_sources(myapp PRIVATE file.cxx) - endif() - target_link_libraries(myapp - PRIVATE $<$:libCXX_Clang> - $<$:libC_Clang> - $<$:libCXX_Intel> - $<$:libC_Intel>) +.. genex:: $ - This specifies the use of different link libraries based on both the - compiler id and link language. This example will have target ``libCXX_Clang`` - as link dependency when ``Clang`` or ``AppleClang`` is the ``CXX`` - linker, and ``libCXX_Intel`` when ``Intel`` is the ``CXX`` linker. - Likewise when the ``C`` linker is ``Clang`` or ``AppleClang``, target - ``libC_Clang`` will be added as link dependency and ``libC_Intel`` when - ``Intel`` is the ``C`` linker. + ``1`` if the version of the CXX compiler matches ``version``, otherwise ``0``. - See :ref:`the note related to - ` - ``$`` for constraints about the usage of this - generator expression. +.. genex:: $ -.. _`Boolean LINK_LANGUAGE Generator Expression`: + .. versionadded:: 3.15 -.. genex:: $ + The version of the CUDA compiler used. - .. versionadded:: 3.18 +.. genex:: $ - ``1`` when the language used for link step matches any of the entries - in ``languages``, otherwise ``0``. This expression may be used to specify - link libraries, link options, link directories and link dependencies of a - particular language in a target. For example: + .. versionadded:: 3.15 - .. code-block:: cmake + ``1`` if the version of the CXX compiler matches ``version``, otherwise ``0``. - add_library(api_C ...) - add_library(api_CXX ...) - add_library(api INTERFACE) - target_link_options(api INTERFACE $<$:-opt_c> - $<$:-opt_cxx>) - target_link_libraries(api INTERFACE $<$:api_C> - $<$:api_CXX>) +.. genex:: $ - add_executable(myapp1 main.c) - target_link_options(myapp1 PRIVATE api) + .. versionadded:: 3.16 - add_executable(myapp2 main.cpp) - target_link_options(myapp2 PRIVATE api) + The version of the OBJC compiler used. - This specifies to use the ``api`` target for linking targets ``myapp1`` and - ``myapp2``. In practice, ``myapp1`` will link with target ``api_C`` and - option ``-opt_c`` because it will use ``C`` as link language. And ``myapp2`` - will link with ``api_CXX`` and option ``-opt_cxx`` because ``CXX`` will be - the link language. +.. genex:: $ - .. _`Constraints LINK_LANGUAGE Generator Expression`: + .. versionadded:: 3.16 - .. note:: + ``1`` if the version of the OBJC compiler matches ``version``, otherwise ``0``. - To determine the link language of a target, it is required to collect, - transitively, all the targets which will be linked to it. So, for link - libraries properties, a double evaluation will be done. During the first - evaluation, ``$`` expressions will always return ``0``. - The link language computed after this first pass will be used to do the - second pass. To avoid inconsistency, it is required that the second pass - do not change the link language. Moreover, to avoid unexpected - side-effects, it is required to specify complete entities as part of the - ``$`` expression. For example: +.. genex:: $ - .. code-block:: cmake + .. versionadded:: 3.16 - add_library(lib STATIC file.cxx) - add_library(libother STATIC file.c) + The version of the OBJCXX compiler used. - # bad usage - add_executable(myapp1 main.c) - target_link_libraries(myapp1 PRIVATE lib$<$:other>) +.. genex:: $ - # correct usage - add_executable(myapp2 main.c) - target_link_libraries(myapp2 PRIVATE $<$:libother>) + .. versionadded:: 3.16 - In this example, for ``myapp1``, the first pass will, unexpectedly, - determine that the link language is ``CXX`` because the evaluation of the - generator expression will be an empty string so ``myapp1`` will depends on - target ``lib`` which is ``C++``. On the contrary, for ``myapp2``, the first - evaluation will give ``C`` as link language, so the second pass will - correctly add target ``libother`` as link dependency. + ``1`` if the version of the OBJCXX compiler matches ``version``, otherwise ``0``. -String-Valued Generator Expressions ------------------------------------ +.. genex:: $ -These expressions expand to some string. -For example, + The version of the Fortran compiler used. -.. code-block:: cmake +.. genex:: $ - include_directories(/usr/include/$/) + ``1`` if the version of the Fortran compiler matches ``version``, otherwise ``0``. -expands to ``/usr/include/GNU/`` or ``/usr/include/Clang/`` etc, depending on -the compiler identifier. +.. genex:: $ -String-valued expressions may also be combined with other expressions. -Here an example for a string-valued expression within a boolean expressions -within a conditional expression: + .. versionadded:: 3.21 -.. code-block:: cmake + The version of the HIP compiler used. - $<$,4.2.0>:OLD_COMPILER> +.. genex:: $ -expands to ``OLD_COMPILER`` if the -:variable:`CMAKE_CXX_COMPILER_VERSION _COMPILER_VERSION>` is less -than 4.2.0. + .. versionadded:: 3.21 -And here two nested string-valued expressions: + ``1`` if the version of the HIP compiler matches ``version``, otherwise ``0``. -.. code-block:: cmake +.. genex:: $ - -I$, -I> + .. versionadded:: 3.19 -generates a string of the entries in the :prop_tgt:`INCLUDE_DIRECTORIES` target -property with each entry preceded by ``-I``. + The version of the ISPC compiler used. -Expanding on the previous example, if one first wants to check if the -``INCLUDE_DIRECTORIES`` property is non-empty, then it is advisable to -introduce a helper variable to keep the code readable: +.. genex:: $ -.. code-block:: cmake + .. versionadded:: 3.19 - set(prop "$") # helper variable - $<$:-I$> + ``1`` if the version of the ISPC compiler matches ``version``, otherwise ``0``. -The following string-valued generator expressions are available: +Compiler Language And ID +^^^^^^^^^^^^^^^^^^^^^^^^ -Escaped Characters -^^^^^^^^^^^^^^^^^^ +See also the :variable:`CMAKE__COMPILER_ID` variable, which is closely +related to most of the expressions in this sub-section. -String literals to escape the special meaning a character would otherwise have: +.. genex:: $ -.. genex:: $ + CMake's compiler id of the C compiler used. - A literal ``>``. Used for example to compare strings that contain a ``>``. +.. genex:: $ -.. genex:: $ + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the C compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. - A literal ``,``. Used for example to compare strings which contain a ``,``. +.. genex:: $ -.. genex:: $ + CMake's compiler id of the CXX compiler used. - A literal ``;``. Used to prevent list expansion on an argument with ``;``. +.. genex:: $ -.. _`Conditional Generator Expressions`: + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the CXX compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. -Conditional Expressions -^^^^^^^^^^^^^^^^^^^^^^^ +.. genex:: $ -Conditional generator expressions depend on a boolean condition -that must be ``0`` or ``1``. + .. versionadded:: 3.15 -.. genex:: $ + CMake's compiler id of the CUDA compiler used. - Evaluates to ``true_string`` if ``condition`` is ``1``. - Otherwise evaluates to the empty string. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.15 - .. versionadded:: 3.8 + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the CUDA compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. - Evaluates to ``true_string`` if ``condition`` is ``1``. - Otherwise evaluates to ``false_string``. +.. genex:: $ -Typically, the ``condition`` is a :ref:`boolean generator expression -`. For instance, + .. versionadded:: 3.16 -.. code-block:: cmake + CMake's compiler id of the OBJC compiler used. - $<$:DEBUG_MODE> +.. genex:: $ -expands to ``DEBUG_MODE`` when the ``Debug`` configuration is used, and -otherwise expands to the empty string. + .. versionadded:: 3.16 -.. _`String Transforming Generator Expressions`: + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the Objective-C compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. -String Transformations -^^^^^^^^^^^^^^^^^^^^^^ +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.16 - Joins the list with the content of ``string``. + CMake's compiler id of the OBJCXX compiler used. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.15 + .. versionadded:: 3.16 - Removes duplicated items in the given ``list``. The relative order of items - is preserved, but if duplicates are encountered, only the first instance is - preserved. + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the Objective-C++ compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.15 + CMake's compiler id of the Fortran compiler used. - Includes or removes items from ``list`` that match the regular expression ``regex``. +.. genex:: $ -.. genex:: $ + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the Fortran compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. - Content of ``string`` converted to lower case. