Re: [PATCH] Testsuite, LTO: silence warning to make test pass on Darwin

[Richard Biener <richard.guenther@gmail.com>]

On Sun, Aug 20, 2023 at 12:24 PM FX Coudert via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> Hi,
>
> On darwin (both x86_64-apple-darwin and aarch64-apple-darwin) we see the following test failure:
>
> FAIL: gcc.dg/lto/20091013-1 c_lto_20091013-1_2.o assemble, -fPIC -r -nostdlib -O2 -flto
>
> which is due to this extra warning:
>
> In function 'fontcmp',
>     inlined from 'find_in_cache' at /tmp/gcc-darwin-arm64/gcc/testsuite/gcc.dg/lto/20091013-1_2.c:140:13,
>     inlined from 'WineEngCreateFontInstance' at /tmp/gcc-darwin-arm64/gcc/testsuite/gcc.dg/lto/20091013-1_2.c:160:15:
> /tmp/gcc-darwin-arm64/gcc/testsuite/gcc.dg/lto/20091013-1_2.c:107:8: warning: 'memcmp' specified bound 4 exceeds source size 0 [-Wst
> ringop-overread]
> /tmp/gcc-darwin-arm64/gcc/testsuite/gcc.dg/lto/20091013-1_2.c: In function 'WineEngCreateFontInstance':
> /tmp/gcc-darwin-arm64/gcc/testsuite/gcc.dg/lto/20091013-1_2.c:66:20: note: source object allocated here
>
> Now, the main file for the test has:
>
> /* { dg-extra-ld-options "-flinker-output=nolto-rel -Wno-stringop-overread" } */
>
> and I believe the intent of -Wno-stringop-overread is to silence this warning, but that only applies to the linker, and the warning on darwin is produced by the compiler (in addition to the linker). Adding the flag to the compilation of the source file makes the test pass on darwin.

In the end this is because darwin is -ffat-lto-objects and not using
the linker plugin(?)

> OK to commit?

OK.

Thanks,
Richard.

> FX
>
>