try_compile — CMake 3.24.4 Documentation (original) (raw)

Contents

• try_compile
  • Try Compiling Whole Projects
  • Try Compiling Source Files
  • Other Behavior Settings

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.

Changed in version 3.24: CMake variables describing platform settings, and those listed by theCMAKE_TRY_COMPILE_PLATFORM_VARIABLES variable, are propagated into the project's build configuration. See policy CMP0137. Previously this was only done by thesource file signature.

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>...

New in version 3.14.

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>

New in version 3.8.

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

<LANG>_STANDARD_REQUIRED <bool>

New in version 3.8.

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

<LANG>_EXTENSIONS <bool>

New in version 3.8.

Specify the C_EXTENSIONS, CXX_EXTENSIONS,OBJC_EXTENSIONS, OBJCXX_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.

Other Behavior Settings¶

Changed in version 3.14: If CMP0083 is set to NEW, then in order to obtain correct behavior at link time, the check_pie_supported() command from theCheckPIESupported module must be called before using thetry_compile() command.

The current settings of CMP0065 and CMP0083 are propagated through to the generated test project.

Set the CMAKE_TRY_COMPILE_CONFIGURATION variable to choose a build configuration.

New in version 3.6: Set the CMAKE_TRY_COMPILE_TARGET_TYPE variable to specify the type of target used for the source file signature.

New in version 3.6: Set the CMAKE_TRY_COMPILE_PLATFORM_VARIABLES variable to specify variables that must be propagated into the test project. This variable is meant for use only in toolchain files and is only honored by thetry_compile() command for the source files form, not when given a whole project.

Changed in version 3.14: For the [Green Hills MULTI](../generator/Green%20Hills%20MULTI.html#generator:Green Hills MULTI "Green Hills MULTI") generator the GHS toolset and target system customization cache variables are also propagated into the test project.