Check if a C function can be linked
Checks that the
<function>is provided by libraries on the system and store the result in a
<variable>, which will be created as an internal cache variable.
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.
New in version 3.14: a ;-list of options to add to the link command.
New in version 3.1: execute quietly without messages.
CheckSymbolExists instead of this module,
for the following reasons:
check_function_exists()can't detect functions that are inlined in headers or specified as a macro.
check_function_exists()can't detect anything in the 32-bit versions of the Win32 API, because of a mismatch in calling conventions.
check_function_exists()only verifies linking, it does not verify that the function is declared in system headers.