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.21 - Content of ``string`` converted to upper case. + CMake's compiler id of the HIP compiler used. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.12 + .. versionadded:: 3.21 - Content of ``expr`` evaluated as a generator expression in the current - context. This enables consumption of generator expressions whose - evaluation results itself in generator expressions. + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the HIP compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.12 + .. versionadded:: 3.19 - Content of ``expr`` evaluated as a generator expression in the context of - ``tgt`` target. This enables consumption of custom target properties that - themselves contain generator expressions. + CMake's compiler id of the ISPC compiler used. - Having the capability to evaluate generator expressions is very useful when - you want to manage custom properties supporting generator expressions. - For example: +.. genex:: $ - .. code-block:: cmake + .. versionadded:: 3.19 - add_library(foo ...) + where ``compiler_ids`` is a comma-separated list. + ``1`` if CMake's compiler id of the ISPC compiler matches any one + of the entries in ``compiler_ids``, otherwise ``0``. - set_property(TARGET foo PROPERTY - CUSTOM_KEYS $<$:FOO_EXTRA_THINGS> - ) +.. genex:: $ - add_custom_target(printFooKeys - COMMAND ${CMAKE_COMMAND} -E echo $ - ) + .. versionadded:: 3.3 - This naive implementation of the ``printFooKeys`` custom command is wrong - because ``CUSTOM_KEYS`` target property is not evaluated and the content - is passed as is (i.e. ``$<$:FOO_EXTRA_THINGS>``). + The compile language of source files when evaluating compile options. + See :ref:`the related boolean expression + ` + ``$`` + for notes about the portability of this generator expression. - To have the expected result (i.e. ``FOO_EXTRA_THINGS`` if config is - ``Debug``), it is required to evaluate the output of - ``$``: +.. _`Boolean COMPILE_LANGUAGE Generator Expression`: - .. code-block:: cmake +.. genex:: $ - add_custom_target(printFooKeys - COMMAND ${CMAKE_COMMAND} -E - echo $> - ) + .. versionadded:: 3.3 -.. _GenEx Path Decomposition: + ``1`` when the language used for compilation unit matches any of the entries + in ``languages``, otherwise ``0``. This expression may be used to specify + compile options, compile definitions, and include directories for source + files of a particular language in a target. For example: -Path Decomposition -^^^^^^^^^^^^^^^^^^ + .. code-block:: cmake -The ``$`` generator expression offers the same capabilities as the -:command:`cmake_path` command, for the -:ref:`Decomposition ` options. + add_executable(myapp main.cpp foo.c bar.cpp zot.cu) + target_compile_options(myapp + PRIVATE $<$:-fno-exceptions> + ) + target_compile_definitions(myapp + PRIVATE $<$:COMPILING_CXX> + $<$:COMPILING_CUDA> + ) + target_include_directories(myapp + PRIVATE $<$:/opt/foo/headers> + ) -For all ``$`` generator expressions, paths are expected in cmake-style -format. The :ref:`$\ ` generator -expression can be used to convert a native path to a cmake-style one. + This specifies the use of the ``-fno-exceptions`` compile option, + ``COMPILING_CXX`` compile definition, and ``cxx_headers`` include + directory for C++ only (compiler id checks elided). It also specifies + a ``COMPILING_CUDA`` compile definition for CUDA. -The ``$`` generator expression can also be used for path -:ref:`Queries ` and -:ref:`Transformations `. + Note that with :ref:`Visual Studio Generators` and :generator:`Xcode` there + is no way to represent target-wide compile definitions or include directories + separately for ``C`` and ``CXX`` languages. + Also, with :ref:`Visual Studio Generators` there is no way to represent + target-wide flags separately for ``C`` and ``CXX`` languages. Under these + generators, expressions for both C and C++ sources will be evaluated + using ``CXX`` if there are any C++ sources and otherwise using ``C``. + A workaround is to create separate libraries for each source file language + instead: -.. genex:: $ + .. code-block:: cmake - .. versionadded:: 3.24 + add_library(myapp_c foo.c) + add_library(myapp_cxx bar.cpp) + target_compile_options(myapp_cxx PUBLIC -fno-exceptions) + add_executable(myapp main.cpp) + target_link_libraries(myapp myapp_c myapp_cxx) - The following operations retrieve a different component or group of - components from a path. See :ref:`Path Structure And Terminology` for the - meaning of each path component. +.. genex:: $ - :: + .. versionadded:: 3.15 - $ - $ - $ - $ - $ - $ - $ - $ + ``1`` when the language used for compilation unit matches ``language`` and + CMake's compiler id of the ``language`` compiler matches any one of the + entries in ``compiler_ids``, otherwise ``0``. This expression is a short form + for the combination of ``$`` and + ``$``. This expression may be used to specify + compile options, compile definitions, and include directories for source + files of a particular language and compiler combination in a target. + For example: - If a requested component is not present in the path, an empty string is - returned. + .. code-block:: cmake -.. _GenEx Path Transformations: + add_executable(myapp main.cpp foo.c bar.cpp zot.cu) + target_compile_definitions(myapp + PRIVATE $<$:COMPILING_CXX_WITH_CLANG> + $<$:COMPILING_CXX_WITH_INTEL> + $<$:COMPILING_C_WITH_CLANG> + ) -Path Transformations -^^^^^^^^^^^^^^^^^^^^ + This specifies the use of different compile definitions based on both + the compiler id and compilation language. This example will have a + ``COMPILING_CXX_WITH_CLANG`` compile definition when Clang is the CXX + compiler, and ``COMPILING_CXX_WITH_INTEL`` when Intel is the CXX compiler. + Likewise, when the C compiler is Clang, it will only see the + ``COMPILING_C_WITH_CLANG`` definition. -The ``$`` generator expression offers the same capabilities as the -:command:`cmake_path` command, for the -:ref:`Modification ` and -:ref:`Generation ` options. + Without the ``COMPILE_LANG_AND_ID`` generator expression, the same logic + would be expressed as: -For all ``$`` generator expressions, paths are expected in cmake-style -format. The :ref:`$\ ` generator -expression can be used to convert a native path to a cmake-style one. + .. code-block:: cmake -The ``$`` generator expression can also be used for path -:ref:`Queries ` and -:ref:`Decomposition `. + target_compile_definitions(myapp + PRIVATE $<$,$>:COMPILING_CXX_WITH_CLANG> + $<$,$>:COMPILING_CXX_WITH_INTEL> + $<$,$>:COMPILING_C_WITH_CLANG> + ) -.. _GenEx PATH-CMAKE_PATH: +Compile Features +^^^^^^^^^^^^^^^^ -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.24 + .. versionadded:: 3.1 - Returns ``path``. If ``path`` is a native path, it is converted into a - cmake-style path with forward-slashes (``/``). On Windows, the long filename - marker is taken into account. + where ``features`` is a comma-separated list. + Evaluates to ``1`` if all of the ``features`` are available for the 'head' + target, and ``0`` otherwise. If this expression is used while evaluating + the link implementation of a target and if any dependency transitively + increases the required :prop_tgt:`C_STANDARD` or :prop_tgt:`CXX_STANDARD` + for the 'head' target, an error is reported. See the + :manual:`cmake-compile-features(7)` manual for information on + compile features and a list of supported compilers. - When the ``NORMALIZE`` option is specified, the path is :ref:`normalized - ` after the conversion. +Linker Language And ID +^^^^^^^^^^^^^^^^^^^^^^ -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.24 + .. versionadded:: 3.18 - Returns all the ``input`` arguments appended to ``path`` using ``/`` as the - ``directory-separator``. Depending on the ``input``, the value of ``path`` - may be discarded. + The link language of the target when evaluating link options. + See :ref:`the related boolean expression + ` ``$`` + for notes about the portability of this generator expression. - See :ref:`cmake_path(APPEND) ` for more details. + .. note:: -.. genex:: $ + This generator expression is not supported by the link libraries + properties to avoid side-effects due to the double evaluation of + these properties. - .. versionadded:: 3.24 - Returns ``path`` with filename component (as returned by - ``$``) removed. After removal, any trailing - ``directory-separator`` is left alone, if present. +.. _`Boolean LINK_LANGUAGE Generator Expression`: - See :ref:`cmake_path(REMOVE_FILENAME) ` for more details. