[Bug c/67854] Missing diagnostic for passing bool to va_arg

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67854

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
I wonder if this is yet another issue with macros from system headers 
(bool being defined in a system header to expand to _Bool) ... maybe we 
need a systematic review of diagnostic locations in the C-family front 
ends to identify such cases where the diagnostic relates to a property of 
the use of the (type / expression) macro from a system header, not to a 
property of that (type / expression) itself, and so system-header 
suppression should only apply if the use itself is in a system header.