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cmake-buildsystem (7)

Name

cmake-buildsystem - CMake Buildsystem Reference

Synopsis

Please see following description for synopsis

Description

CMAKE-BUILDSYSTEM(7)                 CMake                CMAKE-BUILDSYSTEM(7)



NAME
       cmake-buildsystem - CMake Buildsystem Reference

INTRODUCTION
       A  CMake-based  buildsystem is organized as a set of high-level logical
       targets.  Each target corresponds to an executable or library, or is  a
       custom  target  containing  custom  commands.  Dependencies between the
       targets are expressed in the buildsystem to determine the  build  order
       and the rules for regeneration in response to change.

BINARY TARGETS
       Executables  and  libraries  are defined using the add_executable() and
       add_library() commands.  The resulting binary  files  have  appropriate
       prefixes, suffixes and extensions for the platform targeted.  Dependen-
       cies  between   binary   targets   are   expressed   using   the   tar-
       get_link_libraries() command:

          add_library(archive archive.cpp zip.cpp lzma.cpp)
          add_executable(zipapp zipapp.cpp)
          target_link_libraries(zipapp archive)

       archive is defined as a static library -- an archive containing objects
       compiled from archive.cpp, zip.cpp, and lzma.cpp.  zipapp is defined as
       an executable formed by compiling and linking zipapp.cpp.  When linking
       the zipapp executable, the archive static library is linked in.

   Binary Executables
       The add_executable() command defines an executable target:

          add_executable(mytool mytool.cpp)

       Commands such as add_custom_command(), which generates rules to be  run
       at  build  time can transparently use an EXECUTABLE target as a COMMAND
       executable.  The buildsystem rules will ensure that the  executable  is
       built before attempting to run the command.

   Binary Library Types
   Normal Libraries
       By  default, the add_library() command defines a static library, unless
       a type is specified.  A type may be specified when using the command:

          add_library(archive SHARED archive.cpp zip.cpp lzma.cpp)

          add_library(archive STATIC archive.cpp zip.cpp lzma.cpp)

       The BUILD_SHARED_LIBS variable may be enabled to change the behavior of
       add_library() to build shared libraries by default.

       In  the context of the buildsystem definition as a whole, it is largely
       irrelevant whether particular libraries are SHARED  or  STATIC  --  the
       commands,  dependency  specifications  and  other  APIs  work similarly
       regardless of the library type.  The MODULE library type is  dissimilar
       in  that  it  is  generally  not  linked  to  --  it is not used in the
       right-hand-side of the target_link_libraries() command.  It is  a  type
       which is loaded as a plugin using runtime techniques.

          add_library(archive MODULE 7z.cpp)

   Object Libraries
       The   OBJECT  library  type  is  also  not  linked  to.  It  defines  a
       non-archival collection of object files resulting  from  compiling  the
       given  source files.  The object files collection can be used as source
       inputs to other targets:

          add_library(archive OBJECT archive.cpp zip.cpp lzma.cpp)

          add_library(archiveExtras STATIC $<TARGET_OBJECTS:archive> extras.cpp)

          add_executable(test_exe $<TARGET_OBJECTS:archive> test.cpp)

       OBJECT libraries may only be used locally as sources in  a  buildsystem
       --  they may not be installed, exported, or used in the right hand side
       of target_link_libraries().  They also may not be used as the TARGET in
       a use of the add_custom_command(TARGET) command signature.

       Although  object  libraries  may  not be named directly in calls to the
       target_link_libraries() command, they can  be  "linked"  indirectly  by
       using  an  Interface Library whose INTERFACE_SOURCES target property is
       set to name $<TARGET_OBJECTS:objlib>.

BUILD SPECIFICATION AND USAGE REQUIREMENTS
       The target_include_directories(), target_compile_definitions() and tar-
       get_compile_options() commands specify the build specifications and the
       usage requirements  of  binary  targets.   The  commands  populate  the
       INCLUDE_DIRECTORIES,  COMPILE_DEFINITIONS  and  COMPILE_OPTIONS  target
       properties  respectively,  and/or  the   INTERFACE_INCLUDE_DIRECTORIES,
       INTERFACE_COMPILE_DEFINITIONS   and   INTERFACE_COMPILE_OPTIONS  target
       properties.

