Test Trac #9565 and #9583

testsuite/tests/simplCore/should_compile/T9565.hs

+{-# LANGUAGE TypeFamilies, FlexibleContexts, UndecidableInstances #-}
+
+-- This is a copy of typecheck/should_run/T3500b, but it's here for
+-- a different reason: at one time, it sent the compiler into a loop.
+-- ANd T3500b isn't tested 'fast' mode
+
+module T9565 where
+
+newtype Mu f = Mu (f (Mu f))
+
+type family Id m
+type instance Id m = m
+
+instance Show (Id (f (Mu f))) => Show (Mu f) where
+    show (Mu f) = show f
+
+showMu :: Mu (Either ()) -> String
+showMu = show
+
+item :: Mu (Either ())
+item = Mu (Right (Mu (Left ())))
+
+main = print (showMu item)

testsuite/tests/simplCore/should_compile/T9583.hs

+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# OPTIONS_GHC -O #-}
+
+module T9583 where
+
+import Data.Binary      ( Binary(..) )
+import Data.Data        ( Data )
+import Data.Typeable    ( Typeable )  
+import GHC.Generics     ( Generic )
+
+data T = A
+       | B
+       | C T
+       | D T T
+       | E T T
+  deriving (Data, Generic, Typeable)
+
+instance Binary T

testsuite/tests/simplCore/should_compile/all.T

@@ -207,3 +207,5 @@ test('T8848a', only_ways(['optasm']), compile, ['-ddump-rules'])
 test('T8331', only_ways(['optasm']), compile, ['-ddump-rules'])
 test('T6056', only_ways(['optasm']), multimod_compile, ['T6056', '-v0 -ddump-rule-firings'])
 test('T9400', only_ways(['optasm']), compile, ['-O0 -ddump-simpl -dsuppress-uniques'])
+test('T9583', only_ways(['optasm']), compile, [''])
+test('T9565', only_ways(['optasm']), compile, [''])