On Tue, 21 Jul 2026 at 07:43, Jonathan Wakely <[email protected]> wrote:
>
> On Tue, 21 Jul 2026 at 05:57, François Dumont <[email protected]> wrote:
> >
> > Here is the new commit message:
> >
> > 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 culprit member name.
> >
> > Add the std::_RequireInputIter constraints on members taking template
> > iterator range to avoid the "do the right thing" ambiguity.
> >
> > 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.
> >
> > On 7/6/26 22:42, Jonathan Wakely wrote:
> > > On Mon, 15 Jun 2026 at 07:07 +0200, 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
> > >
> > > Please fix the line-wrapping here. Try to keep the lines to < 72
> > > characters so that when indented by 'git log' they fit below 80.
> > >
> > >> 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.
> > >
> > > Did you test C++98 as well as the default -std modes?
> >
> > I hadn't but now did, ex:
> >
> > In function:
> > std::basic_string<_CharT, _Traits, _Alloc>& std::basic_string<_CharT,
> > _Traits, _Alloc>::append(_InputIterator, _InputIterator) [with
> > _InputIterator = gnu_debug::_Safe_iterator<gnu_cxx::
> > normal_iterator<char*, std::vector<char, std::allocator<char> > >,
> > std::
> > debug::vector<char>, std::random_access_iterator_tag>; _CharT = char;
> > _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]
> >
> > Error: function requires a valid iterator range [first, last).
> >
> > Objects involved in the operation:
> > iterator "first" @ 0x7ffc9027e5a0 {
> > type = gnu_cxx::normal_iterator<char*, std::vector<char,
> > std::allocator<char> > > (mutable iterator);
> > state = dereferenceable;
> > references sequence with type 'std::debug::vector<char,
> > std::allocator<char> >' @ 0x7ffc9027e750
> > }
> > iterator "last" @ 0x7ffc9027e600 {
> > type = gnu_cxx::normal_iterator<char*, std::vector<char,
> > std::allocator<char> > > (mutable iterator);
> > state = dereferenceable;
> > references sequence with type 'std::debug::vector<char,
> > std::allocator<char> >' @ 0x7ffc9027e750
> > }
> > XFAIL: 21_strings/basic_string/debug/append_neg.cc -std=gnu++98
> > execution test
> >
> > >
> > > Doesn't this require new symbols to be exported by the linker script?
> > >
> > I don't think so. Maybe you had in mind the
> > __gnu_debug::__check_valid_range but that's a template function
> > implemented inline.
>
> You've added a new member function, basic_string::_M_replace. Why
> doesn't that need to be exported from the shared library?
>
> Why don't the changes to the signature of basic_string::assign and
> basic_string::append change the exported symbols?
As expected, 'make check-abi' fails:
Running /home/jwakely/src/gcc/gcc/libstdc++-v3/testsuite/libstdc++-abi/abi.exp
...
FAIL: libstdc++-abi/abi_check
=== libstdc++ Summary ===
# of unexpected failures 1
> > Ok to commit ?
Definitely not.
