[Bug c++/91187] Is it possible to make -Wzero-as-null-pointer-constant learn about extern "C"?

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91187

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #2)
> maybe try putting #pragma GCC system_header in your headers? idk

Please no, that's for marking a header as part of "the implementation" not a
diagnostic-suppression mechanism for user code!