       Each of the commands has a PRIVATE, PUBLIC  and  INTERFACE  mode.   The
       PRIVATE  mode  populates  only the non-INTERFACE_ variant of the target
       property and the INTERFACE mode populates only the INTERFACE_ variants.
       The  PUBLIC  mode populates both variants of the repective target prop-
       erty.  Each command may be invoked with multiple uses of each keyword:

          target_compile_definitions(archive
            PRIVATE BUILDING_WITH_LZMA
            INTERFACE USING_ARCHIVE_LIB
          )

       Note that usage requirements are not designed as a way  to  make  down-
       streams  use  particular COMPILE_OPTIONS or COMPILE_DEFINITIONS etc for
       convenience only.  The contents of the properties must be requirements,
       not merely recommendations or convenience.

       See  the Creating Relocatable Packages section of the cmake-packages(7)
       manual for discussion of additional care that must be taken when speci-
       fying usage requirements while creating packages for redistribution.

   Target Properties
       The  contents  of the INCLUDE_DIRECTORIES, COMPILE_DEFINITIONS and COM-
       PILE_OPTIONS target properties are used  appropriately  when  compiling
       the source files of a binary target.

       Entries  in  the INCLUDE_DIRECTORIES are added to the compile line with
       -I or -isystem prefixes and in the order of appearance in the  property
       value.

       Entries in the COMPILE_DEFINITIONS are prefixed with -D or /D and added
       to the compile line in an unspecified order.  The DEFINE_SYMBOL  target
       property is also added as a compile definition as a special convenience
       case for SHARED and MODULE library targets.

       Entries in the COMPILE_OPTIONS are escaped for the shell and  added  in
       the order of appearance in the property value.  Several compile options
       have special separate handling, such as POSITION_INDEPENDENT_CODE.

       The  contents  of  the  INTERFACE_INCLUDE_DIRECTORIES,   INTERFACE_COM-
       PILE_DEFINITIONS  and  INTERFACE_COMPILE_OPTIONS  target properties are
       Usage Requirements -- they specify content which consumers must use  to
       correctly  compile  and  link  with the target they appear on.  For any
       binary target, the contents of each INTERFACE_ property on each  target
       specified in a target_link_libraries() command is consumed:

          set(srcs archive.cpp zip.cpp)
          if (LZMA_FOUND)
            list(APPEND srcs lzma.cpp)
          endif()
          add_library(archive SHARED ${srcs})
          if (LZMA_FOUND)
            # The archive library sources are compiled with -DBUILDING_WITH_LZMA
            target_compile_definitions(archive PRIVATE BUILDING_WITH_LZMA)
          endif()
          target_compile_definitions(archive INTERFACE USING_ARCHIVE_LIB)

          add_executable(consumer)
          # Link consumer to archive and consume its usage requirements. The consumer
          # executable sources are compiled with -DUSING_ARCHIVE_LIB.
          target_link_libraries(consumer archive)

       Because  it  is  common to require that the source directory and corre-
       sponding build directory are  added  to  the  INCLUDE_DIRECTORIES,  the
       CMAKE_INCLUDE_CURRENT_DIR  variable  can be enabled to conveniently add
       the corresponding directories to the INCLUDE_DIRECTORIES  of  all  tar-
       gets.    The  variable  CMAKE_INCLUDE_CURRENT_DIR_IN_INTERFACE  can  be
       enabled  to  add  the   corresponding   directories   to   the   INTER-
       FACE_INCLUDE_DIRECTORIES  of all targets.  This makes use of targets in
       multiple different directories  convenient  through  use  of  the  tar-
       get_link_libraries() command.

   Transitive Usage Requirements
       The usage requirements of a target can transitively propagate to depen-
       dents.  The target_link_libraries() command has PRIVATE, INTERFACE  and
       PUBLIC keywords to control the propagation.

          add_library(archive archive.cpp)
          target_compile_definitions(archive INTERFACE USING_ARCHIVE_LIB)

          add_library(serialization serialization.cpp)
          target_compile_definitions(serialization INTERFACE USING_SERIALIZATION_LIB)

          add_library(archiveExtras extras.cpp)
          target_link_libraries(archiveExtras PUBLIC archive)
          target_link_libraries(archiveExtras PRIVATE serialization)
          # archiveExtras is compiled with -DUSING_ARCHIVE_LIB
          # and -DUSING_SERIALIZATION_LIB

          add_executable(consumer consumer.cpp)
          # consumer is compiled with -DUSING_ARCHIVE_LIB
          target_link_libraries(consumer archiveExtras)

       Because  archive  is  a  PUBLIC  dependency of archiveExtras, the usage
       requirements of it are propagated to consumer too.  Because  serializa-
       tion  is  a PRIVATE dependency of archive, the usage requirements of it
       are not propagated to consumer.

