[Bug c/79677] Weird handling of -Werror=

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79677

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Orion Poplawski from comment #5)
> With gcc 7.0.1-0.10.fc26 I'm starting to see errors like:
> 
> cc1plus: error: -Wformat-security ignored without -Wformat
> [-Werror=format-security]
> 
> If this is intended, we're going to need to fix redhat-rpm-config to change:
> 
> %__global_compiler_flags -O2 -g -pipe -Wall -Werror=format-security
> -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
> --param=ssp-buffer-size=4 -grecord-gcc-switches %{_hardened_cflags}
> 
> to add -Wformat.

Well, -Wformat is implied by -Wall, so it must be packages doing -Wno-format or
similar.  -Wformat -Wformat-security -Wno-format used to warn in the past,
-Wformat -Werror=format-security -Wno-format used to be quite due to a bug, but
now errors out.
We have one instance of this problem in gcc too:
AS_IF([test $enable_build_format_warnings = no],
      [wf_opt=-Wno-format],[wf_opt=])
Guess we want there:
AS_IF([test $enable_build_format_warnings = no],
      [wf_opt="-Wno-format -Wno-format-security -Wno-format-y2k
-Wno-format-extra-args -Wno-format-zero-length
-Wno-format-nonliteral"],[wf_opt=])