[Bug c++/77733] New: Add fixit hint suggesting to use std::move

["redi at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77733

            Bug ID: 77733
           Summary: Add fixit hint suggesting to use std::move
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

struct X { };

struct Y {
  void foo();
  void foo(X&&);
  void foo(int, const X&);
  void foo(int, X&&);
};

int main()
{
  X x;
  Y y;
  y.foo(x);
}

Produces the error:

move.cc: In function ‘int main()’:
move.cc:14:10: error: cannot bind rvalue reference of type ‘X&&’ to lvalue of
type ‘X’
   y.foo(x);
          ^
move.cc:5:8: note:   initializing argument 1 of ‘void Y::foo(X&&)’
   void foo(X&&);
        ^~~

It would be useful to suggest using std::move(x) instead.