testsuite/tests/typecheck/should_fail/tcfail223.hs

   1 {-# LANGUAGE FlexibleInstances, UndecidableInstances #-}
   2 module ShouldFail where
   3
   4 class Class1 a
   5 class Class1 a => Class2 a
   6 class Class2 a => Class3 a
   7
   8 -- This was wrongfully accepted by ghc-7.0 to ghc-7.10.
   9 -- It is missing a `Class1 a` constraint.
  10 instance Class3 a => Class2 a