warning: unknown attribute '__nonnull__'

[andrewrk]

/nix/store/41pf3md9zgpda9kwh6rzn5kaddf7i0lp-glibc-2.40-66-dev/include/stdlib.h:1146:14: warning: unknown attribute '__nonnull__' ignored [-Wunknown-attributes]
     __THROW __nonnull ((1));
             ^
/nix/store/41pf3md9zgpda9kwh6rzn5kaddf7i0lp-glibc-2.40-66-dev/include/sys/cdefs.h:561:28: note: expanded from here
# define __nonnull(params) __attribute_nonnull__ (params)
                           ^
/nix/store/41pf3md9zgpda9kwh6rzn5kaddf7i0lp-glibc-2.40-66-dev/include/sys/cdefs.h:555:57: note: expanded from here
#  define __attribute_nonnull__(params) __attribute__ ((__nonnull__ params))
                                                        ^

Looks like this attribute can be used to help choose better pointer types.

[ehaas]

This is more of an aro issue than a translate-c issue. __nonnull__ is annoying because it can take an arbitrary number of arguments, which isn't easily handled by the existing attribute system. I've been wanting to redo that anyway, since it has a bit too much comptime metaprogramming. However, in the meantime, the easiest solution might be for us to just consume and ignore the arguments for this particular attribute, since doing so would not affect correctness - only some warnings from using NULL directly as an argument, and some optimizations.