       Generally,  a  dependency  should  be  specified  in  a  use  of   tar-
       get_link_libraries() with the PRIVATE keyword if it is used by only the
       implementation of a library, and not in the header files.  If a  depen-
       dency  is  additionally used in the header files of a library (e.g. for
       class inheritance), then it should be specified as a PUBLIC dependency.
       A  dependency which is not used by the implementation of a library, but
       only by its headers should be specified  as  an  INTERFACE  dependency.
       The  target_link_libraries()  command may be invoked with multiple uses
       of each keyword:

          target_link_libraries(archiveExtras
            PUBLIC archive
            PRIVATE serialization
          )

       Usage requirements are propagated by reading the INTERFACE_ variants of
       target  properties  from  dependencies  and appending the values to the
       non-INTERFACE_ variants  of  the  operand.   For  example,  the  INTER-
       FACE_INCLUDE_DIRECTORIES  of  dependencies  is read and appended to the
       INCLUDE_DIRECTORIES of the operand.  In cases where order  is  relevant
       and    maintained,    and   the   order   resulting   from   the   tar-
       get_link_libraries() calls does not allow correct compilation,  use  of
       an  appropriate  command  to  set  the property directly may update the
       order.

       For example, if the linked libraries for a target must be specified  in
       the  order  lib1 lib2 lib3 , but the include directories must be speci-
       fied in the order lib3 lib1 lib2:

          target_link_libraries(myExe lib1 lib2 lib3)
          target_include_directories(myExe
            PRIVATE $<TARGET_PROPERTY:lib3,INTERFACE_INCLUDE_DIRECTORIES>)

       Note that care must be taken when  specifying  usage  requirements  for
       targets   which   will   be   exported   for   installation  using  the
       install(EXPORT) command.  See Creating Packages for more.

   Compatible Interface Properties
       Some target properties are required to be compatible between  a  target
       and  the interface of each dependency.  For example, the POSITION_INDE-
       PENDENT_CODE target property may specify a boolean value of  whether  a
       target should be compiled as position-independent-code, which has plat-
       form-specific consequences.   A  target  may  also  specify  the  usage
       requirement  INTERFACE_POSITION_INDEPENDENT_CODE  to  communicate  that
       consumers must be compiled as position-independent-code.

          add_executable(exe1 exe1.cpp)
          set_property(TARGET exe1 PROPERTY POSITION_INDEPENDENT_CODE ON)

          add_library(lib1 SHARED lib1.cpp)
          set_property(TARGET lib1 PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE ON)

          add_executable(exe2 exe2.cpp)
          target_link_libraries(exe2 lib1)

       Here, both exe1 and exe2 will be compiled as position-independent-code.
       lib1 will also be compiled as position-independent-code because that is
       the default setting for SHARED libraries.  If  dependencies  have  con-
       flicting, non-compatible requirements cmake(1) issues a diagnostic:

          add_library(lib1 SHARED lib1.cpp)
          set_property(TARGET lib1 PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE ON)

          add_library(lib2 SHARED lib2.cpp)
          set_property(TARGET lib2 PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE OFF)

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1)
          set_property(TARGET exe1 PROPERTY POSITION_INDEPENDENT_CODE OFF)

          add_executable(exe2 exe2.cpp)
          target_link_libraries(exe2 lib1 lib2)

       The  lib1  requirement INTERFACE_POSITION_INDEPENDENT_CODE is not "com-
       patible" with the POSITION_INDEPENDENT_CODE property of the  exe1  tar-
       get.   The  library requires that consumers are built as position-inde-
       pendent-code, while the executable specifies  to  not  built  as  posi-
       tion-independent-code, so a diagnostic is issued.

       The  lib1  and  lib2  requirements  are  not "compatible".  One of them
       requires that consumers are built as  position-independent-code,  while
       the  other  requires  that consumers are not built as position-indepen-
       dent-code.  Because exe2 links to both and  they  are  in  conflict,  a
       diagnostic is issued.

       To be "compatible", the POSITION_INDEPENDENT_CODE property, if set must
       be either the same, in a boolean sense, as the INTERFACE_POSITION_INDE-
       PENDENT_CODE  property  of  all  transitively specified dependencies on
       which that property is set.

