Re: [PATCH v5 03/16] tests/fp/berkeley-testfloat-3: Ignore ignored #pragma directives

[Peter Maydell]

On Mon, 14 Feb 2022 at 18:56, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> Since we already use -Wno-unknown-pragmas, we can also use
> -Wno-ignored-pragmas. This silences hundred of warnings using
> clang 13 on macOS Monterey:
>
>   [409/771] Compiling C object 
> tests/fp/libtestfloat.a.p/berkeley-testfloat-3_source_test_az_f128_rx.c.o
>   ../tests/fp/berkeley-testfloat-3/source/test_az_f128_rx.c:49:14: warning: 
> '#pragma FENV_ACCESS' is not supported on this target - ignored 
> [-Wignored-pragmas]
>   #pragma STDC FENV_ACCESS ON
>                ^
>   1 warning generated.
>

GCC doesn't know about -Wignored-pragmas, so this change is relying on
the GCC "ignore a -Wno-something that this gcc doesn't recognize
if we wouldn't otherwise be complaining about something" behaviour.
I forget which GCC version that was introduced in... (This is why
configure has the cc_has_warning_flag() test before it tries to
use a warning/warning-suppression option.)

-- PMM