[Bug libstdc++/86015] Better handling of iterator distances

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86015

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-05-31
          Component|c++                         |libstdc++
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think all those _Distance types comes from
iterator_traits<Iter>::difference_type, and by my reading of the standard an
iterator's difference type is required to be a signed integer type.

But it seems harmless to make the suggested change, it won't affect any valid
code.