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

["Jiang, Haochen" <haochen.jiang@intel.com>]

It is not a target specific issue, it will fail if we enabled AVX.

e.g.:

$ /export/users/haochenj/env/build_no_bootstrap_master/gcc/xgcc -B/export/users/haochenj/env/build_no_bootstrap_master/gcc/  /export/users/haochenj/src/gcc/master/gcc/testsuite/gcc.dg/gnu23-tag-4.c  -m64 -mavx   -fdiagnostics-plain-output   -std=gnu23 -S -o gnu23-tag-4.s
/export/users/haochenj/src/gcc/master/gcc/testsuite/gcc.dg/gnu23-tag-4.c: In function ‘bar’:
/export/users/haochenj/src/gcc/master/gcc/testsuite/gcc.dg/gnu23-tag-4.c:18:47: error: initialization of ‘struct g *’ from incompatible pointer type ‘struct g *’ [-Wincompatible-pointer-types]

Thx,
Haochen

> -----Original Message-----
> From: Martin Uecker <uecker@tugraz.at>
> Sent: Friday, December 22, 2023 5:39 PM
> To: gcc-regression@gcc.gnu.org; gcc-patches@gcc.gnu.org; Jiang, Haochen
> <haochen.jiang@intel.com>; Joseph Myers <joseph@codesourcery.com>
> Subject: Re: [r14-6770 Regression] FAIL: gcc.dg/gnu23-tag-4.c (test for excess
> errors) on Linux/x86_64
> 
> 
> 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.)