Re: [r14-6770 Regression] FAIL: gcc.dg/gnu23-tag-4.c (test for excess errors) on Linux/x86_64

[Martin Uecker <uecker@tugraz.at>]

Hm, this is weird, as it really seems to depend on the
-march=....  So if there is really a difference
between those structs which make them incompatible on
some archs, we should not consider them to be
compatible in general.

struct g { int a[n]; int b; } *y;
{ struct g { int a[4]; int b; } *y2 = y; }

But I do not see what could go wrong here as
sizeof / alignment is the same for n = 4.  So there
is something else I missed....



Am Freitag, dem 22.12.2023 um 05:07 +0800 schrieb haochen.jiang:
> On Linux/x86_64,
> 
> 23fee88f84873b0b8b41c8e5a9b229d533fb4022 is the first bad commit
> commit 23fee88f84873b0b8b41c8e5a9b229d533fb4022
> Author: Martin Uecker <uecker@tugraz.at>
> Date:   Tue Aug 15 14:58:32 2023 +0200
> 
>     c23: tag compatibility rules for struct and unions
> 
> caused
> 
> FAIL: gcc.dg/gnu23-tag-4.c (test for excess errors)
> 
> with GCC configured with
> 
> ../../gcc/configure --prefix=/export/users/haochenj/src/gcc-bisect/master/master/r14-6770/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap
> 
> To reproduce:
> 
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/gnu23-tag-4.c --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check RUNTESTFLAGS="dg.exp=gcc.dg/gnu23-tag-4.c --target_board='unix{-m64\ -march=cascadelake}'"
> 
> (Please do not reply to this email, for question about this report, contact me at haochen dot jiang at intel.com.)
> (If you met problems with cascadelake related, disabling AVX512F in command line might save that.)
> (However, please make sure that there is no potential problems with AVX512.)