[PATCH][_GLIBCXX_DEBUG] Enhance COW basic_string checks

[François Dumont]

Gentle reminder, any chance to review it ?

On 6/15/26 07:07, François Dumont wrote:
> Hi
>
>    libstdc++: [_GLIBCXX_DEBUG] Improve COW basic_string checks
>
>     Put the __glibcxx_requires_valid_range checks at public member level
>     so that diagnostics are giving directly the invoked member name.
>
>     Add the std::_RequireInputIter constraints on members taking template
>     iterator range to avoid the "do the right thing" ambiguity without 
> the help of __is_integer.
>
>     libstdc++v3/ChangeLog:
>
>             * include/bits/cow_string.h
>             (basic_string::_M_replace): New.
>             (basic_string(_InputIterator, _InputIterator, const 
> _Alloc&): Add
>             std::_RequireInputIter constraint and 
> __glibcxx_requires_valid_constructor_range
>             check.
>             (basic_string::append(_InputIte, _InputIte): Add 
> std::_RequireInputIter
>             constraint and __glibcxx_requires_valid_range check. Call 
> _M_replace.
>             (basic_string::assign(_InputIte, _InputIte): Likewise.
>             (basic_string::insert(iterator, _InputIte, _InputIte)): 
> Likewise.
>             (basic_string::replace(iterator, iterator, _InputIte, 
> _InputIte)): Likewise.
>             [__cplusplus >= 201103L](basic_string::_S_construct): New.
>             (basic_string::_M_replace_dispatch(iterator, iterator, 
> _InputIte, _InputIte,
>             __false_type)): Remove __glibcxx_requires_valid_range check.
>             * include/debug/debug.h 
> (__glibcxx_requires_valid_constructor_range): New.
>
> Tested under Linux x86_64 with _GLIBCXX_USE_CXX11_ABI=0 and 
> _GLIBCXX_DEBUG.
>
> Note that there is a double requires-valid-range check when _M_replace 
> is being called because of the temporary basic_string instantiation.
>
> Ok to commit ?
>
> François