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.18 - .. versionadded:: 3.24 + ``1`` when the language used for link step matches any of the entries + in ``languages``, otherwise ``0``. This expression may be used to specify + link libraries, link options, link directories and link dependencies of a + particular language in a target. For example: - Returns ``path`` with the filename component replaced by ``input``. If - ``path`` has no filename component (i.e. ``$`` returns - ``0``), ``path`` is unchanged. + .. code-block:: cmake - See :ref:`cmake_path(REPLACE_FILENAME) ` for more details. + add_library(api_C ...) + add_library(api_CXX ...) + add_library(api INTERFACE) + target_link_options(api INTERFACE $<$:-opt_c> + $<$:-opt_cxx>) + target_link_libraries(api INTERFACE $<$:api_C> + $<$:api_CXX>) -.. genex:: $ + add_executable(myapp1 main.c) + target_link_options(myapp1 PRIVATE api) - .. versionadded:: 3.24 + add_executable(myapp2 main.cpp) + target_link_options(myapp2 PRIVATE api) - Returns ``path`` with the :ref:`extension ` removed, if any. - - See :ref:`cmake_path(REMOVE_EXTENSION) ` for more details. - -.. genex:: $ - - .. versionadded:: 3.24 - - Returns ``path`` with the :ref:`extension ` replaced by - ``input``, if any. - - See :ref:`cmake_path(REPLACE_EXTENSION) ` for more details. - -.. genex:: $ - - .. versionadded:: 3.24 - - Returns ``path`` normalized according to the steps described in - :ref:`Normalization`. - -.. genex:: $ - - .. versionadded:: 3.24 - - Returns ``path``, modified to make it relative to the ``base_directory`` - argument. - - See :ref:`cmake_path(RELATIVE_PATH) ` for more - details. - -.. genex:: $ - - .. versionadded:: 3.24 - - Returns ``path`` as absolute. If ``path`` is a relative path - (``$`` returns ``1``), it is evaluated relative to the - given base directory specified by ``base_directory`` argument. - - When the ``NORMALIZE`` option is specified, the path is - :ref:`normalized ` after the path computation. - - See :ref:`cmake_path(ABSOLUTE_PATH) ` for more details. - -Variable Queries -^^^^^^^^^^^^^^^^ - -.. genex:: $ - - Configuration name. - -.. genex:: $ - - Configuration name. Deprecated since CMake 3.0. Use ``CONFIG`` instead. - -.. genex:: $ - - The current system's CMake platform id. - See also the :variable:`CMAKE_SYSTEM_NAME` variable. - -.. genex:: $ - - CMake's compiler id of the C compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - CMake's compiler id of the CXX compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - .. versionadded:: 3.15 - - CMake's compiler id of the CUDA compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - .. versionadded:: 3.16 - - CMake's compiler id of the OBJC compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - .. versionadded:: 3.16 - - CMake's compiler id of the OBJCXX compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - CMake's compiler id of the Fortran compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - .. versionadded:: 3.21 - - CMake's compiler id of the HIP compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - .. versionadded:: 3.19 - - CMake's compiler id of the ISPC compiler used. - See also the :variable:`CMAKE__COMPILER_ID` variable. - -.. genex:: $ - - The version of the C compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ - - The version of the CXX compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ - - .. versionadded:: 3.15 - - The version of the CUDA compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ - - .. versionadded:: 3.16 - - The version of the OBJC compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ - - .. versionadded:: 3.16 - - The version of the OBJCXX compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ - - The version of the Fortran compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. - -.. genex:: $ + This specifies to use the ``api`` target for linking targets ``myapp1`` and + ``myapp2``. In practice, ``myapp1`` will link with target ``api_C`` and + option ``-opt_c`` because it will use ``C`` as link language. And ``myapp2`` + will link with ``api_CXX`` and option ``-opt_cxx`` because ``CXX`` will be + the link language. - .. versionadded:: 3.21 + .. _`Constraints LINK_LANGUAGE Generator Expression`: - The version of the HIP compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + .. note:: -.. genex:: $ + To determine the link language of a target, it is required to collect, + transitively, all the targets which will be linked to it. So, for link + libraries properties, a double evaluation will be done. During the first + evaluation, ``$`` expressions will always return ``0``. + The link language computed after this first pass will be used to do the + second pass. To avoid inconsistency, it is required that the second pass + do not change the link language. Moreover, to avoid unexpected + side-effects, it is required to specify complete entities as part of the + ``$`` expression. For example: - .. versionadded:: 3.19 + .. code-block:: cmake - The version of the ISPC compiler used. - See also the :variable:`CMAKE__COMPILER_VERSION` variable. + add_library(lib STATIC file.cxx) + add_library(libother STATIC file.c) -.. genex:: $ + # bad usage + add_executable(myapp1 main.c) + target_link_libraries(myapp1 PRIVATE lib$<$:other>) - .. versionadded:: 3.3 + # correct usage + add_executable(myapp2 main.c) + target_link_libraries(myapp2 PRIVATE $<$:libother>) - The compile language of source files when evaluating compile options. - See :ref:`the related boolean expression - ` - ``$`` - for notes about the portability of this generator expression. + In this example, for ``myapp1``, the first pass will, unexpectedly, + determine that the link language is ``CXX`` because the evaluation of the + generator expression will be an empty string so ``myapp1`` will depends on + target ``lib`` which is ``C++``. On the contrary, for ``myapp2``, the first + evaluation will give ``C`` as link language, so the second pass will + correctly add target ``libother`` as link dependency. -.. genex:: $ +.. genex:: $ .. versionadded:: 3.18 - The link language of the target when evaluating link options. - See :ref:`the related boolean expression - ` ``$`` - for notes about the portability of this generator expression. - - .. note:: - - This generator expression is not supported by the link libraries - properties to avoid side-effects due to the double evaluation of - these properties. - -.. _`Target-Dependent Queries`: + ``1`` when the language used for link step matches ``language`` and the + CMake's compiler id of the language linker matches any one of the entries + in ``compiler_ids``, otherwise ``0``. This expression is a short form for the + combination of ``$`` and + ``$``. This expression may be used to specify + link libraries, link options, link directories and link dependencies of a + particular language and linker combination in a target. For example: -Target-Dependent Queries -^^^^^^^^^^^^^^^^^^^^^^^^ + .. code-block:: cmake -These queries refer to a target ``tgt``. This can be any runtime artifact, -namely: + add_library(libC_Clang ...) + add_library(libCXX_Clang ...) + add_library(libC_Intel ...) + add_library(libCXX_Intel ...) -* an executable target created by :command:`add_executable` -* a shared library target (``.so``, ``.dll`` but not their ``.lib`` import library) - created by :command:`add_library` -* a static library target created by :command:`add_library` + add_executable(myapp main.c) + if (CXX_CONFIG) + target_sources(myapp PRIVATE file.cxx) + endif() + target_link_libraries(myapp + PRIVATE $<$:libCXX_Clang> + $<$:libC_Clang> + $<$:libCXX_Intel> + $<$:libC_Intel>) -In the following, "the ``tgt`` filename" means the name of the ``tgt`` -binary file. This has to be distinguished from "the target name", -which is just the string ``tgt``. + This specifies the use of different link libraries based on both the + compiler id and link language. This example will have target ``libCXX_Clang`` + as link dependency when ``Clang`` or ``AppleClang`` is the ``CXX`` + linker, and ``libCXX_Intel`` when ``Intel`` is the ``CXX`` linker. + Likewise when the ``C`` linker is ``Clang`` or ``AppleClang``, target + ``libC_Clang`` will be added as link dependency and ``libC_Intel`` when + ``Intel`` is the ``C`` linker. -.. genex:: $ + See :ref:`the note related to + ` + ``$`` for constraints about the usage of this + generator expression. - .. versionadded:: 3.12 +Link Features +^^^^^^^^^^^^^ - The target name ``tgt`` if the target exists, an empty string otherwise. +.. genex:: $ - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + .. versionadded:: 3.24 -.. genex:: $ + Specify a set of libraries to link to a target, along with a ``feature`` + which provides details about *how* they should be linked. For example: - Full path to the ``tgt`` binary file. + .. code-block:: cmake - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on, unless the expression is being used in - :command:`add_custom_command` or :command:`add_custom_target`. + add_library(lib1 