       This property of "compatible interface requirement" may be extended  to
       other  properties by specifying the property in the content of the COM-
       PATIBLE_INTERFACE_BOOL target property.  Each specified  property  must
       be  compatible between the consuming target and the corresponding prop-
       erty with an INTERFACE_ prefix from each dependency:

          add_library(lib1Version2 SHARED lib1_v2.cpp)
          set_property(TARGET lib1Version2 PROPERTY INTERFACE_CUSTOM_PROP ON)
          set_property(TARGET lib1Version2 APPEND PROPERTY
            COMPATIBLE_INTERFACE_BOOL CUSTOM_PROP
          )

          add_library(lib1Version3 SHARED lib1_v3.cpp)
          set_property(TARGET lib1Version3 PROPERTY INTERFACE_CUSTOM_PROP OFF)

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1Version2) # CUSTOM_PROP will be ON

          add_executable(exe2 exe2.cpp)
          target_link_libraries(exe2 lib1Version2 lib1Version3) # Diagnostic

       Non-boolean properties may also participate in  "compatible  interface"
       computations.   Properties specified in the COMPATIBLE_INTERFACE_STRING
       property must be either unspecified or compare to the same string among
       all  transitively  specified dependencies. This can be useful to ensure
       that multiple  incompatible  versions  of  a  library  are  not  linked
       together through transitive requirements of a target:

          add_library(lib1Version2 SHARED lib1_v2.cpp)
          set_property(TARGET lib1Version2 PROPERTY INTERFACE_LIB_VERSION 2)
          set_property(TARGET lib1Version2 APPEND PROPERTY
            COMPATIBLE_INTERFACE_STRING LIB_VERSION
          )

          add_library(lib1Version3 SHARED lib1_v3.cpp)
          set_property(TARGET lib1Version3 PROPERTY INTERFACE_LIB_VERSION 3)

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1Version2) # LIB_VERSION will be "2"

          add_executable(exe2 exe2.cpp)
          target_link_libraries(exe2 lib1Version2 lib1Version3) # Diagnostic

       The COMPATIBLE_INTERFACE_NUMBER_MAX target property specifies that con-
       tent will be evaluated numerically and the  maximum  number  among  all
       specified will be calculated:

          add_library(lib1Version2 SHARED lib1_v2.cpp)
          set_property(TARGET lib1Version2 PROPERTY INTERFACE_CONTAINER_SIZE_REQUIRED 200)
          set_property(TARGET lib1Version2 APPEND PROPERTY
            COMPATIBLE_INTERFACE_NUMBER_MAX CONTAINER_SIZE_REQUIRED
          )

          add_library(lib1Version3 SHARED lib1_v3.cpp)
          set_property(TARGET lib1Version2 PROPERTY INTERFACE_CONTAINER_SIZE_REQUIRED 1000)

          add_executable(exe1 exe1.cpp)
          # CONTAINER_SIZE_REQUIRED will be "200"
          target_link_libraries(exe1 lib1Version2)

          add_executable(exe2 exe2.cpp)
          # CONTAINER_SIZE_REQUIRED will be "1000"
          target_link_libraries(exe2 lib1Version2 lib1Version3)

       Similarly, the COMPATIBLE_INTERFACE_NUMBER_MIN may be used to calculate
       the numeric minimum value for a property from dependencies.

       Each calculated "compatible" property value may be read in the consumer
       at generate-time using generator expressions.

       Note  that  for  each dependee, the set of properties specified in each
       compatible interface property must not intersect with the set specified
       in any of the other properties.

   Property Origin Debugging
       Because  build  specifications  can  be determined by dependencies, the
       lack of locality of code which creates  a  target  and  code  which  is
       responsible  for  setting  build  specifications may make the code more
       difficult to reason about.  cmake(1) provides a debugging  facility  to
       print  the origin of the contents of properties which may be determined
       by dependencies.  The properties which can be debugged  are  listed  in
       the CMAKE_DEBUG_TARGET_PROPERTIES variable documentation:

          set(CMAKE_DEBUG_TARGET_PROPERTIES
            INCLUDE_DIRECTORIES
            COMPILE_DEFINITIONS
            POSITION_INDEPENDENT_CODE
            CONTAINER_SIZE_REQUIRED
            LIB_VERSION
          )
          add_executable(exe1 exe1.cpp)

       In  the  case of properties listed in COMPATIBLE_INTERFACE_BOOL or COM-
       PATIBLE_INTERFACE_STRING, the  debug  output  shows  which  target  was
       responsible for setting the property, and which other dependencies also
       defined the property.  In the case  of  COMPATIBLE_INTERFACE_NUMBER_MAX
       and  COMPATIBLE_INTERFACE_NUMBER_MIN,  the debug output shows the value
       of the property from each dependency, and whether the value  determines
       the new extreme.

