Provides a macro to check if a symbol exists as a function, variable, or macro in C.

check_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. <variable> will be created as an internal cache variable.

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 (so intrinsics may not be detected). If the symbol is a type, enum value, or intrinsic it will not be recognized (consider using CheckTypeSize or CheckCSourceCompiles). If the check needs to be done in C++, consider using CheckCXXSymbolExists instead.

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

string of compile command line flags.
a ;-list of macros to define (-DFOO=bar).
a ;-list of header search paths to pass to the compiler.
a ;-list of options to add to the link command.
a ;-list of libraries to add to the link command. See policy CMP0075.
execute quietly without messages.