STATIC ...) + add_library(lib2 ...) + target_link_libraries(lib2 PRIVATE "$") -.. genex:: $ + This specifies that ``lib2`` should link to ``lib1`` and use the + ``WHOLE_ARCHIVE`` feature when doing so. - .. versionadded:: 3.15 + Feature names are case-sensitive and may only contain letters, numbers and + underscores. Feature names defined in all uppercase are reserved for CMake's + own built-in features. The pre-defined built-in library features are: - Base name of ``tgt``, i.e. ``$`` without prefix and - suffix. - For example, if the ``tgt`` filename is ``libbase.so``, the base name is ``base``. + .. include:: ../variable/LINK_LIBRARY_PREDEFINED_FEATURES.txt - See also the :prop_tgt:`OUTPUT_NAME`, :prop_tgt:`ARCHIVE_OUTPUT_NAME`, - :prop_tgt:`LIBRARY_OUTPUT_NAME` and :prop_tgt:`RUNTIME_OUTPUT_NAME` - target properties and their configuration specific variants - :prop_tgt:`OUTPUT_NAME_`, :prop_tgt:`ARCHIVE_OUTPUT_NAME_`, - :prop_tgt:`LIBRARY_OUTPUT_NAME_` and - :prop_tgt:`RUNTIME_OUTPUT_NAME_`. + Built-in and custom library features are defined in terms of the following + variables: - The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target - properties can also be considered. + * :variable:`CMAKE__LINK_LIBRARY_USING__SUPPORTED` + * :variable:`CMAKE__LINK_LIBRARY_USING_` + * :variable:`CMAKE_LINK_LIBRARY_USING__SUPPORTED` + * :variable:`CMAKE_LINK_LIBRARY_USING_` - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + The value used for each of these variables is the value as set at the end of + the directory scope in which the target was created. The usage is as follows: -.. genex:: $ + 1. If the language-specific + :variable:`CMAKE__LINK_LIBRARY_USING__SUPPORTED` variable + is true, the ``feature`` must be defined by the corresponding + :variable:`CMAKE__LINK_LIBRARY_USING_` variable. + 2. If no language-specific ``feature`` is supported, then the + :variable:`CMAKE_LINK_LIBRARY_USING__SUPPORTED` variable must be + true and the ``feature`` must be defined by the corresponding + :variable:`CMAKE_LINK_LIBRARY_USING_` variable. - .. versionadded:: 3.15 + The following limitations should be noted: - Prefix of the ``tgt`` filename (such as ``lib``). + * The ``library-list`` can specify CMake targets or libraries. + Any CMake target of type :ref:`OBJECT ` + or :ref:`INTERFACE ` will ignore the feature aspect + of the expression and instead be linked in the standard way. - See also the :prop_tgt:`PREFIX` target property. + * The ``$`` generator expression can only be used to + specify link libraries. In practice, this means it can appear in the + :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INTERFACE_LINK_LIBRARIES`, and + :prop_tgt:`INTERFACE_LINK_LIBRARIES_DIRECT` target properties, and be + specified in :command:`target_link_libraries` and :command:`link_libraries` + commands. - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + * If a ``$`` generator expression appears in the + :prop_tgt:`INTERFACE_LINK_LIBRARIES` property of a target, it will be + included in the imported target generated by a :command:`install(EXPORT)` + command. It is the responsibility of the environment consuming this + import to define the link feature used by this expression. -.. genex:: $ + * Each target or library involved in the link step must have at most only + one kind of library feature. The absence of a feature is also incompatible + with all other features. For example: - .. versionadded:: 3.15 + .. code-block:: cmake - Suffix of the ``tgt`` filename (extension such as ``.so`` or ``.exe``). + add_library(lib1 ...) + add_library(lib2 ...) + add_library(lib3 ...) - See also the :prop_tgt:`SUFFIX` target property. + # lib1 will be associated with feature1 + target_link_libraries(lib2 PUBLIC "$") - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + # lib1 is being linked with no feature here. This conflicts with the + # use of feature1 in the line above and would result in an error. + target_link_libraries(lib3 PRIVATE lib1 lib2) -.. genex:: $ + Where it isn't possible to use the same feature throughout a build for a + given target or library, the :prop_tgt:`LINK_LIBRARY_OVERRIDE` and + :prop_tgt:`LINK_LIBRARY_OVERRIDE_` target properties can be + used to resolve such incompatibilities. - The ``tgt`` filename. + * The ``$`` generator expression does not guarantee + that the list of specified targets and libraries will be kept grouped + together. To manage constructs like ``--start-group`` and ``--end-group``, + as supported by the GNU ``ld`` linker, use the :genex:`LINK_GROUP` + generator expression instead. - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.24 - Directory of the ``tgt`` binary file. + Specify a group of libraries to link to a target, along with a ``feature`` + which defines how that group should be linked. For example: - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + .. code-block:: cmake -.. genex:: $ + add_library(lib1 STATIC ...) + add_library(lib2 ...) + target_link_libraries(lib2 PRIVATE "$") - File used when linking to the ``tgt`` target. This will usually - be the library that ``tgt`` represents (``.a``, ``.lib``, ``.so``), - but for a shared library on DLL platforms, it would be the ``.lib`` - import library associated with the DLL. + This specifies that ``lib2`` should link to ``lib1`` and ``external``, and + that both of those two libraries should be included on the linker command + line according to the definition of the ``RESCAN`` feature. -.. genex:: $ + Feature names are case-sensitive and may only contain letters, numbers and + underscores. Feature names defined in all uppercase are reserved for CMake's + own built-in features. Currently, there is only one pre-defined built-in + group feature: - .. versionadded:: 3.15 + .. include:: ../variable/LINK_GROUP_PREDEFINED_FEATURES.txt - Base name of file used to link the target ``tgt``, i.e. - ``$`` without prefix and suffix. For example, - if target file name is ``libbase.a``, the base name is ``base``. + Built-in and custom group features are defined in terms of the following + variables: - See also the :prop_tgt:`OUTPUT_NAME`, :prop_tgt:`ARCHIVE_OUTPUT_NAME`, - and :prop_tgt:`LIBRARY_OUTPUT_NAME` target properties and their configuration - specific variants :prop_tgt:`OUTPUT_NAME_`, - :prop_tgt:`ARCHIVE_OUTPUT_NAME_` and - :prop_tgt:`LIBRARY_OUTPUT_NAME_`. + * :variable:`CMAKE__LINK_GROUP_USING__SUPPORTED` + * :variable:`CMAKE__LINK_GROUP_USING_` + * :variable:`CMAKE_LINK_GROUP_USING__SUPPORTED` + * :variable:`CMAKE_LINK_GROUP_USING_` - The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target - properties can also be considered. + The value used for each of these variables is the value as set at the end of + the directory scope in which the target was created. The usage is as follows: - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + 1. If the language-specific + :variable:`CMAKE__LINK_GROUP_USING__SUPPORTED` variable + is true, the ``feature`` must be defined by the corresponding + :variable:`CMAKE__LINK_GROUP_USING_` variable. + 2. If no language-specific ``feature`` is supported, then the + :variable:`CMAKE_LINK_GROUP_USING__SUPPORTED` variable must be + true and the ``feature`` must be defined by the corresponding + :variable:`CMAKE_LINK_GROUP_USING_` variable. -.. genex:: $ + The ``LINK_GROUP`` generator expression is compatible with the + :genex:`LINK_LIBRARY` generator expression. The libraries involved in a + group can be specified using the :genex:`LINK_LIBRARY` generator expression. - .. versionadded:: 3.15 + Each target or external library involved in the link step is allowed to be + part of multiple groups, but only if all the groups involved specify the + same ``feature``. Such groups will not be merged on the linker command line, + the individual groups will still be preserved. Mixing different group + features for the same target or library is forbidden. - Prefix of file used to link target ``tgt``. + .. code-block:: cmake - See also the :prop_tgt:`PREFIX` and :prop_tgt:`IMPORT_PREFIX` target - properties. + add_library(lib1 ...) + add_library(lib2 ...) + add_library(lib3 ...) + add_library(lib4 ...) + add_library(lib5 ...) - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + target_link_libraries(lib3 PUBLIC "$") + target_link_libraries(lib4 PRIVATE "$") + # lib4 will be linked with the groups {lib1,lib2} and {lib1,lib3}. + # Both groups specify the same feature, so this is fine. -.. genex:: $ + target_link_libraries(lib5 PRIVATE "$") + # An error will be raised here because both lib1 and lib3 are part of two + # groups with different features. - .. versionadded:: 3.15 + When a target or an external library is involved in the link step as part of + a group and also as not part of any group, any occurrence of the non-group + link item will be replaced by the groups it belongs to. - Suffix of file used to link where ``tgt`` is the name of a target. + .. code-block:: cmake - The suffix corresponds to the file extension (such as ".so" or ".lib"). + add_library(lib1 ...) + add_library(lib2 ...) + add_library(lib3 ...) + add_library(lib4 ...) - See also the :prop_tgt:`SUFFIX` and :prop_tgt:`IMPORT_SUFFIX` target - properties. + target_link_libraries(lib3 PUBLIC lib1) - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + target_link_libraries(lib4 PRIVATE lib3 "$") + # lib4 will only be linked with lib3 and the group {lib1,lib2} -.. genex:: $ + Because ``lib1`` is part of the group defined for ``lib4``, that group then + gets applied back to the use of ``lib1`` for ``lib3``. The end result will + be as though the linking relationship for ``lib3`` had been specified as: - Name of file used to link target ``tgt``. + .. code-block:: cmake - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + target_link_libraries(lib3 PUBLIC "$") -.. genex:: $ + Be aware that the precedence of the group over the non-group link item can + result in circular dependencies between groups. If this occurs, a fatal + error is raised because circular dependencies are not allowed for groups. - Directory of file used to link target ``tgt``. + .. code-block:: cmake - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + add_library(lib1A ...) + add_library(lib1B ...) + add_library(lib2A ...) + add_library(lib2B ...) + add_library(lib3 ...) -.. genex:: $ + # Non-group linking relationships, these are non-circular so far + target_link_libraries(lib1A PUBLIC lib2A) + target_link_libraries(lib2B PUBLIC lib1B) - File with soname (``.so.3``) where ``tgt`` is the name of a target. -.. genex:: $ + # The addition of these groups creates circular dependencies + target_link_libraries(lib3 PRIVATE + "$" + "$" + ) - Name of file with soname (``.so.3``). + Because of the groups defined for ``lib3``, the linking relationships for + ``lib1A`` and ``lib2B`` effectively get expanded to the equivalent of: - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + .. code-block:: cmake -.. genex:: $ + target_link_libraries(lib1A PUBLIC "$") + target_link_libraries(lib2B PUBLIC "$") - Directory of with soname (``.so.3``). + This creates a circular dependency between groups: + ``lib1A --> lib2B --> lib1A``. - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + The following limitations should also be noted: -.. genex:: $ + * The ``library-list`` can specify CMake targets or libraries. + Any CMake target of type :ref:`OBJECT ` + or :ref:`INTERFACE ` will ignore the feature aspect + of the expression and instead be linked in the standard way. - .. versionadded:: 3.1 + * The ``$`` generator expression can only be used to + specify link libraries. In practice, this means it can appear in the + :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INTERFACE_LINK_LIBRARIES`,and + :prop_tgt:`INTERFACE_LINK_LIBRARIES_DIRECT` target properties, and be + specified in :command:`target_link_libraries` and :command:`link_libraries` + commands. - Full path to the linker generated program database file (.pdb) - where ``tgt`` is the name of a target. + * If a ``$`` generator expression appears in the + :prop_tgt:`INTERFACE_LINK_LIBRARIES` property of a target, it will be + included in the imported target generated by a :command:`install(EXPORT)` + command. It is the responsibility of the environment consuming this + import to define the link feature used by this expression. - See also the :prop_tgt:`PDB_NAME` and :prop_tgt:`PDB_OUTPUT_DIRECTORY` - target properties and their configuration specific variants - :prop_tgt:`PDB_NAME_` and :prop_tgt:`PDB_OUTPUT_DIRECTORY_`. +Link Context +^^^^^^^^^^^^ -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.15 + .. versionadded:: 3.1 - Base name of the linker generated program database file (.pdb) - where ``tgt`` is the name of a target. + Content of ``...``, except while collecting :ref:`Target Usage Requirements`, + in which case it is the empty string. This is intended for use in an + :prop_tgt:`INTERFACE_LINK_LIBRARIES` target property, typically populated + via the :command:`target_link_libraries` command, to specify private link + dependencies without other usage requirements. - The base name corresponds to the target PDB file name (see - ``$``) without prefix and suffix. For example, - if target file name is ``base.pdb``, the base name is ``base``. + .. versionadded:: 3.24 + ``LINK_ONLY`` may also be used in a :prop_tgt:`LINK_LIBRARIES` target + property. See policy :policy:`CMP0131`. - See also the :prop_tgt:`PDB_NAME` target property and its configuration - specific variant :prop_tgt:`PDB_NAME_`. +.. genex:: $ - The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target - properties can also be considered. + .. versionadded:: 3.18 - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on. + Returns the list if it is the device link step, an empty list otherwise. + The device link step is controlled by :prop_tgt:`CUDA_SEPARABLE_COMPILATION` + and :prop_tgt:`CUDA_RESOLVE_DEVICE_SYMBOLS` properties and + policy :policy:`CMP0105`. This expression can only be used to specify link + options. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.1 + .. versionadded:: 3.18 - Name of the linker generated program database file (.pdb). + Returns the list if it is the normal link step, an empty list otherwise. + This expression is mainly useful when a device link step is also involved + (see :genex:`$` generator expression). This expression can + only be used to specify link options. - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). -.. genex:: $ +.. _`Target-Dependent Queries`: - .. versionadded:: 3.1 +Target-Dependent Expressions +---------------------------- - Directory of the linker generated program database file (.pdb). +These queries refer to a target ``tgt``. Unless otherwise stated, this can +be any runtime artifact, namely: - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). +* An executable target created by :command:`add_executable`. +* A shared library target (``.so``, ``.dll`` but not their ``.lib`` import + library) created by :command:`add_library`. +* A static library target created by :command:`add_library`. -.. genex:: $ +In the following, the phrase "the ``tgt`` filename" means the name of the +``tgt`` binary file. This has to be distinguished from the phrase +"the target name", which is just the string ``tgt``. - .. versionadded:: 3.9 +.. genex:: $ - Full path to the bundle directory (``/path/to/my.app``, - ``/path/to/my.framework``, or ``/path/to/my.bundle``), - where ``tgt`` is the name of a target. + .. versionadded:: 3.12 - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + ``1`` if ``tgt`` exists as a CMake target, else ``0``. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.24 + .. versionadded:: 3.12 - Name of the bundle directory (``my.app``, ``my.framework``, or - ``my.bundle``), where ``tgt`` is the name of a target. + The target name ``tgt`` if the target exists, an empty string otherwise. Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). - -.. genex:: $ - - .. versionadded:: 3.9 + expression is evaluated on. - Full path to the bundle content directory where ``tgt`` is the name of a - target. For the macOS SDK it leads to ``/path/to/my.app/Contents``, - ``/path/to/my.framework``, or ``/path/to/my.bundle/Contents``. - For all other SDKs (e.g. iOS) it leads to ``/path/to/my.app``, - ``/path/to/my.framework``, or ``/path/to/my.bundle`` due to the flat - bundle structure. +.. genex:: $ - Note that ``tgt`` is not added as a dependency of the target this - expression is evaluated on (see policy :policy:`CMP0112`). + Marks ``...`` as being the name of a target. This is required if exporting + targets to multiple dependent export sets. The ``...`` must be a literal + name of a target, it may not contain generator expressions. .. genex:: $ @@ -1320,326 +1313,290 @@ which is just the string ``tgt``. :ref:`Target Usage Requirements` this is the consuming target rather than the target specifying the requirement. