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Updated: Wednesday, August 8, 2018
 
 

cmake-generator-expressions (7)

Name

cmake-generator-expressions - CMake Generator Expressions

Synopsis

Please see following description for synopsis

Description

CMake                                           CMAKE-GENERATOR-EXPRESSIONS(7)



NAME
       cmake-generator-expressions - CMake Generator Expressions

INTRODUCTION
       Generator  expressions  are evaluated during build system generation to
       produce information specific to each build configuration.

       Generator expressions are allowed in the context of many target proper-
       ties,  such as LINK_LIBRARIES, INCLUDE_DIRECTORIES, COMPILE_DEFINITIONS
       and others.  They may also be used  when  using  commands  to  populate
       those     properties,    such    as    target_link_libraries(),    tar-
       get_include_directories(), target_compile_definitions() and others.

       This means that they enable conditional  linking,  conditional  defini-
       tions  used  when  compiling,  and  conditional include directories and
       more.  The conditions may be based on the build  configuration,  target
       properties, platform information or any other queryable information.

LOGICAL EXPRESSIONS
       Logical  expressions  are used to create conditional output.  The basic
       expressions are the 0 and 1 expressions.  Because other logical expres-
       sions  evaluate to either 0 or 1, they can be composed to create condi-
       tional output:

          $<$<CONFIG:Debug>:DEBUG_MODE>

       expands to DEBUG_MODE when the Debug configuration is used, and  other-
       wise expands to nothing.

       Available logical expressions are:

       $<BOOL:...>
              1 if the ... is true, else 0

       $<AND:?[,?]...>
              1 if all ? are 1, else 0

              The ? must always be either 0 or 1 in boolean expressions.

       $<OR:?[,?]...>
              0 if all ? are 0, else 1

       $<NOT:?>
              0 if ? is 1, else 1

       $<STREQUAL:a,b>
              1 if a is STREQUAL b, else 0

       $<EQUAL:a,b>
              1 if a is EQUAL b in a numeric comparison, else 0

       $<CONFIG:cfg>
              1  if config is cfg, else 0. This is a case-insensitive compari-
              son.  The mapping in MAP_IMPORTED_CONFIG_<CONFIG> is  also  con-
              sidered by this expression when it is evaluated on a property on
              an IMPORTED target.

       $<PLATFORM_ID:comp>
              1 if the CMake-id of the platform matches comp, otherwise 0.

       $<C_COMPILER_ID:comp>
              1 if the CMake-id of the C compiler matches comp, otherwise 0.

       $<CXX_COMPILER_ID:comp>
              1 if the CMake-id of the CXX compiler matches comp, otherwise 0.

       $<VERSION_GREATER:v1,v2>
              1 if v1 is a version greater than v2, else 0.

       $<VERSION_LESS:v1,v2>
              1 if v1 is a version less than v2, else 0.

       $<VERSION_EQUAL:v1,v2>
              1 if v1 is the same version as v2, else 0.

       $<C_COMPILER_VERSION:ver>
              1 if the version of the C compiler matches ver, otherwise 0.

       $<CXX_COMPILER_VERSION:ver>
              1 if the version of the CXX compiler matches ver, otherwise 0.

       $<TARGET_POLICY:pol>
              1 if the policy pol 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.

       $<COMPILE_FEATURES:feature[,feature]...>
              1  if  all  of the feature features are available for the 'head'
              target, and 0 otherwise. If this expression is used while evalu-
              ating  the link implementation of a target and if any dependency
              transitively increases the required C_STANDARD  or  CXX_STANDARD
              for the 'head' target, an error is reported.  See the cmake-com-
              pile-features(7) manual for information on compile features  and
              a list of supported compilers.

       $<COMPILE_LANGUAGE:lang>
              1 when the language used for compilation unit matches lang, oth-
              erwise 0.  This expression 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  (com-
              piler id checks elided):

                 add_executable(myapp main.cpp foo.c bar.cpp)
                 target_compile_options(myapp
                   PRIVATE $<$<COMPILE_LANGUAGE:CXX>:-fno-exceptions>
                 )

              This generator expression has limited use because it is not pos-
              sible to use it with the  Visual  Studio  generators.   Portable
              buildsystems  would  not  use  this expression, and would create
              separate libraries for each source file language instead:

                 add_library(myapp_c foo.c)
                 add_library(myapp_cxx foo.c)
                 target_compile_options(myapp_cxx PUBLIC -fno-exceptions)
                 add_executable(myapp main.cpp)
                 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 defini-
              tions and include directories:

                 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>
                 )

INFORMATIONAL EXPRESSIONS
       These expressions expand to some information. The  information  may  be
       used directly, eg:

          include_directories(/usr/include/$<CXX_COMPILER_ID>/)

       expands  to  /usr/include/GNU/ or /usr/include/Clang/ etc, depending on
       the Id of the compiler.

       These expressions may also may be combined with logical expressions:

          $<$<VERSION_LESS:$<CXX_COMPILER_VERSION>,4.2.0>:OLD_COMPILER>

       expands to OLD_COMPILER if the CMAKE_CXX_COMPILER_VERSION is less  than
       4.2.0.

       Available informational expressions are:

       $<CONFIGURATION>
              Configuration name. Deprecated. Use CONFIG instead.

       $<CONFIG>
              Configuration name

       $<PLATFORM_ID>
              The  CMake-id  of  the platform.  See also the CMAKE_SYSTEM_NAME
              variable.

       $<C_COMPILER_ID>
              The  CMake-id  of  the  C   compiler   used.    See   also   the
              CMAKE_<LANG>_COMPILER_ID variable.

       $<CXX_COMPILER_ID>
              The   CMake-id   of   the  CXX  compiler  used.   See  also  the
              CMAKE_<LANG>_COMPILER_ID variable.

