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?

> >
> > 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).


> > >
> > >  #ifdef _GLIBCXX_USE_WCHAR_T
> > >  template basic_string<wchar_t>::basic_string(__sv_wrapper, const 
> > > allocator_type&);
> > >  template basic_string<wchar_t>::__sv_wrapper::__sv_wrapper(wstring_view);
> > >  template wstring_view 
> > > basic_string<wchar_t>::_S_to_string_view(wstring_view);
> > >  template basic_string<wchar_t>::operator wstring_view() const noexcept;
> > > -template wchar_t* basic_string<wchar_t>::data() noexcept;
> > > +template wchar_t* basic_string<wchar_t>::data();
> > >  #endif
> > >
> > >  _GLIBCXX_END_NAMESPACE_VERSION
> > >
> > > base-commit: 32bbd8849a550ad6f936636476c3ab9be8a58807
> > > --
> > > 2.54.0
> > >
> > >
> >
>

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