[r16-1247 Regression] FAIL: g++.dg/modules/xtreme-header-8.C -std=c++26 (test for excess errors) on Linux/x86_64

[haochen.jiang]

On Linux/x86_64,

bdae7824cd9a9d27665bf1b82f60a761a9745a6a is the first bad commit
commit bdae7824cd9a9d27665bf1b82f60a761a9745a6a
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Jun 4 15:53:20 2025 +0100

    libstdc++: Optimize std::counting_semaphore for futex path

caused

FAIL: g++.dg/modules/xtreme-header-8.C module-cmi xstd (gcm.cache/xstd.gcm)
FAIL: g++.dg/modules/xtreme-header-8.C -std=c++26 (test for excess errors)

with GCC configured with

../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-1247/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="modules.exp=g++.dg/modules/xtreme-header-8.C --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="modules.exp=g++.dg/modules/xtreme-header-8.C --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="modules.exp=g++.dg/modules/xtreme-header-8.C --target_board='unix{-m64}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="modules.exp=g++.dg/modules/xtreme-header-8.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.)