Walter and I discussed what auto ref for templates should look like and reached the conclusion that an approach based on lowering would be best. I added a proposed lowering to https://github.com/D-Programming-Language/dmd/pull/4717.
`For example, consider the declaration:`
ref int fun(auto ref int x);
`That should lower to:`
ref int fun(int' x); /* or */ ref int fun('int x);
