testsuite/tests/dependent/should_fail/T14066c.hs


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{-# LANGUAGE TypeFamilies, TypeInType, UndecidableInstances #-}

module T14066c where

type family H a b where
  H a b = H b a

type X = H True Nothing  -- this should fail to kind-check.
                         -- if it's accepted, then we've inferred polymorphic recursion for H