_GLIBCXX_DEBUG detects issues in flat_set/map

[Jean-Michaël Celerier]

In boost 1.81, g++ 12.2

Repro:

#include <boost/container/flat_set.hpp>
#include <string>
#include <vector>

boost::container::flat_set<std::string, std::less<>, std::vector<std::string>>
    widgetFuncMap{{"floatslider"}, {"logfloatslider"}, {"intslider"},
                  {"intspinbox"},  {"toggle"},         {"lineedit"},
                  {"combobox"},    {"button"},         {"hsvslider"},
                  {"xyslider"},    {"multislider"}};

int main() {}

$ g++  -D_GLIBCXX_DEBUG bug.cpp
$ ./a.out
/usr/include/c++/12.2.1/debug/safe_iterator.h:318:
In function:
    gnu_debug::_Safe_iterator<_Iterator, _Sequence, _Category>::pointer 
    gnu_debug::_Safe_iterator<_Iterator, _Sequence, _Category>::operator->() 
    const [with _Iterator = gnu_cxx::normal_iterator<std::
    cxx11::basic_string<char>*, std::vector<std::cxx11::basic_string<char>, 
    std::allocator<std::cxx11::basic_string<char> > > >; _Sequence = std::
    debug::vector<std::cxx11::basic_string<char> >; _Category = 
    std::forward_iterator_tag; pointer = std::cxx11::basic_string<char>*]

Error: attempt to dereference a past-the-end iterator.

Objects involved in the operation:
    iterator "this" @ 0x7ffc1a98e5e0 {
      type = gnu_cxx::normal_iterator<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::vector<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > (mutable iterator);
      state = past-the-end;
      references sequence with type 'std::debug::vector<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >' @ 0x55704a2f5180
    }
[1]    23018 IOT instruction (core dumped)  ./a.out

[Ion Gaztañaga]

Many thanks for the report. iterator_to_raw_pointer interferes with checked iterators, this is a issue that libstdc++ also has solved:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93960