AmbiguousConstructor.agda:20,5-7
Ambiguous constructor c2.
It could refer to any of
  Foo.D.c0 (introduced at AmbiguousConstructor.agda:5,5-7)
  Foo.D.c1 (introduced at AmbiguousConstructor.agda:6,5-7)
when checking that the pattern c2 has type D
