Check if a symbol exists as a function, variable, or macro in C++

CHECK_CXX_SYMBOL_EXISTS(<symbol> <files> <variable>)

Check that the <symbol> is available after including given header <files> and store the result in a <variable>. Specify the list of files in one argument as a semicolon-separated list. CHECK_CXX_SYMBOL_EXISTS() can be used to check in C++ files, as opposed to CHECK_SYMBOL_EXISTS(), which works only for C.

If the header files define the symbol as a macro it is considered available and assumed to work. If the header files declare the symbol as a function or variable then the symbol must also be available for linking. If the symbol is a type or enum value it will not be recognized (consider using CheckTypeSize or CheckCSourceCompiles).

The following variables may be set before calling this macro to modify the way the check is run:

CMAKE_REQUIRED_FLAGS = string of compile command line flags
CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
CMAKE_REQUIRED_INCLUDES = list of include directories
CMAKE_REQUIRED_LIBRARIES = list of libraries to link
CMAKE_REQUIRED_QUIET = execute quietly without messages