[gcc r16-4068] libstdc++/testsuite: Unpoison 'u' on s390x in names.cc test

[Patrick Palka]

https://gcc.gnu.org/g:e9f3138f38067664bae25947ebabc0e8fa223d43

commit r16-4068-ge9f3138f38067664bae25947ebabc0e8fa223d43
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Sep 23 22:41:26 2025 -0400

    libstdc++/testsuite: Unpoison 'u' on s390x in names.cc test
    
    This is the s390 counterpart to r11-7364-gd0453cf5c68b6a, and fixes the
    following names.cc failure caused by a use of a poisoned identifier.
    If we look at the corresponding upstream header[1] it's clear that the
    problematic identifier is 'u'.
    
    In file included from /usr/include/linux/types.h:5,
                     from /usr/include/linux/sched/types.h:5,
                     from /usr/include/bits/sched.h:61,
                     from /usr/include/sched.h:43,
                     from /usr/include/pthread.h:22,
                     from /usr/include/c++/14/s390x-redhat-linux/bits/gthr-default.h:35,
                     from /usr/include/c++/14/s390x-redhat-linux/bits/gthr.h:157,
                     from /usr/include/c++/14/ext/atomicity.h:35,
                     from /usr/include/c++/14/bits/ios_base.h:39,
                     from /usr/include/c++/14/streambuf:43,
                     from /usr/include/c++/14/bits/streambuf_iterator.h:35,
                     from /usr/include/c++/14/iterator:66,
                     from /usr/include/c++/14/s390x-redhat-linux/bits/stdc++.h:54,
                     from /root/rpmbuild/BUILD/gcc-14.3.1-20250617/libstdc++-v3/testsuite/17_intro/names.cc:384:
    /usr/include/asm/types.h:24: error: expected unqualified-id before '[' token
    /usr/include/asm/types.h:24: error: expected ')' before '[' token
    /root/rpmbuild/BUILD/gcc-14.3.1-20250617/libstdc++-v3/testsuite/17_intro/names.cc:101: note: to match this '('
    compiler exited with status 1
    FAIL: 17_intro/names.cc  -std=gnu++98 (test for excess errors)
    Excess errors:
    /usr/include/asm/types.h:24: error: expected unqualified-id before '[' token
    /usr/include/asm/types.h:24: error: expected ')' before '[' token
    
    [1]: https://github.com/torvalds/linux/blob/master/arch/s390/include/uapi/asm/types.h
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/17_intro/names.cc: Undefine 'u' on s390*-linux.
    
    Reviewed-by: Jonathan Wakely <jwakely@redhat.com>

Diff:
---
 libstdc++-v3/testsuite/17_intro/names.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libstdc++-v3/testsuite/17_intro/names.cc b/libstdc++-v3/testsuite/17_intro/names.cc
index e94da9defb29..befb5aad2575 100644
--- a/libstdc++-v3/testsuite/17_intro/names.cc
+++ b/libstdc++-v3/testsuite/17_intro/names.cc
@@ -286,6 +286,8 @@
 // <sys/ucontext.h> defines fpreg_t::d and fpreg_t::f
 #undef d
 #undef f
+// <asm/types.h> defines __vector128::u
+#undef u
 #endif
 
 #if defined (__linux__) && defined (__sparc__)