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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/108568] New: FAILs in 17_intro/names.cc
Date: Fri, 27 Jan 2023 08:51:18 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108568

            Bug ID: 108568
           Summary: FAILs in 17_intro/names.cc
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

On gcc112 I'm seeing
FAIL: 17_intro/names.cc (test for excess errors)
FAIL: experimental/names.cc (test for excess errors)
These are because glibc < 2.19 used __unused as field member of various
structs,
including mcontext_t in sys/ucontext.h on ppc64le.
This was changed in glibc with
https://gcc.gnu.org/pipermail/libc-alpha/2013-November/045766.html
names.cc even has
#ifdef __GLIBC_PREREQ
#if ! __GLIBC_PREREQ(2, 19)
// Glibc defines this prior to 2.19
#undef __unused
#endif
#endif
for it, but it doesn't work.  The reason is that __GLIBC_PREREQ is defined =
in
<features.h> but nothing included that header before this spot (it is inclu=
ded
later
from bits/stdc++.h).
Can't it use
#if __GLIBC__ =3D=3D 1 || (__GLIBC__ =3D=3D 2 && __GLIBC_MINOR__ < 19)
instead?  Or just
#if __GLIBC__ =3D=3D 2 && __GLIBC_MINOR__ < 19
(because who knows what glibc 1 actually used, that was 1996 and already in
1997 we had glibc 2.x).=