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.21 + .. versionadded:: 3.1 - List of DLLs that the target depends on at runtime. This is determined by - the locations of all the ``SHARED`` targets in the target's transitive - dependencies. Using this generator expression on targets other than - executables, ``SHARED`` libraries, and ``MODULE`` libraries is an error. - **On non-DLL platforms, this expression always evaluates to an empty string**. + List of objects resulting from building ``tgt``. This would typically be + used on :ref:`object library ` targets. - This generator expression can be used to copy all of the DLLs that a target - depends on into its output directory in a ``POST_BUILD`` custom command. For - example: +.. genex:: $ - .. code-block:: cmake + ``1`` if the ``policy`` was ``NEW`` when the 'head' target was created, + else ``0``. If the ``policy`` was not set, the warning message for the policy + will be emitted. This generator expression only works for a subset of + policies. - find_package(foo CONFIG REQUIRED) # package generated by install(EXPORT) +.. genex:: $ - add_executable(exe main.c) - target_link_libraries(exe PRIVATE foo::foo foo::bar) - add_custom_command(TARGET exe POST_BUILD - COMMAND ${CMAKE_COMMAND} -E copy $ $ - COMMAND_EXPAND_LISTS - ) + Full path to the ``tgt`` binary file. - .. note:: + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on, unless the expression is being used in + :command:`add_custom_command` or :command:`add_custom_target`. - :ref:`Imported Targets` are supported only if they know the location - of their ``.dll`` files. An imported ``SHARED`` library must have - :prop_tgt:`IMPORTED_LOCATION` set to its ``.dll`` file. See the - :ref:`add_library imported libraries ` - section for details. Many :ref:`Find Modules` produce imported targets - with the ``UNKNOWN`` type and therefore will be ignored. +.. genex:: $ -.. genex:: $ + .. versionadded:: 3.15 - Content of the install prefix when the target is exported via - :command:`install(EXPORT)`, or when evaluated in the - :prop_tgt:`INSTALL_NAME_DIR` property or the ``INSTALL_NAME_DIR`` argument of - :command:`install(RUNTIME_DEPENDENCY_SET)`, and empty otherwise. + Base name of ``tgt``, i.e. ``$`` without prefix and + suffix. + For example, if the ``tgt`` filename is ``libbase.so``, the base name is ``base``. -Output-Related Expressions -^^^^^^^^^^^^^^^^^^^^^^^^^^ + See also the :prop_tgt:`OUTPUT_NAME`, :prop_tgt:`ARCHIVE_OUTPUT_NAME`, + :prop_tgt:`LIBRARY_OUTPUT_NAME` and :prop_tgt:`RUNTIME_OUTPUT_NAME` + target properties and their configuration specific variants + :prop_tgt:`OUTPUT_NAME_`, :prop_tgt:`ARCHIVE_OUTPUT_NAME_`, + :prop_tgt:`LIBRARY_OUTPUT_NAME_` and + :prop_tgt:`RUNTIME_OUTPUT_NAME_`. -.. genex:: $ + The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target + properties can also be considered. - Marks ``...`` as being the name of a target. This is required if exporting - targets to multiple dependent export sets. The ``...`` must be a literal - name of a target, it may not contain generator expressions. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.1 + .. versionadded:: 3.15 - Content of ``...``, except while collecting :ref:`Target Usage Requirements`, - in which case it is the empty string. This is intended for use in an - :prop_tgt:`INTERFACE_LINK_LIBRARIES` target property, typically populated - via the :command:`target_link_libraries` command, to specify private link - dependencies without other usage requirements. + Prefix of the ``tgt`` filename (such as ``lib``). - .. versionadded:: 3.24 - ``LINK_ONLY`` may also be used in a :prop_tgt:`LINK_LIBRARIES` target - property. See policy :policy:`CMP0131`. + See also the :prop_tgt:`PREFIX` target property. -.. genex:: $ + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. - .. versionadded:: 3.18 +.. genex:: $ - Returns the list if it is the device link step, an empty list otherwise. - The device link step is controlled by :prop_tgt:`CUDA_SEPARABLE_COMPILATION` - and :prop_tgt:`CUDA_RESOLVE_DEVICE_SYMBOLS` properties and - policy :policy:`CMP0105`. This expression can only be used to specify link - options. + .. versionadded:: 3.15 -.. genex:: $ + Suffix of the ``tgt`` filename (extension such as ``.so`` or ``.exe``). - .. versionadded:: 3.18 + See also the :prop_tgt:`SUFFIX` target property. - Returns the list if it is the normal link step, an empty list otherwise. - This expression is mainly useful when a device link step is also involved - (see :genex:`$` generator expression). This expression can - only be used to specify link options. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. -.. genex:: $ +.. genex:: $ - .. versionadded:: 3.24 + The ``tgt`` filename. - Specify a set of libraries to link to a target, along with a ``feature`` - which provides details about *how* they should be linked. For example: + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - .. code-block:: cmake +.. genex:: $ - add_library(lib1 STATIC ...) - add_library(lib2 ...) - target_link_libraries(lib2 PRIVATE "$") + Directory of the ``tgt`` binary file. - This specifies that ``lib2`` should link to ``lib1`` and use the - ``WHOLE_ARCHIVE`` feature when doing so. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - Feature names are case-sensitive and may only contain letters, numbers and - underscores. Feature names defined in all uppercase are reserved for CMake's - own built-in features. The pre-defined built-in library features are: +.. genex:: $ - .. include:: ../variable/LINK_LIBRARY_PREDEFINED_FEATURES.txt + File used when linking to the ``tgt`` target. This will usually + be the library that ``tgt`` represents (``.a``, ``.lib``, ``.so``), + but for a shared library on DLL platforms, it would be the ``.lib`` + import library associated with the DLL. - Built-in and custom library features are defined in terms of the following - variables: +.. genex:: $ - * :variable:`CMAKE__LINK_LIBRARY_USING__SUPPORTED` - * :variable:`CMAKE__LINK_LIBRARY_USING_` - * :variable:`CMAKE_LINK_LIBRARY_USING__SUPPORTED` - * :variable:`CMAKE_LINK_LIBRARY_USING_` + .. versionadded:: 3.15 - The value used for each of these variables is the value as set at the end of - the directory scope in which the target was created. The usage is as follows: + Base name of file used to link the target ``tgt``, i.e. + ``$`` without prefix and suffix. For example, + if target file name is ``libbase.a``, the base name is ``base``. - 1. If the language-specific - :variable:`CMAKE__LINK_LIBRARY_USING__SUPPORTED` variable - is true, the ``feature`` must be defined by the corresponding - :variable:`CMAKE__LINK_LIBRARY_USING_` variable. - 2. If no language-specific ``feature`` is supported, then the - :variable:`CMAKE_LINK_LIBRARY_USING__SUPPORTED` variable must be - true and the ``feature`` must be defined by the corresponding - :variable:`CMAKE_LINK_LIBRARY_USING_` variable. + See also the :prop_tgt:`OUTPUT_NAME`, :prop_tgt:`ARCHIVE_OUTPUT_NAME`, + and :prop_tgt:`LIBRARY_OUTPUT_NAME` target properties and their configuration + specific variants :prop_tgt:`OUTPUT_NAME_`, + :prop_tgt:`ARCHIVE_OUTPUT_NAME_` and + :prop_tgt:`LIBRARY_OUTPUT_NAME_`. - The following limitations should be noted: + The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target + properties can also be considered. - * The ``library-list`` can specify CMake targets or libraries. - Any CMake target of type :ref:`OBJECT ` - or :ref:`INTERFACE ` will ignore the feature aspect - of the expression and instead be linked in the standard way. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. - * The ``$`` generator expression can only be used to - specify link libraries. In practice, this means it can appear in the - :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INTERFACE_LINK_LIBRARIES`, and - :prop_tgt:`INTERFACE_LINK_LIBRARIES_DIRECT` target properties, and be - specified in :command:`target_link_libraries` and :command:`link_libraries` - commands. +.. genex:: $ - * If a ``$`` generator expression appears in the - :prop_tgt:`INTERFACE_LINK_LIBRARIES` property of a target, it will be - included in the imported target generated by a :command:`install(EXPORT)` - command. It is the responsibility of the environment consuming this - import to define the link feature used by this expression. + .. versionadded:: 3.15 - * Each target or library involved in the link step must have at most only - one kind of library feature. The absence of a feature is also incompatible - with all other features. For example: + Prefix of file used to link target ``tgt``. - .. code-block:: cmake + See also the :prop_tgt:`PREFIX` and :prop_tgt:`IMPORT_PREFIX` target + properties. - add_library(lib1 ...) - add_library(lib2 ...) - add_library(lib3 ...) + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. - # lib1 will be associated with feature1 - target_link_libraries(lib2 PUBLIC "$") +.. genex:: $ - # lib1 is being linked with no feature here. This conflicts with the - # use of feature1 in the line above and would result in an error. - target_link_libraries(lib3 PRIVATE lib1 lib2) + .. versionadded:: 3.15 - Where it isn't possible to use the same feature throughout a build for a - given target or library, the :prop_tgt:`LINK_LIBRARY_OVERRIDE` and - :prop_tgt:`LINK_LIBRARY_OVERRIDE_` target properties can be - used to resolve such incompatibilities. + Suffix of file used to link