Re: [RFC PATCH 4/4] ui/cocoa: Ignore 'initializer overrides' warnings

[Philippe Mathieu-Daudé]

On 15/2/22 14:45, Peter Maydell wrote:
> On Tue, 15 Feb 2022 at 13:18, Christian Schoenebeck
> <qemu_oss@crudebyte.com> wrote:
> > On Dienstag, 15. Februar 2022 13:06:25 CET Philippe Mathieu-Daudé via wrote:
> > > We globally ignore the 'initializer overrides' warnings in C code
> > > since commit c1556a812a ("configure: Disable (clang)
> > > initializer-overrides warnings"). Unfortunately the ${gcc_flags}
> > > variable is not propagated to Objective-C flags ($OBJCFLAGS).
> > > Instead of reworking the configure script to test all supported
> > > C flags in Objective-C and sanitize them, ignore the warning
> > > locally with the GCC diagnostic #pragma (Clang ignores it).
> > >
> > > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > > ---

> The warning is useful in the pure-standard-C world where there
> is no such thing as the "range initialization" syntax. In that
> case trying to initialize the same array member twice is very
> likely a bug. However, if you use range initialization then
> the pattern "initialize a range first, then override some specific
> members within it" is very common and the warning is incorrect here.
> We use and like the range-initialization syntax, and so we disable
> the -Winitializer-overrides warnings. The bug here is just that
> we are incorrectly failing to apply the warning flags we use
> for C code when we compile ObjC files.

Yes, but simply adding nowarn_flags to objc_args isn't enough, we
need to filter the flags similarly to what is done in C to avoid:

[7/373] Compiling Objective-C object libcommon.fa.p/audio_coreaudio.m.o
warning: unknown warning option '-Wold-style-declaration'; did you mean 
'-Wout-of-line-declaration'? [-Wunknown-warning-option]
warning: unknown warning option '-Wimplicit-fallthrough=2'; did you mean 
'-Wimplicit-fallthrough'? [-Wunknown-warning-option]
2 warnings generated.
[34/373] Compiling Objective-C object libcommon.fa.p/ui_cocoa.m.o
warning: unknown warning option '-Wold-style-declaration'; did you mean 
'-Wout-of-line-declaration'? [-Wunknown-warning-option]
warning: unknown warning option '-Wimplicit-fallthrough=2'; did you mean 
'-Wimplicit-fallthrough'? [-Wunknown-warning-option]
2 warnings generated.