[PATCH] libstdc++: constexpr flat_set and flat_multiset

[Yuao Ma]

On Fri, Dec 19, 2025 at 8:14 PM Tomasz Kaminski <tkaminsk@redhat.com> wrote:
>
> This commit causes failures with -D_GLIBCXX_DEBUG for flat_set.cc.
> This is caused by the fact that _Safe_iterator functions used in preconditions checks
> for lower_bound/uper_bound e.t.c. are not constexpr. The __gnu_debug;:__base,
> are trivial to fix, but we are __can_advance.
>

Thanks for the quick fix, and sorry for the regression. Going forward,
I’ll test with --target_board='unix{-D_GLIBCXX_DEBUG=0,-D_GLIBCXX_DEBUG=1}'
to ensure compatibility with both normal and debug modes.