where ``tgt`` is the name of a target. - * The ``$`` generator expression does not guarantee - that the list of specified targets and libraries will be kept grouped - together. To manage constructs like ``--start-group`` and ``--end-group``, - as supported by the GNU ``ld`` linker, use the :genex:`LINK_GROUP` - generator expression instead. + The suffix corresponds to the file extension (such as ".so" or ".lib"). -.. genex:: $ + See also the :prop_tgt:`SUFFIX` and :prop_tgt:`IMPORT_SUFFIX` target + properties. - .. versionadded:: 3.24 + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. - Specify a group of libraries to link to a target, along with a ``feature`` - which defines how that group should be linked. For example: +.. genex:: $ - .. code-block:: cmake + Name of file used to link target ``tgt``. - add_library(lib1 STATIC ...) - add_library(lib2 ...) - target_link_libraries(lib2 PRIVATE "$") + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). + +.. genex:: $ + + Directory of file used to link target ``tgt``. + + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). + +.. genex:: $ + + File with soname (``.so.3``) where ``tgt`` is the name of a target. +.. genex:: $ + + Name of file with soname (``.so.3``). + + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). + +.. genex:: $ + + Directory of with soname (``.so.3``). + + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). + +.. genex:: $ + + .. versionadded:: 3.1 + + Full path to the linker generated program database file (.pdb) + where ``tgt`` is the name of a target. + + See also the :prop_tgt:`PDB_NAME` and :prop_tgt:`PDB_OUTPUT_DIRECTORY` + target properties and their configuration specific variants + :prop_tgt:`PDB_NAME_` and :prop_tgt:`PDB_OUTPUT_DIRECTORY_`. + +.. genex:: $ + + .. versionadded:: 3.15 + + Base name of the linker generated program database file (.pdb) + where ``tgt`` is the name of a target. - This specifies that ``lib2`` should link to ``lib1`` and ``external``, and - that both of those two libraries should be included on the linker command - line according to the definition of the ``RESCAN`` feature. + The base name corresponds to the target PDB file name (see + ``$``) without prefix and suffix. For example, + if target file name is ``base.pdb``, the base name is ``base``. - Feature names are case-sensitive and may only contain letters, numbers and - underscores. Feature names defined in all uppercase are reserved for CMake's - own built-in features. Currently, there is only one pre-defined built-in - group feature: + See also the :prop_tgt:`PDB_NAME` target property and its configuration + specific variant :prop_tgt:`PDB_NAME_`. - .. include:: ../variable/LINK_GROUP_PREDEFINED_FEATURES.txt + The :prop_tgt:`_POSTFIX` and :prop_tgt:`DEBUG_POSTFIX` target + properties can also be considered. - Built-in and custom group features are defined in terms of the following - variables: + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on. - * :variable:`CMAKE__LINK_GROUP_USING__SUPPORTED` - * :variable:`CMAKE__LINK_GROUP_USING_` - * :variable:`CMAKE_LINK_GROUP_USING__SUPPORTED` - * :variable:`CMAKE_LINK_GROUP_USING_` +.. genex:: $ - The value used for each of these variables is the value as set at the end of - the directory scope in which the target was created. The usage is as follows: + .. versionadded:: 3.1 - 1. If the language-specific - :variable:`CMAKE__LINK_GROUP_USING__SUPPORTED` variable - is true, the ``feature`` must be defined by the corresponding - :variable:`CMAKE__LINK_GROUP_USING_` variable. - 2. If no language-specific ``feature`` is supported, then the - :variable:`CMAKE_LINK_GROUP_USING__SUPPORTED` variable must be - true and the ``feature`` must be defined by the corresponding - :variable:`CMAKE_LINK_GROUP_USING_` variable. + Name of the linker generated program database file (.pdb). - The ``LINK_GROUP`` generator expression is compatible with the - :genex:`LINK_LIBRARY` generator expression. The libraries involved in a - group can be specified using the :genex:`LINK_LIBRARY` generator expression. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - Each target or external library involved in the link step is allowed to be - part of multiple groups, but only if all the groups involved specify the - same ``feature``. Such groups will not be merged on the linker command line, - the individual groups will still be preserved. Mixing different group - features for the same target or library is forbidden. +.. genex:: $ - .. code-block:: cmake + .. versionadded:: 3.1 - add_library(lib1 ...) - add_library(lib2 ...) - add_library(lib3 ...) - add_library(lib4 ...) - add_library(lib5 ...) + Directory of the linker generated program database file (.pdb). - target_link_libraries(lib3 PUBLIC "$") - target_link_libraries(lib4 PRIVATE "$") - # lib4 will be linked with the groups {lib1,lib2} and {lib1,lib3}. - # Both groups specify the same feature, so this is fine. + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - target_link_libraries(lib5 PRIVATE "$") - # An error will be raised here because both lib1 and lib3 are part of two - # groups with different features. +.. genex:: $ - When a target or an external library is involved in the link step as part of - a group and also as not part of any group, any occurrence of the non-group - link item will be replaced by the groups it belongs to. + .. versionadded:: 3.9 - .. code-block:: cmake + Full path to the bundle directory (``/path/to/my.app``, + ``/path/to/my.framework``, or ``/path/to/my.bundle``), + where ``tgt`` is the name of a target. - add_library(lib1 ...) - add_library(lib2 ...) - add_library(lib3 ...) - add_library(lib4 ...) + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - target_link_libraries(lib3 PUBLIC lib1) +.. genex:: $ - target_link_libraries(lib4 PRIVATE lib3 "$") - # lib4 will only be linked with lib3 and the group {lib1,lib2} + .. versionadded:: 3.24 - Because ``lib1`` is part of the group defined for ``lib4``, that group then - gets applied back to the use of ``lib1`` for ``lib3``. The end result will - be as though the linking relationship for ``lib3`` had been specified as: + Name of the bundle directory (``my.app``, ``my.framework``, or + ``my.bundle``), where ``tgt`` is the name of a target. - .. code-block:: cmake + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - target_link_libraries(lib3 PUBLIC "$") +.. genex:: $ - Be aware that the precedence of the group over the non-group link item can - result in circular dependencies between groups. If this occurs, a fatal - error is raised because circular dependencies are not allowed for groups. + .. versionadded:: 3.9 - .. code-block:: cmake + Full path to the bundle content directory where ``tgt`` is the name of a + target. For the macOS SDK it leads to ``/path/to/my.app/Contents``, + ``/path/to/my.framework``, or ``/path/to/my.bundle/Contents``. + For all other SDKs (e.g. iOS) it leads to ``/path/to/my.app``, + ``/path/to/my.framework``, or ``/path/to/my.bundle`` due to the flat + bundle structure. - add_library(lib1A ...) - add_library(lib1B ...) - add_library(lib2A ...) - add_library(lib2B ...) - add_library(lib3 ...) + Note that ``tgt`` is not added as a dependency of the target this + expression is evaluated on (see policy :policy:`CMP0112`). - # Non-group linking relationships, these are non-circular so far - target_link_libraries(lib1A PUBLIC lib2A) - target_link_libraries(lib2B PUBLIC lib1B) +.. genex:: $ - # The addition of these groups creates circular dependencies - target_link_libraries(lib3 PRIVATE - "$" - "$" - ) + .. versionadded:: 3.21 - Because of the groups defined for ``lib3``, the linking relationships for - ``lib1A`` and ``lib2B`` effectively get expanded to the equivalent of: + List of DLLs that the target depends on at runtime. This is determined by + the locations of all the ``SHARED`` targets in the target's transitive + dependencies. Using this generator expression on targets other than + executables, ``SHARED`` libraries, and ``MODULE`` libraries is an error. + **On non-DLL platforms, this expression always evaluates to an empty string**. + + This generator expression can be used to copy all of the DLLs that a target + depends on into its output directory in a ``POST_BUILD`` custom command. For + example: .. code-block:: cmake - target_link_libraries(lib1A PUBLIC "$") - target_link_libraries(lib2B PUBLIC "$") + find_package(foo CONFIG REQUIRED) # package generated by install(EXPORT) - This creates a circular dependency between groups: - ``lib1A --> lib2B --> lib1A``. + add_executable(exe main.c) + target_link_libraries(exe PRIVATE foo::foo foo::bar) + add_custom_command(TARGET exe POST_BUILD + COMMAND ${CMAKE_COMMAND} -E copy $ $ + COMMAND_EXPAND_LISTS + ) - The following limitations