CheckSymbolExists¶
Provides a macro to check if a symbol exists as a function, variable,
or macro in C.
- 
check_symbol_exists¶
- 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 CheckSourceCompiles).
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:
- CMAKE_REQUIRED_FLAGS
- string of compile command line flags. 
- CMAKE_REQUIRED_DEFINITIONS
- a ;-list of macros to define (-DFOO=bar). 
- CMAKE_REQUIRED_INCLUDES
- a ;-list of header search paths to pass to the compiler. 
- CMAKE_REQUIRED_LINK_OPTIONS
- New in version 3.14: a ;-list of options to add to the link command. 
- CMAKE_REQUIRED_LIBRARIES
- a ;-list of libraries to add to the link command. See policy - CMP0075.
- CMAKE_REQUIRED_QUIET
- New in version 3.1: execute quietly without messages. 
For example:
include(CheckSymbolExists)
# Check for macro SEEK_SET
check_symbol_exists(SEEK_SET "stdio.h" HAVE_SEEK_SET)
# Check for function fopen
check_symbol_exists(fopen "stdio.h" HAVE_FOPEN)