   Build Specification with Generator Expressions
       Build  specifications  may use generator expressions containing content
       which may be conditional or known only at generate-time.  For  example,
       the  calculated  "compatible"  value of a property may be read with the
       TARGET_PROPERTY expression:

          add_library(lib1Version2 SHARED lib1_v2.cpp)
          set_property(TARGET lib1Version2 PROPERTY
            INTERFACE_CONTAINER_SIZE_REQUIRED 200)
          set_property(TARGET lib1Version2 APPEND PROPERTY
            COMPATIBLE_INTERFACE_NUMBER_MAX CONTAINER_SIZE_REQUIRED
          )

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1Version2)
          target_compile_definitions(exe1 PRIVATE
              CONTAINER_SIZE=$<TARGET_PROPERTY:CONTAINER_SIZE_REQUIRED>
          )

       In this case, the exe1  source  files  will  be  compiled  with  -DCON-
       TAINER_SIZE=200.

       Configuration  determined  build specifications may be conveniently set
       using the CONFIG generator expression.

          target_compile_definitions(exe1 PRIVATE
              $<$<CONFIG:Debug>:DEBUG_BUILD>
          )

       The CONFIG parameter is compared case-insensitively with the configura-
       tion  being built.  In the presence of IMPORTED targets, the content of
       MAP_IMPORTED_CONFIG_DEBUG is also accounted for by this expression.

       Some buildsystems generated by cmake(1) have a predetermined build-con-
       figuration  set  in the CMAKE_BUILD_TYPE variable.  The buildsystem for
       the IDEs such as Visual Studio and Xcode are generated  independent  of
       the  build-configuration,  and  the  actual  build configuration is not
       known until build-time.  Therefore, code such as

          string(TOLOWER ${CMAKE_BUILD_TYPE} _type)
          if (_type STREQUAL debug)
            target_compile_definitions(exe1 PRIVATE DEBUG_BUILD)
          endif()

       may appear to work for Makefile based and Ninja generators, but is  not
       portable  to  IDE  generators.   Additionally,  the IMPORTED configura-
       tion-mappings are not accounted for with code like this, so  it  should
       be avoided.

       The  unary  TARGET_PROPERTY  generator expression and the TARGET_POLICY
       generator expression are evaluated with the consuming  target  context.
       This means that a usage requirement specification may be evaluated dif-
       ferently based on the consumer:

          add_library(lib1 lib1.cpp)
          target_compile_definitions(lib1 INTERFACE
            $<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>:LIB1_WITH_EXE>
            $<$<STREQUAL:$<TARGET_PROPERTY:TYPE>,SHARED_LIBRARY>:LIB1_WITH_SHARED_LIB>
            $<$<TARGET_POLICY:CMP0041>:CONSUMER_CMP0041_NEW>
          )

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1)

          cmake_policy(SET CMP0041 NEW)

          add_library(shared_lib shared_lib.cpp)
          target_link_libraries(shared_lib lib1)

       The exe1 executable will be compiled with  -DLIB1_WITH_EXE,  while  the
       shared_lib  shared library will be compiled with -DLIB1_WITH_SHARED_LIB
       and -DCONSUMER_CMP0041_NEW, because policy CMP0041 is NEW at the  point
       where the shared_lib target is created.

       The  BUILD_INTERFACE  expression wraps requirements which are only used
       when consumed from a target in the same buildsystem, or  when  consumed
       from  a  target exported to the build directory using the export() com-
       mand.  The INSTALL_INTERFACE expression wraps  requirements  which  are
       only  used  when  consumed  from  a target which has been installed and
       exported with the install(EXPORT) command:

          add_library(ClimbingStats climbingstats.cpp)
          target_compile_definitions(ClimbingStats INTERFACE
            $<BUILD_INTERFACE:ClimbingStats_FROM_BUILD_LOCATION>
            $<INSTALL_INTERFACE:ClimbingStats_FROM_INSTALLED_LOCATION>
          )
          install(TARGETS ClimbingStats EXPORT libExport ${InstallArgs})
          install(EXPORT libExport NAMESPACE Upstream::
                  DESTINATION lib/cmake/ClimbingStats)
          export(EXPORT libExport NAMESPACE Upstream::)

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 ClimbingStats)

       In this case, the  exe1  executable  will  be  compiled  with  -DClimb-
       ingStats_FROM_BUILD_LOCATION.  The exporting commands generate IMPORTED
       targets with either the INSTALL_INTERFACE or the BUILD_INTERFACE  omit-
       ted, and the *_INTERFACE marker stripped away.  A separate project con-
       suming the ClimbingStats package would contain:

          find_package(ClimbingStats REQUIRED)

          add_executable(Downstream main.cpp)
          target_link_libraries(Downstream Upstream::ClimbingStats)

       Depending on whether the ClimbingStats package was used from the  build
       location  or  the install location, the Downstream target would be com-
       piled  with  either  -DClimbingStats_FROM_BUILD_LOCATION  or   -DClimb-
       ingStats_FROM_INSTALL_LOCATION.   For more about packages and exporting
       see the cmake-packages(7) manual.

