Hi Simon, What is the use of these macros gl_WARN_COMPLEMENT, gl_WARN_SUPPORTED? They are not documented, and you haven't said what they are good for.
In particular, I don't see what anyone can do with the list of all GCC supported warning options. While -Wall is widely applicable, most other warnings is specific to a particular kind of coding style or kind of application area. For example, - -Wunused is useful when the program has no function types, but produces useless warnings when callbacks and function types are used, - -Wfloat-equal is useful when you write numerical approximation algorithms, but produces useless warnings for implementations of basic functions like ceill or roundl, - -Waggregate-return is useful for programs that want portability to pre-ANSI-C compilers (!), but produces useless warnings for code that is nowadays considered normal, - -Wlong-long is useful for programs that want portability to 1995 compilers, but produces warnings for programs which require 64-bit integers (which gnulib does). Bruno