Re: [r16-6205 Regression] FAIL: 26_numerics/random/negative_binomial_distribution/operators/58302.cc -std=gnu++20 (test for excess errors) on Linux/x86_64

On Mon, Dec 22, 2025 at 2:53 AM Jiang, Haochen <[email protected]>
wrote:

> I got this after the commit for this test:
>
>
>
> /export/users3/haochenj/src/gcc-bisect/master/master/r16-6205/bld/x86_64-linux/32/libstdc++-v3/include/bits/random.tcc:3697:
> error: static assertion failed: irregular RNG with float precision >32
> requires __int128 support
>
> /export/users3/haochenj/src/gcc-bisect/master/master/r16-6205/bld/x86_64-linux/32/libstdc++-v3/include/bits/random.tcc:3702:
> warning: no return statement in function returning non-void [-Wreturn-type]
>
This assertion is no longer present on trunk, and was removed by the commit
I have mentioned below.

>
>
> I guess a simple target int128 check to skip the test will be safe way to
> fix the issue if nobody has committed a patch to fix it.
>
I believe that the above issues are already fixed on trunk (as Dec 17).

>
>
> Thx,
>
> Haochen
>
>
>
> *From:* Tomasz Kaminski <[email protected]>
> *Sent:* Saturday, December 20, 2025 3:44 AM
> *To:* Jiang, Haochen <[email protected]>
> *Cc:* [email protected]; [email protected]
> *Subject:* Re: [r16-6205 Regression] FAIL:
> 26_numerics/random/negative_binomial_distribution/operators/58302.cc
> -std=gnu++20 (test for excess errors) on Linux/x86_64
>
>
>
> There were many patches fixing generate_canonical merged including ones
> that landed today,
>
> and -m32 works correctly on the trunk for me. Could you please double
> check?
>
> I think most relevant would be this one:
>
> commit 9614fe95eb33f8ff783b899049f61f74373ff982
> Author: Jonathan Wakely <[email protected]>
> Date:   Wed Dec 17 18:36:36 2025 +0000
>
>     libstdc++: Fix up std::generate_canonical for 32-bit arches
>
>
>
>
> On Fri, Dec 19, 2025 at 5:26 PM Haochen Jiang <[email protected]>
> wrote:
>
> On Linux/x86_64,
>
> 837c21e1aab850126e91eee9b8944aa2baca9ad5 is the first bad commit
> commit 837c21e1aab850126e91eee9b8944aa2baca9ad5
> Author: Tomasz Kamiński <[email protected]>
> Date:   Wed Dec 17 10:32:54 2025 +0100
>
>     libstdc++: Make declaration and definition of generate_canonical
> consistent.
>
> caused
>
> FAIL: 26_numerics/random/discrete_distribution/operators/call-default.cc
> -std=gnu++20 (test for excess errors)
> FAIL:
> 26_numerics/random/negative_binomial_distribution/operators/58302.cc
> -std=gnu++20 (test for excess errors)
>
> with GCC configured with
>
> ../../gcc/configure
> --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r16-6205/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}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=26_numerics/random/discrete_distribution/operators/call-default.cc
> --target_board='unix{-m32}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=26_numerics/random/discrete_distribution/operators/call-default.cc
> --target_board='unix{-m32\ -march=cascadelake}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=26_numerics/random/negative_binomial_distribution/operators/58302.cc
> --target_board='unix{-m32}'"
> $ cd {build_dir}/x86_64-linux/libstdc++-v3/testsuite && make check
> RUNTESTFLAGS="conformance.exp=26_numerics/random/negative_binomial_distribution/operators/58302.cc
> --target_board='unix{-m32\ -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.)
>
>