[Bug libstdc++/80034] New: [5/6 Regression] unqualified calls to std::distance in std::list::sort

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80034

            Bug ID: 80034
           Summary: [5/6 Regression] unqualified calls to std::distance in
                    std::list::sort
           Product: gcc
           Version: 6.3.1
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
                CC: ville at gcc dot gnu.org
  Target Milestone: ---

This no longer compiles on the gcc-5 or gcc-6 branches:

#include <list>

namespace X {
  struct Y { };
  bool operator<(Y, Y) { return false; }
  template<typename T>
    void distance(T, T) { }
}

int main()
{
  std::list<X::Y> l;
  l.sort();
}

Caused by r244475 and r244474