try_compile — CMake 3.14.7 Documentation (original) (raw)

Contents

Try building some code.

Try Compiling Whole Projects

try_compile( [] [CMAKE_FLAGS ...] [OUTPUT_VARIABLE ])

Try building a project. The success or failure of the try_compile, i.e. TRUE or FALSE respectively, is returned in <resultVar>.

In this form, <srcdir> should contain a complete CMake project with aCMakeLists.txt file and all sources. The <bindir> and <srcdir>will not be deleted after this command is run. Specify <targetName> to build a specific target instead of the all or ALL_BUILD target. See below for the meaning of other options.

Try Compiling Source Files

try_compile( <srcfile|SOURCES srcfile...> [CMAKE_FLAGS ...] [COMPILE_DEFINITIONS ...] [LINK_OPTIONS ...] [LINK_LIBRARIES ...] [OUTPUT_VARIABLE ] [COPY_FILE [COPY_FILE_ERROR ]] [_STANDARD ] [_STANDARD_REQUIRED ] [_EXTENSIONS ] )

Try building an executable or static library from one or more source files (which one is determined by the CMAKE_TRY_COMPILE_TARGET_TYPEvariable). The success or failure of the try_compile, i.e. TRUE orFALSE respectively, is returned in <resultVar>.

In this form, one or more source files must be provided. IfCMAKE_TRY_COMPILE_TARGET_TYPE is unset or is set to EXECUTABLE, the sources must include a definition for main and CMake will create aCMakeLists.txt file to build the source(s) as an executable. If CMAKE_TRY_COMPILE_TARGET_TYPE is set to STATIC_LIBRARY, a static library will be built instead and no definition for main is required. For an executable, the generated CMakeLists.txt file would contain something like the following:

add_definitions() include_directories(${INCLUDE_DIRECTORIES}) link_directories(${LINK_DIRECTORIES}) add_executable(cmTryCompileExec ...) target_link_options(cmTryCompileExec PRIVATE ) target_link_libraries(cmTryCompileExec ${LINK_LIBRARIES})

The options are:

CMAKE_FLAGS <flags>...

Specify flags of the form -DVAR:TYPE=VALUE to be passed to the cmake command-line used to drive the test build. The above example shows how values for variablesINCLUDE_DIRECTORIES, LINK_DIRECTORIES, and LINK_LIBRARIESare used.

COMPILE_DEFINITIONS <defs>...

Specify -Ddefinition arguments to pass to add_definitions()in the generated test project.

COPY_FILE <fileName>

Copy the built executable or static library to the given <fileName>.

COPY_FILE_ERROR <var>

Use after COPY_FILE to capture into variable <var> any error message encountered while trying to copy the file.

LINK_LIBRARIES <libs>...

Specify libraries to be linked in the generated project. The list of libraries may refer to system libraries and toImported Targets from the calling project.

If this option is specified, any -DLINK_LIBRARIES=... value given to the CMAKE_FLAGS option will be ignored.

LINK_OPTIONS <options>...

Specify link step options to pass to target_link_options() or to set the STATIC_LIBRARY_OPTIONS target property in the generated project, depending on the CMAKE_TRY_COMPILE_TARGET_TYPE variable.

OUTPUT_VARIABLE <var>

Store the output from the build process in the given variable.

<LANG>_STANDARD <std>

Specify the C_STANDARD, CXX_STANDARD, or CUDA_STANDARD target property of the generated project.

<LANG>_STANDARD_REQUIRED <bool>

Specify the C_STANDARD_REQUIRED,CXX_STANDARD_REQUIRED, or CUDA_STANDARD_REQUIREDtarget property of the generated project.

<LANG>_EXTENSIONS <bool>

Specify the C_EXTENSIONS, CXX_EXTENSIONS, or CUDA_EXTENSIONS target property of the generated project.

In this version all files in <bindir>/CMakeFiles/CMakeTmp will be cleaned automatically. For debugging, --debug-trycompile can be passed to cmake to avoid this clean. However, multiple sequentialtry_compile operations reuse this single output directory. If you use--debug-trycompile, you can only debug one try_compile call at a time. The recommended procedure is to protect all try_compile calls in your project by if(NOT DEFINED <resultVar>) logic, configure with cmake all the way through once, then delete the cache entry associated with the try_compile call of interest, and then re-run cmake again with--debug-trycompile.