Failed to solve the following constraints:
  Resolve instance argument _18 : A
  Candidates
    a : A
    overlap B.a b : A
    (stuck)
  Resolve instance argument _24 : A
  Candidates
    overlap C.a c : A
    D.a d : A
    (stuck)
  Resolve instance argument _30 : A
  Candidates
    overlap B.a b : A
    a : A
    (stuck)
Unsolved metas at the following locations:
  DisallowedOverlaps.agda:27,9-11
  DisallowedOverlaps.agda:31,9-11
  DisallowedOverlaps.agda:37,9-11
