try_run

Try compiling and then running some code.

Try Compiling and Running Source Files

try_run(<runResultVar> <compileResultVar>
        [SOURCES_TYPE <type>]
        <SOURCES <srcfile...>                 |
         SOURCE_FROM_CONTENT <name> <content> |
         SOURCE_FROM_VAR <name> <var>         |
         SOURCE_FROM_FILE <name> <path>       >...
        [LOG_DESCRIPTION <text>]
        [NO_CACHE]
        [NO_LOG]
        [CMAKE_FLAGS <flags>...]
        [COMPILE_DEFINITIONS <defs>...]
        [LINK_OPTIONS <options>...]
        [LINK_LIBRARIES <libs>...]
        [COMPILE_OUTPUT_VARIABLE <var>]
        [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
        [<LANG>_STANDARD <std>]
        [<LANG>_STANDARD_REQUIRED <bool>]
        [<LANG>_EXTENSIONS <bool>]
        [RUN_OUTPUT_VARIABLE <var>]
        [RUN_OUTPUT_STDOUT_VARIABLE <var>]
        [RUN_OUTPUT_STDERR_VARIABLE <var>]
        [WORKING_DIRECTORY <var>]
        [ARGS <args>...]
        )

Added in version 3.25.

Try building an executable from one or more source files. Build success returns TRUE and build failure returns FALSE in <compileResultVar>. If the build succeeds, this runs the executable and stores the exit code in <runResultVar>. If the executable was built, but failed to run, then <runResultVar> will be set to FAILED_TO_RUN. See command try_compile() for documentation of options common to both commands, and for information on how the test project is constructed to build the source file.

One or more source files must be provided. Additionally, one of SOURCES and/or SOURCE_FROM_* must precede other keywords.

Added in version 3.26: This command records a configure-log try_run event if the NO_LOG option is not specified.

This command supports an alternate signature for CMake older than 3.25. The signature above is recommended for clarity.

try_run(<runResultVar> <compileResultVar>
        <bindir> <srcfile|SOURCES srcfile...>
        [CMAKE_FLAGS <flags>...]
        [COMPILE_DEFINITIONS <defs>...]
        [LINK_OPTIONS <options>...]
        [LINK_LIBRARIES <libs>...]
        [LINKER_LANGUAGE <lang>]
        [COMPILE_OUTPUT_VARIABLE <var>]
        [COPY_FILE <fileName> [COPY_FILE_ERROR <var>]]
        [<LANG>_STANDARD <std>]
        [<LANG>_STANDARD_REQUIRED <bool>]
        [<LANG>_EXTENSIONS <bool>]
        [RUN_OUTPUT_VARIABLE <var>]
        [OUTPUT_VARIABLE <var>]
        [WORKING_DIRECTORY <var>]
        [ARGS <args>...]
        )

Options

The options specific to try_run are:

COMPILE_OUTPUT_VARIABLE <var>

Report the compile step build output in a given variable.

OUTPUT_VARIABLE <var>

Report the compile build output and the output from running the executable in the given variable. This option exists for legacy reasons and is only supported by the old try_run signature. Prefer COMPILE_OUTPUT_VARIABLE and RUN_OUTPUT_VARIABLE instead.

RUN_OUTPUT_VARIABLE <var>

Report the output from running the executable in a given variable.

RUN_OUTPUT_STDOUT_VARIABLE <var>

Added in version 3.25.

Report the output of stdout from running the executable in a given variable.

RUN_OUTPUT_STDERR_VARIABLE <var>

Added in version 3.25.

Report the output of stderr from running the executable in a given variable.

WORKING_DIRECTORY <var>

Added in version 3.20.

Run the executable in the given directory. If no WORKING_DIRECTORY is specified, the executable will run in <bindir> or the current build directory.

ARGS <args>...

Additional arguments to pass to the executable when running it.

Other Behavior Settings

Set variable CMAKE_TRY_COMPILE_CONFIGURATION to choose a build configuration:

  • For multi-config generators, this selects which configuration to build.

  • For single-config generators, this sets CMAKE_BUILD_TYPE in the test project.

Behavior when Cross Compiling

Added in version 3.3: Use CMAKE_CROSSCOMPILING_EMULATOR when running cross-compiled binaries.

When cross compiling, the executable compiled in the first step usually cannot be run on the build host. The try_run command checks the CMAKE_CROSSCOMPILING variable to detect whether CMake is in cross-compiling mode. If that is the case, it will still try to compile the executable, but it will not try to run the executable unless the CMAKE_CROSSCOMPILING_EMULATOR variable is set. Instead it will create cache variables which must be filled by the user or by presetting them in some CMake script file to the values the executable would have produced if it had been run on its actual target platform. These cache entries are:

<runResultVar>

Exit code if the executable were to be run on the target platform.

<runResultVar>__TRYRUN_OUTPUT

Output from stdout and stderr if the executable were to be run on the target platform. This is created only if the RUN_OUTPUT_VARIABLE or OUTPUT_VARIABLE option was used.

In order to make cross compiling your project easier, use try_run only if really required. If you use try_run, use the RUN_OUTPUT_STDOUT_VARIABLE, RUN_OUTPUT_STDERR_VARIABLE, RUN_OUTPUT_VARIABLE or OUTPUT_VARIABLE options only if really required. Using them will require that when cross-compiling, the cache variables will have to be set manually to the output of the executable. You can also "guard" the calls to try_run with an if() block checking the CMAKE_CROSSCOMPILING variable and provide an easy-to-preset alternative for this case.