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Diffstat (limited to 'Help/manual/cmake-generator-expressions.7.rst')
| -rw-r--r-- | Help/manual/cmake-generator-expressions.7.rst | 27 |
1 files changed, 16 insertions, 11 deletions
diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst index dc5621a..85130a0 100644 --- a/Help/manual/cmake-generator-expressions.7.rst +++ b/Help/manual/cmake-generator-expressions.7.rst @@ -97,10 +97,9 @@ Available logical expressions are: compile features and a list of supported compilers. ``$<COMPILE_LANGUAGE:lang>`` ``1`` when the language used for compilation unit matches ``lang``, - otherwise ``0``. This expression may be used to specify compile options for - source files of a particular language in a target. For example, to specify - the use of the ``-fno-exceptions`` compile option (compiler id checks - elided): + otherwise ``0``. This expression may be used to specify compile options + and compile definitions for source files of a + particular language in a target. For example: .. code-block:: cmake @@ -108,10 +107,20 @@ Available logical expressions are: target_compile_options(myapp PRIVATE $<$<COMPILE_LANGUAGE:CXX>:-fno-exceptions> ) + target_compile_definitions(myapp + PRIVATE $<$<COMPILE_LANGUAGE:CXX>:COMPILING_CXX> + ) + + This specifies the use of the ``-fno-exceptions`` compile option + and ``COMPILING_CXX`` compile definition for C++ only + (compiler id checks elided). - Note that with :ref:`Visual Studio Generators` there is no way to represent + Note that with :ref:`Visual Studio Generators` and :generator:`Xcode` there + is no way to represent target-wide compile definitions 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, target-wide flags for both C and C++ sources will be evaluated + 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: @@ -125,15 +134,11 @@ Available logical expressions are: target_link_libraries(myapp myapp_c myapp_cxx) The ``Makefile`` and ``Ninja`` based generators can also use this - expression to specify compile-language specific compile definitions - and include directories: + expression to specify compile-language specific include directories: .. code-block:: cmake add_executable(myapp main.cpp foo.c bar.cpp) - target_compile_definitions(myapp - PRIVATE $<$<COMPILE_LANGUAGE:CXX>:COMPILING_CXX> - ) target_include_directories(myapp PRIVATE $<$<COMPILE_LANGUAGE:CXX>:/opt/foo/cxx_headers> ) |