   Include Directories and Usage Requirements
       Include directories require some special consideration  when  specified
       as  usage  requirements  and when used with generator expressions.  The
       target_include_directories() command accepts both relative and absolute
       include directories:

          add_library(lib1 lib1.cpp)
          target_include_directories(lib1 PRIVATE
            /absolute/path
            relative/path
          )

       Relative  paths  are interpreted relative to the source directory where
       the command appears.  Relative paths are  not  allowed  in  the  INTER-
       FACE_INCLUDE_DIRECTORIES of IMPORTED targets.

       In  cases  where  a  non-trivial  generator  expression  is  used,  the
       INSTALL_PREFIX expression  may  be  used  within  the  argument  of  an
       INSTALL_INTERFACE expression.  It is a replacement marker which expands
       to the installation prefix when imported by a consuming project.

       Include directories usage  requirements  commonly  differ  between  the
       build-tree    and    the   install-tree.    The   BUILD_INTERFACE   and
       INSTALL_INTERFACE generator expressions can be used to  describe  sepa-
       rate  usage  requirements  based on the usage location.  Relative paths
       are allowed within the INSTALL_INTERFACE expression and are interpreted
       relative to the installation prefix.  For example:

          add_library(ClimbingStats climbingstats.cpp)
          target_include_directories(ClimbingStats INTERFACE
            $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/generated>
            $<INSTALL_INTERFACE:/absolute/path>
            $<INSTALL_INTERFACE:relative/path>
            $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/$<CONFIG>/generated>
          )

       Two convenience APIs are provided relating to include directories usage
       requirements.  The CMAKE_INCLUDE_CURRENT_DIR_IN_INTERFACE variable  may
       be enabled, with an equivalent effect to:

          set_property(TARGET tgt APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES
            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR};${CMAKE_CURRENT_BINARY_DIR}>
          )

       for  each target affected.  The convenience for installed targets is an
       INCLUDES DESTINATION component with the install(TARGETS) command:

          install(TARGETS foo bar bat EXPORT tgts ${dest_args}
            INCLUDES DESTINATION include
          )
          install(EXPORT tgts ${other_args})
          install(FILES ${headers} DESTINATION include)

       This is equivalent to appending ${CMAKE_INSTALL_PREFIX}/include to  the
       INTERFACE_INCLUDE_DIRECTORIES of each of the installed IMPORTED targets
       when generated by install(EXPORT).

       When the INTERFACE_INCLUDE_DIRECTORIES of an imported  target  is  con-
       sumed, the entries in the property are treated as SYSTEM include direc-
       tories, as if they were listed in the INTERFACE_SYSTEM_INCLUDE_DIRECTO-
       RIES  of  the dependency. This can result in omission of compiler warn-
       ings for  headers  found  in  those  directories.   This  behavior  for
       Imported  Targets  may  be  controlled with the NO_SYSTEM_FROM_IMPORTED
       target property.

       If a binary target is linked transitively to a Mac  OX  framework,  the
       Headers  directory of the framework is also treated as a usage require-
       ment.  This has the same effect as passing the framework  directory  as
       an include directory.

   Link Libraries and Generator Expressions
       Like build specifications, link libraries may be specified with genera-
       tor expression conditions.  However, as consumption of  usage  require-
       ments  is  based  on  collection  from linked dependencies, there is an
       additional limitation that the link dependencies must form a  "directed
       acyclic  graph".   That  is, if linking to a target is dependent on the
       value of a target property, that target property may not  be  dependent
       on the linked dependencies:

          add_library(lib1 lib1.cpp)
          add_library(lib2 lib2.cpp)
          target_link_libraries(lib1 PUBLIC
            $<$<TARGET_PROPERTY:POSITION_INDEPENDENT_CODE>:lib2>
          )
          add_library(lib3 lib3.cpp)
          set_property(TARGET lib3 PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE ON)

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 lib1 lib3)

       As the value of the POSITION_INDEPENDENT_CODE property of the exe1 tar-
       get is dependent on the linked libraries (lib3), and the edge of  link-
       ing  exe1 is determined by the same POSITION_INDEPENDENT_CODE property,
       the dependency graph above contains a cycle.  cmake(1) issues  a  diag-
       nostic in this case.