should also be noted: + .. note:: - * The ``library-list`` can specify CMake targets or libraries. - Any CMake target of type :ref:`OBJECT ` - or :ref:`INTERFACE ` will ignore the feature aspect - of the expression and instead be linked in the standard way. + :ref:`Imported Targets` are supported only if they know the location + of their ``.dll`` files. An imported ``SHARED`` library must have + :prop_tgt:`IMPORTED_LOCATION` set to its ``.dll`` file. See the + :ref:`add_library imported libraries ` + section for details. Many :ref:`Find Modules` produce imported targets + with the ``UNKNOWN`` type and therefore will be ignored. - * The ``$`` generator expression can only be used to - specify link libraries. In practice, this means it can appear in the - :prop_tgt:`LINK_LIBRARIES`, :prop_tgt:`INTERFACE_LINK_LIBRARIES`,and - :prop_tgt:`INTERFACE_LINK_LIBRARIES_DIRECT` target properties, and be - specified in :command:`target_link_libraries` and :command:`link_libraries` - commands. - * If a ``$`` generator expression appears in the - :prop_tgt:`INTERFACE_LINK_LIBRARIES` property of a target, it will be - included in the imported target generated by a :command:`install(EXPORT)` - command. It is the responsibility of the environment consuming this - import to define the link feature used by this expression. +Export And Install Expressions +------------------------------ .. genex:: $ @@ -1652,48 +1609,85 @@ Output-Related Expressions when the target is used by another target in the same buildsystem. Expands to the empty string otherwise. -.. genex:: $ +.. genex:: $ - Content of ``...`` converted to a C identifier. The conversion follows the - same behavior as :command:`string(MAKE_C_IDENTIFIER)`. + Content of the install prefix when the target is exported via + :command:`install(EXPORT)`, or when evaluated in the + :prop_tgt:`INSTALL_NAME_DIR` property or the ``INSTALL_NAME_DIR`` argument of + :command:`install(RUNTIME_DEPENDENCY_SET)`, and empty otherwise. -.. genex:: $ +Multi-level Expression Evaluation +--------------------------------- - .. versionadded:: 3.1 +.. genex:: $ - List of objects resulting from build of ``objLib``. + .. versionadded:: 3.12 -.. genex:: $ + Content of ``expr`` evaluated as a generator expression in the current + context. This enables consumption of generator expressions whose + evaluation results itself in generator expressions. - .. versionadded:: 3.4 +.. genex:: $ - Content of ``...`` converted to shell path style. For example, slashes are - converted to backslashes in Windows shells and drive letters are converted - to posix paths in MSYS shells. The ``...`` must be an absolute path. + .. versionadded:: 3.12 - .. versionadded:: 3.14 - The ``...`` may be a :ref:`semicolon-separated list ` - of paths, in which case each path is converted individually and a result - list is generated using the shell path separator (``:`` on POSIX and - ``;`` on Windows). Be sure to enclose the argument containing this genex - in double quotes in CMake source code so that ``;`` does not split arguments. + Content of ``expr`` evaluated as a generator expression in the context of + ``tgt`` target. This enables consumption of custom target properties that + themselves contain generator expressions. -.. genex:: $ + Having the capability to evaluate generator expressions is very useful when + you want to manage custom properties supporting generator expressions. + For example: - .. versionadded:: 3.20 + .. code-block:: cmake - Only valid in :command:`add_custom_command` and :command:`add_custom_target` - as the outer-most generator expression in an argument. - With the :generator:`Ninja Multi-Config` generator, generator expressions - in ``...`` are evaluated using the custom command's "output config". - With other generators, the content of ``...`` is evaluated normally. + add_library(foo ...) -.. genex:: $ + set_property(TARGET foo PROPERTY + CUSTOM_KEYS $<$:FOO_EXTRA_THINGS> + ) - .. versionadded:: 3.20 + add_custom_target(printFooKeys + COMMAND ${CMAKE_COMMAND} -E echo $ + ) - Only valid in :command:`add_custom_command` and :command:`add_custom_target` - as the outer-most generator expression in an argument. - With the :generator:`Ninja Multi-Config` generator, generator expressions - in ``...`` are evaluated using the custom command's "command config". - With other generators, the content of ``...`` is evaluated normally. + This naive implementation of the ``printFooKeys`` custom command is wrong + because ``CUSTOM_KEYS`` target property is not evaluated and the content + is passed as is (i.e. ``$<$:FOO_EXTRA_THINGS>``). + + To have the expected result (i.e. ``FOO_EXTRA_THINGS`` if config is + ``Debug``), it is required to evaluate the output of + ``$``: + + .. code-block:: cmake + + add_custom_target(printFooKeys + COMMAND ${CMAKE_COMMAND} -E + echo $> + ) + +Escaped Characters +------------------ + +These expressions evaluate to specific string literals. Use them in place of +the actual string literal where you need to prevent them from having their +special meaning. + +.. genex:: $ + + A literal ``>``. Used for example to compare strings that contain a ``>``. + +.. genex:: $ + + A literal ``,``. Used for example to compare strings which contain a ``,``. + +.. genex:: $ + + A literal ``;``. Used to prevent list expansion on an argument with ``;``. + +Deprecated Expressions +---------------------- + +.. genex:: $ + + Configuration name. Deprecated since CMake 3.0. Use :genex:`CONFIG` instead. -- cgit v0.12 From d6af93546710bb8b034f0687b68b1891b84846bd Mon Sep 17 00:00:00 2001 From: Craig Scott Date: Tue, 19 Jul 2022 17:04:38 +1000 Subject: Help: Add Whitespace And Quoting section to genex manual --- Help/manual/cmake-generator-expressions.7.rst | 87 +++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index 357a20c..9949772 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -43,6 +43,93 @@ The above would expand to ``OLD_COMPILER`` if the :variable:`CMAKE_CXX_COMPILER_VERSION _COMPILER_VERSION>` is less than 4.2.0. +Whitespace And Quoting +====================== + +Generator expressions are typically parsed after command arguments. +If a generator expression contains spaces, new lines, semicolons or +other characters that may be interpreted as command argument separators, +the whole expression should be surrounded by quotes when passed to a +command. Failure to do so may result in the expression being split and +it may no longer be recognized as a generator expression. + +When using :command:`add_custom_command` or :command:`add_custom_target`, +use the ``VERBATIM`` and ``COMMAND_EXPAND_LISTS`` options to obtain robust +argument splitting and quoting. + +.. code-block:: cmake + + # WRONG: Embedded space will be treated as an argument separator. + # This ends up not being seen as a generator expression at all. + add_custom_target(run_some_tool + COMMAND some_tool -I$, -I> + VERBATIM + ) + +.. code-block:: cmake + + # Better, but still not robust. Quotes prevent the space from splitting the + # expression. However, the tool will receive the expanded value as a single + # argument. + add_custom_target(run_some_tool + COMMAND some_tool "-I$, -I>" + VERBATIM + ) + +.. code-block:: cmake + + # Nearly correct. Using a semicolon to separate arguments and adding the + # COMMAND_EXPAND_LISTS option means that paths with spaces will be handled + # correctly. Quoting the whole expression ensures it is seen as a generator + # expression. But if the target property is empty, we will get a bare -I + # with nothing after it. + add_custom_target(run_some_tool + COMMAND some_tool "-I$,;-I>" + COMMAND_EXPAND_LISTS + VERBATIM + ) + +Using variables to build up a more complex generator expression is also a +good way to reduce errors and improve readability. The above example can be +improved further like so: + +.. code-block:: cmake + + # The $ check prevents adding anything if the property is empty, + # assuming the property value cannot be one of CMake's false constants. + set(prop "$") + add_custom_target(run_some_tool + COMMAND some_tool "$<$:-I$>" + COMMAND_EXPAND_LISTS + VERBATIM + ) + +A common mistake is to try to split a generator expression across multiple +lines with indenting: + +.. code-block:: cmake + + # WRONG: New lines and spaces all treated as argument separators, so the + # generator expression is split and not recognized correctly. + target_compile_definitions(tgt PRIVATE + $<$, + $,5> + >:HAVE_5_OR_LATER> + ) + +Again, use helper variables with well-chosen names to build up a readable +expression instead: + +.. code-block:: cmake + + set(is_gnu "$") + set(v5_or_later "$,5>") + set(meet_requirements "$") + target_compile_definitions(tgt PRIVATE + "$<${meet_requirements}:HAVE_5_OR_LATER>" + ) + Debugging ========= -- cgit v0.12