On Wed, Jun 17, 2026 at 02:44:35PM +0100, Jonathan Wakely wrote: > On Wed, 17 Jun 2026 at 14:10, Patrick Palka <[email protected]> wrote: > > > > On Wed, 17 Jun 2026, Patrick Palka wrote: > > > > > On Mon, 8 Jun 2026, Marek Polacek wrote: > > > > > > > Bootstrapped/regtested on ppc64le-pc-linux-gnu, ok for trunk? > > > > > > > > -- >8 -- > > > > r15-2650 removed noexcept from non-const std::basic_string::data() > > > > in bits/cow_string.h, but the explicit instantiations in string-inst.cc > > > > kept their noexcept. > > > > [except.spec] says that in an explicit instantiation > > > > a noexcept-specifier may be specified, but is not required, but when it > > > > is specified, it must be the same as the exception specification of all > > > > other declarations of that function. So I think we should just remove > > > > it. > > Does GCC fail to diagnose the 'noexcept' for the COW instantiation?
Right now yes. But I have a patch for it: <https://gcc.gnu.org/pipermail/gcc-patches/2026-June/719735.html> which is how I found this. > > > > > > LGTM. Alternatively we could conditionally add the noexcept depending > > > on whether the C++11 or COW std::string is in effect but it's simpler to > > > just unconditionally omit it. > > > > > > > > > > > libstdc++-v3/ChangeLog: > > > > > > > > * src/c++17/string-inst.cc (basic_string::data): Remove noexcept. > > > > --- > > > > libstdc++-v3/src/c++17/string-inst.cc | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/libstdc++-v3/src/c++17/string-inst.cc > > > > b/libstdc++-v3/src/c++17/string-inst.cc > > > > index ac52adaa7b5..e9ef1bfd0dc 100644 > > > > --- a/libstdc++-v3/src/c++17/string-inst.cc > > > > +++ b/libstdc++-v3/src/c++17/string-inst.cc > > > > @@ -42,14 +42,14 @@ template > > > > basic_string<char>::basic_string(__sv_wrapper, const allocator_type&); > > > > template basic_string<char>::__sv_wrapper::__sv_wrapper(string_view); > > > > template string_view > > > > basic_string<char>::_S_to_string_view(string_view); > > > > template basic_string<char>::operator string_view() const noexcept; > > > > Should we also remove the noexcept here too, for consistency? > > I don't have an opinion on that, either way is fine by me. > > > > > -template char* basic_string<char>::data() noexcept; > > > > +template char* basic_string<char>::data(); > > I was wondering if we should have a comment here explaining why we > don't say noexcept, but I don't think it's likely that anybody will > try to add it back. So we don't need a comment. > > OK for trunk (with or without removing noexcept on both the string > view conversion operators). Thanks, pushed as-is. We'll give an error if they become out of sync again. Marek