   Output Artifacts
       The  buildsystem  targets  created  by  the  add_library() and add_exe-
       cutable() commands create rules to create binary  outputs.   The  exact
       output location of the binaries can only be determined at generate-time
       because it can depend on the build-configuration and the  link-language
       of   linked  dependencies  etc.   TARGET_FILE,  TARGET_LINKER_FILE  and
       related expressions can be used to access the name and location of gen-
       erated  binaries.   These  expressions do not work for OBJECT libraries
       however, as there is no single file generated by such  libraries  which
       is relevant to the expressions.

       There  are three kinds of output artifacts that may be build by targets
       as detailed in the following sections.   Their  classification  differs
       between DLL platforms and non-DLL platforms.  All Windows-based systems
       including Cygwin are DLL platforms.

   Runtime Output Artifacts
       A runtime output artifact of a buildsystem target may be:

       o The executable file (e.g. .exe) of an executable  target  created  by
         the add_executable() command.

       o On DLL platforms: the executable file (e.g. .dll) of a shared library
         target created by the add_library() command with the SHARED option.

       The RUNTIME_OUTPUT_DIRECTORY and RUNTIME_OUTPUT_NAME target  properties
       may  be  used to control runtime output artifact locations and names in
       the build tree.

   Library Output Artifacts
       A library output artifact of a buildsystem target may be:

       o The loadable module file (e.g. .dll or .so) of a module library  tar-
         get created by the add_library() command with the MODULE option.

       o On non-DLL platforms: the shared library file (e.g. .so or .dylib) of
         a shared shared library target created by the  add_library()  command
         with the SHARED option.

       The  LIBRARY_OUTPUT_DIRECTORY and LIBRARY_OUTPUT_NAME target properties
       may be used to control library output artifact locations and  names  in
       the build tree.

   Archive Output Artifacts
       An archive output artifact of a buildsystem target may be:

       o The  static library file (e.g. .lib or .a) of a static library target
         created by the add_library() command with the STATIC option.

       o On DLL platforms: the import library file (e.g.  .lib)  of  a  shared
         library  target  created by the add_library() command with the SHARED
         option.

       o On DLL platforms: the import library file  (e.g.  .lib)  of  an  exe-
         cutable  target  created  by  the  add_executable()  command when its
         ENABLE_EXPORTS target property is set.

       The ARCHIVE_OUTPUT_DIRECTORY and ARCHIVE_OUTPUT_NAME target  properties
       may  be  used to control archive output artifact locations and names in
       the build tree.

   Directory-Scoped Commands
       The target_include_directories(), target_compile_definitions() and tar-
       get_compile_options()  commands  have an effect on only one target at a
       time.   The  commands  add_definitions(),   add_compile_options()   and
       include_directories() have a similar function, but operate at directory
       scope instead of target scope for convenience.

PSEUDO TARGETS
       Some target types do not represent outputs of the buildsystem, but only
       inputs  such as external dependencies, aliases or other non-build arti-
       facts.  Pseudo targets are not represented in the  generated  buildsys-
       tem.

   Imported Targets
       An  IMPORTED target represents a pre-existing dependency.  Usually such
       targets are defined by an upstream package and  should  be  treated  as
       immutable.   It  is  not  possible  to  use  an  IMPORTED target in the
       left-hand-side    of     the     target_compile_definitions(),     tar-
       get_include_directories(),     target_compile_options()     or     tar-
       get_link_libraries() commands, as that would be an  attempt  to  modify
       it.    IMPORTED   targets   are   designed  to  be  used  only  in  the
       right-hand-side of those commands.

       IMPORTED targets may have the same usage requirement  properties  popu-
       lated  as binary targets, such as INTERFACE_INCLUDE_DIRECTORIES, INTER-
       FACE_COMPILE_DEFINITIONS,       INTERFACE_COMPILE_OPTIONS,       INTER-
       FACE_LINK_LIBRARIES, and INTERFACE_POSITION_INDEPENDENT_CODE.

       The  LOCATION may also be read from an IMPORTED target, though there is
       rarely reason to do so.   Commands  such  as  add_custom_command()  can
       transparently  use  an  IMPORTED  EXECUTABLE  target  as a COMMAND exe-
       cutable.

       The scope of the definition of an  IMPORTED  target  is  the  directory
       where it was defined.  It may be accessed and used from subdirectories,
       but not from parent directories or sibling directories.  The  scope  is
       similar to the scope of a cmake variable.

