Add compiler/testdata/go1.27.go, gated behind Go >= 1.27 (the version
that promoted generic methods out of the GenericMethods experiment),
covering both fixes from the previous two commits:
- genericMethod has a regular method and a generic method (its own
type parameter); boxing it into an interface must only include the
regular method in the runtime method set instead of panicking in
getTypeCodeName.
- onlyGenericMethod's sole method is generic, so its type code must
have hasMethodSet == false and no methodSet field at all, not an
empty one.
Verified this test panics on the pre-fix compiler/interface.go and
passes after it.
Damian Gryski
2a49216152