[Bug c++/106486] C++ warning for -Wmissing-prototypes is pure nuisance

[hpa at zytor dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106486

--- Comment #6 from H. Peter Anvin <hpa at zytor dot com> ---
Ping on this? It seems it ought to be a trivial thing to do?

The solution in Comment 3 is definitely the right one; -Wno-missing-prototypes
should be a warning (and ignored) or even an error, but -Wmissing-prototypes
just silently ignored as redundant.

Although a lot of Makefiles have CXXFLAGS, it is common enough to have
WARNFLAGS or similar to make it easier to customize warnings. If warnings are
probed by autoconf, a lot of configure scripts get it actively wrong. This
includes GNU projects, or at least used to (they might have been fixed since, I
don't know.)

-Wno-unknown-warning-option (Comment 2) is another possibility (not mutually
exclusive, either.) One can argue back and forth if "unknown" is really the
right thing here as opposed to something like -Wno-invalid-warning-option, but
it is *definitely* bizarre to have a completely unknown warning symbol be
ignored, but then have a new version of gcc suddenly start spewing warnings
over it.