Re: [r16-4421 Regression] FAIL: std/ranges/adaptors/93978.cc -std=gnu++26 (test for excess errors) on Linux/x86_64

Thank you for the report, I believe the issues are already fixed on trunk
by:
commit ec331001eaa1e42c6ff9536fa51aeaf2a1c86a6a
Author:     Luc Grosheintz <[email protected]>
AuthorDate: Tue Oct 14 17:16:55 2025 +0200
Commit:     Tomasz Kamiński <[email protected]>
CommitDate: Tue Oct 14 17:40:11 2025 +0200

    libstdc++: Remove unused local type alias <format>.

    After r16-4421-g59cabe08b57a26 the local type alias _String isn't used
    anymore and therefore causes warnings when building the tests with
    `-Wall -Wextra`.

Could you please confirm?
Regards,
Tomasz

On Thu, Oct 16, 2025 at 4:05 AM Jiang, Haochen <[email protected]>
wrote:

> On Linux/x86_64,
>
> 59cabe08b57a262d5d7d041515889a012189c908 is the first bad commit
> commit 59cabe08b57a262d5d7d041515889a012189c908
> Author: Tomasz KamiÅ"ski <[email protected]>
> Date:   Tue Jul 8 18:50:50 2025 +0200
>
>     libstdc++: Implement _Escaping_sink to avoid construction of string
>
> caused
>
> FAIL: g++.dg/warn/uninit-pr105562.C  -std=gnu++26 (test for excess errors)
> FAIL: g++.dg/warn/Wstringop-overflow-6.C  -std=gnu++26 (test for excess
> errors)
> FAIL: g++.old-deja/g++.robertl/eb73.C  -std=gnu++26 (test for excess
> errors)
> FAIL: std/ranges/adaptors/93978.cc  -std=gnu++26 (test for excess errors)
>
> with GCC configured with
>
> ../../gcc/configure
> --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-4421/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=g++.dg/warn/uninit-pr105562.C
> --target_board='unix{-m32}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/uninit-pr105562.C
> --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/uninit-pr105562.C
> --target_board='unix{-m64}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/uninit-pr105562.C
> --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/Wstringop-overflow-6.C
> --target_board='unix{-m32}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/Wstringop-overflow-6.C
> --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/Wstringop-overflow-6.C
> --target_board='unix{-m64}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="dg.exp=g++.dg/warn/Wstringop-overflow-6.C
> --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="old-deja.exp=g++.old-deja/g++.robertl/eb73.C
> --target_board='unix{-m32}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="old-deja.exp=g++.old-deja/g++.robertl/eb73.C
> --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="old-deja.exp=g++.old-deja/g++.robertl/eb73.C
> --target_board='unix{-m64}'"
> $ cd {build_dir}/gcc && make check
> RUNTESTFLAGS="old-deja.exp=g++.old-deja/g++.robertl/eb73.C
> --target_board='unix{-m64\ -march=cascadelake}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=std/ranges/adaptors/93978.cc
> --target_board='unix{-m32}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=std/ranges/adaptors/93978.cc
> --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=std/ranges/adaptors/93978.cc
> --target_board='unix{-m64}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=std/ranges/adaptors/93978.cc
> --target_board='unix{-m64\ -march=cascadelake}'"
>
> (Please directly reply to this email for question about this report.)
> (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.)
>
>