https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120997
--- Comment #5 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:a72d0e1a8bf0770ddf1d8d0ebe589f92a4fab4ef commit r16-2152-ga72d0e1a8bf0770ddf1d8d0ebe589f92a4fab4ef Author: Jonathan Wakely <jwak...@redhat.com> Date: Tue Jul 8 14:56:39 2025 +0100 libstdc++: Do not use list-initialization in std::span members [PR120997] As the bug report shows, for span<const bool> the return statements of the form `return {data(), count};` will use the new C++26 constructor, span(initializer_list<element_type>). Although the conversions from data() to bool and count to bool are narrowing and should be ill-formed, in system headers the narrowing diagnostics are suppressed. In any case, even if the compiler diagnosed them as ill-formed, we still don't want the initializer_list constructor to be used. We want to use the span(element_type*, size_t) constructor instead. Replace the braced-init-list uses with S(data(), count) where S is the correct return type. We need to make similar changes in the C++26 working draft, which will be taken care of via an LWG issue. libstdc++-v3/ChangeLog: PR libstdc++/120997 * include/std/span (span::first, span::last, span::subspan): Do not use braced-init-list for return statements. * testsuite/23_containers/span/120997.cc: New test.