       $<C_COMPILER_VERSION>
              The  version  of  the   C   compiler   used.    See   also   the
              CMAKE_<LANG>_COMPILER_VERSION variable.

       $<CXX_COMPILER_VERSION>
              The   version   of   the   CXX  compiler  used.   See  also  the
              CMAKE_<LANG>_COMPILER_VERSION variable.

       $<TARGET_FILE:tgt>
              Full path to main file (.exe, .so.1.2, .a) where tgt is the name
              of a target.

       $<TARGET_FILE_NAME:tgt>
              Name of main file (.exe, .so.1.2, .a).

       $<TARGET_FILE_DIR:tgt>
              Directory of main file (.exe, .so.1.2, .a).

       $<TARGET_LINKER_FILE:tgt>
              File  used  to  link  (.a, .lib, .so) where tgt is the name of a
              target.

       $<TARGET_LINKER_FILE_NAME:tgt>
              Name of file used to link (.a, .lib, .so).

       $<TARGET_LINKER_FILE_DIR:tgt>
              Directory of file used to link (.a, .lib, .so).

       $<TARGET_SONAME_FILE:tgt>
              File with soname (.so.3) where tgt is the name of a target.

       $<TARGET_SONAME_FILE_NAME:tgt>
              Name of file with soname (.so.3).

       $<TARGET_SONAME_FILE_DIR:tgt>
              Directory of with soname (.so.3).

       $<TARGET_PDB_FILE:tgt>
              Full path to the linker generated program database  file  (.pdb)
              where tgt is the name of a target.

              See also the PDB_NAME and PDB_OUTPUT_DIRECTORY target properties
              and their configuration specific variants PDB_NAME_<CONFIG>  and
              PDB_OUTPUT_DIRECTORY_<CONFIG>.

       $<TARGET_PDB_FILE_NAME:tgt>
              Name of the linker generated program database file (.pdb).

       $<TARGET_PDB_FILE_DIR:tgt>
              Directory of the linker generated program database file (.pdb).

       $<TARGET_PROPERTY:tgt,prop>
              Value of the property prop on the target tgt.

              Note  that  tgt  is not added as a dependency of the target this
              expression is evaluated on.

       $<TARGET_PROPERTY:prop>
              Value of the property prop on the target on which the  generator
              expression is evaluated.

       $<INSTALL_PREFIX>
              Content  of  the  install prefix when the target is exported via
              install(EXPORT) and empty otherwise.

       $<COMPILE_LANGUAGE>
              The compile language of source  files  when  evaluating  compile
              options.  See  the  unary version for notes about portability of
              this generator expression.

OUTPUT EXPRESSIONS
       These expressions generate output, in some cases depending on an input.
       These  expressions  may be combined with other expressions for informa-
       tion or logical comparison:

          -I$<JOIN:$<TARGET_PROPERTY:INCLUDE_DIRECTORIES>, -I>

       generates a string of the entries  in  the  INCLUDE_DIRECTORIES  target
       property with each entry preceeded by -I. Note that a more-complete use
       in this situation would require first checking if the  INCLUDE_DIRECTO-
       RIES property is non-empty:

          $<$<BOOL:${prop}>:-I$<JOIN:${prop}, -I>>

       where ${prop} refers to a helper variable:

          set(prop "$<TARGET_PROPERTY:INCLUDE_DIRECTORIES>")

       Available output expressions are:

       $<0:...>
              Empty string (ignores ...)

       $<1:...>
              Content of ...

       $<JOIN:list,...>
              Joins the list with the content of ...

       $<ANGLE-R>
              A literal >. Used to compare strings which contain a > for exam-
              ple.

       $<COMMA>
              A literal ,. Used to compare strings which contain a , for exam-
              ple.

       $<SEMICOLON>
              A  literal ;. Used to prevent list expansion on an argument with
              ;.

       $<TARGET_NAME:...>
              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.

       $<LINK_ONLY:...>
              Content  of  ... except when evaluated in a link interface while
              propagating Target Usage Requirements, in which case it  is  the
              empty   string.    Intended   for   use   only   in   an  INTER-
              FACE_LINK_LIBRARIES  target  property,  perhaps  via  the   tar-
              get_link_libraries()  command, to specify private link dependen-
              cies without other usage requirements.

       $<INSTALL_INTERFACE:...>
              Content  of  ...   when   the   property   is   exported   using
              install(EXPORT), and empty otherwise.

       $<BUILD_INTERFACE:...>
              Content  of ... when the property is exported using export(), or
              when the target is used by another target in the same  buildsys-
              tem. Expands to the empty string otherwise.

       $<LOWER_CASE:...>
              Content of ... converted to lower case.

       $<UPPER_CASE:...>
              Content of ... converted to upper case.

       $<MAKE_C_IDENTIFIER:...>
              Content of ... converted to a C identifier.

       $<TARGET_OBJECTS:objLib>
              List  of  objects resulting from build of objLib. objLib must be
              an object of type OBJECT_LIBRARY.  This expression may  only  be
              used  in  the sources of add_library() and add_executable() com-
              mands.

COPYRIGHT
       2000-2015 Kitware, Inc.



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+-----------------------+
       |ATTRIBUTE TYPE |   ATTRIBUTE VALUE     |
       +---------------+-----------------------+
       |Availability   | developer/build/cmake |
       +---------------+-----------------------+
       |Stability      | Uncommitted           |
       +---------------+-----------------------+
NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source                was                downloaded                from
       http://www.cmake.org/files/v3.9/cmake-3.9.1.tar.gz

       Further information about this software can be found on the open source
       community website at http://www.cmake.org/.



3.3.2                          October 14, 2015
                                                CMAKE-GENERATOR-EXPRESSIONS(7)