# CheckCXXSourceCompiles

Check if given C++ source compiles and links into an executable.

check_cxx_source_compiles

      check_cxx_source_compiles(<code> <resultVar>
                                [FAIL_REGEX <regex1> [<regex2>...]])

  Check that the source supplied in `<code>` can be compiled as a C++ source file and linked as an executable (so it must contain at least a `main()` function). The result will be stored in the internal cache variable specified by `<resultVar>`, with a boolean true value for success and boolean false for failure. If `FAIL_REGEX` is provided, then failure is determined by checking if anything in the output matches any of the specified regular expressions.

  The check is only performed once, with the result cached in the variable named by `<resultVar>`. Every subsequent CMake run will reuse this cached value rather than performing the check again, even if the `<code>` changes. In order to force the check to be re-evaluated, the variable named by `<resultVar>` must be manually removed from the cache.

  The compile and link commands can be influenced by setting any of the following variables prior to calling `check_cxx_source_compiles()`:

> `CMAKE_REQUIRED_FLAGS`

>   String of additional flags to pass to the compiler. The string must be space-delimited--a ;-list will not work. The contents of `CMAKE_<LANG>_FLAGS` and its associated configuration-specific variable are automatically added to the compiler command before the contents of `CMAKE_REQUIRED_FLAGS`.

> `CMAKE_REQUIRED_DEFINITIONS`

>   A ;-list of compiler definitions of the form `-DFOO` or `-DFOO=bar`. A definition for the name specified by `<resultVar>` will also be added automatically.

> `CMAKE_REQUIRED_INCLUDES`

>   A ;-list of header search paths to pass to the compiler. These will be the only header search paths used--the contents of the `INCLUDE_DIRECTORIES` directory property will be ignored.

> `CMAKE_REQUIRED_LINK_OPTIONS`

>   New in version 3.14.

>   A ;-list of options to add to the link command (see `try_compile()` for further details).

> `CMAKE_REQUIRED_LIBRARIES`

>   A ;-list of libraries to add to the link command. These can be the name of system libraries or they can be Imported Targets (see `try_compile()` for further details).

> `CMAKE_REQUIRED_QUIET`

>   New in version 3.1.

>   If this variable evaluates to a boolean true value, all status messages associated with the check will be suppressed.