[Bug c++/100465] Overloading operator+= and including filesystem causes conflicting overload compilation error

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100465

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-05-07
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The difference is this change from g:e7406c364496dae51ef294b5720923fe4a1dfccb

@@ -1082,7 +1085,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
 #endif
              if (__add_slash)
                __str += __slash;
-             __str += __elem._M_pathname;
+             __str += basic_string_view<value_type>(__elem._M_pathname);
              __add_slash = __elem._M_type() == _Type::_Filename;
            }
        }

Previously it was adding a std::string to a basic_string<char,
char_traits<char>, Alloc>, which only worked if the Alloc was
std::allocator<char>.

The change to use string_view is required, but results in this error. I'll try
to reduce the testcase.