Issue 4070 was rejected on the grounds of symmetry. My sense is that Walter’s objections are invalid. There is precedent for asymmetry on function declarations:
`ref` prefix-only.

Worse, `ref const int f() { }` really, really looks like `const` applies to the return type.

If breakage is deemed too much, this can be done in the next edition of D (assuming editions are being implemented). All prefix type constructors should be applied to the return type. Everything that affects the function (or function type) or the implicit this goes at the end as a (member) function attribute.