       It  is also possible to define a GLOBAL IMPORTED target which is acces-
       sible globally in the buildsystem.

       See the cmake-packages(7) manual for more  on  creating  packages  with
       IMPORTED targets.

   Alias Targets
       An  ALIAS  target  is  a  name  which may be used interchangably with a
       binary target name in read-only contexts.  A primary use-case for ALIAS
       targets is for example or unit test executables accompanying a library,
       which may be part of the same buildsystem or built separately based  on
       user configuration.

          add_library(lib1 lib1.cpp)
          install(TARGETS lib1 EXPORT lib1Export ${dest_args})
          install(EXPORT lib1Export NAMESPACE Upstream:: ${other_args})

          add_library(Upstream::lib1 ALIAS lib1)

       In another directory, we can link unconditionally to the Upstream::lib1
       target, which may be an IMPORTED target from a  package,  or  an  ALIAS
       target if built as part of the same buildsystem.

          if (NOT TARGET Upstream::lib1)
            find_package(lib1 REQUIRED)
          endif()
          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 Upstream::lib1)

       ALIAS  targets  are  not  mutable, installable or exportable.  They are
       entirely local to the buildsystem description.  A name  can  be  tested
       for  whether it is an ALIAS name by reading the ALIASED_TARGET property
       from it:

          get_target_property(_aliased Upstream::lib1 ALIASED_TARGET)
          if(_aliased)
            message(STATUS "The name Upstream::lib1 is an ALIAS for ${_aliased}.")
          endif()

   Interface Libraries
       An INTERFACE target has no LOCATION and is mutable,  but  is  otherwise
       similar to an IMPORTED target.

       It  may  specify  usage requirements such as INTERFACE_INCLUDE_DIRECTO-
       RIES, INTERFACE_COMPILE_DEFINITIONS, INTERFACE_COMPILE_OPTIONS,  INTER-
       FACE_LINK_LIBRARIES, INTERFACE_SOURCES, and INTERFACE_POSITION_INDEPEN-
       DENT_CODE.  Only the INTERFACE  modes  of  the  target_include_directo-
       ries(),  target_compile_definitions(),  target_compile_options(),  tar-
       get_sources(), and target_link_libraries() commands may  be  used  with
       INTERFACE libraries.

       A primary use-case for INTERFACE libraries is header-only libraries.

          add_library(Eigen INTERFACE)
          target_include_directories(Eigen INTERFACE
            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
            $<INSTALL_INTERFACE:include/Eigen>
          )

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 Eigen)

       Here,  the  usage  requirements  from the Eigen target are consumed and
       used when compiling, but it has no effect on linking.

       Another use-case is to employ an entirely  target-focussed  design  for
       usage requirements:

          add_library(pic_on INTERFACE)
          set_property(TARGET pic_on PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE ON)
          add_library(pic_off INTERFACE)
          set_property(TARGET pic_off PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE OFF)

          add_library(enable_rtti INTERFACE)
          target_compile_options(enable_rtti INTERFACE
            $<$<OR:$<COMPILER_ID:GNU>,$<COMPILER_ID:Clang>>:-rtti>
          )

          add_executable(exe1 exe1.cpp)
          target_link_libraries(exe1 pic_on enable_rtti)

       This  way,  the  build  specification  of exe1 is expressed entirely as
       linked targets, and the complexity of compiler-specific flags is encap-
       sulated in an INTERFACE library target.

       The properties permitted to be set on or read from an INTERFACE library
       are:

       o Properties matching INTERFACE_*

       o Built-in properties matching COMPATIBLE_INTERFACE_*

       o EXPORT_NAME

       o IMPORTED

       o NAME

       o Properties matching MAP_IMPORTED_CONFIG_*

       INTERFACE libraries may be installed and exported.   Any  content  they
       refer to must be installed separately:

          add_library(Eigen INTERFACE)
          target_include_directories(Eigen INTERFACE
            $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/src>
            $<INSTALL_INTERFACE:include/Eigen>
          )

          install(TARGETS Eigen EXPORT eigenExport)
          install(EXPORT eigenExport NAMESPACE Upstream::
            DESTINATION lib/cmake/Eigen
          )
          install(FILES
              ${CMAKE_CURRENT_SOURCE_DIR}/src/eigen.h
              ${CMAKE_CURRENT_SOURCE_DIR}/src/vector.h
              ${CMAKE_CURRENT_SOURCE_DIR}/src/matrix.h
            DESTINATION include/Eigen
          )

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-BUILDSYSTEM(7)