∀ (lhs rhs : String) (lstart rstart len : String.Pos.Raw) (h1 : len.offsetBy lstart ≤ lhs.rawEndPos)
  (h2 : len.offsetBy rstart ≤ rhs.rawEndPos),
  String.Slice.Pattern.Internal.memcmpStr lhs rhs lstart rstart len h1 h2 =
    String.Slice.Pattern.Internal.memcmpStr.go✝ lhs rhs lstart rstart len h1 h2 0