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diff --git a/testsuite/tests/codeGen/should_run/cgrun050.hs b/testsuite/tests/codeGen/should_run/cgrun050.hs
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+++ b/testsuite/tests/codeGen/should_run/cgrun050.hs
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+-- !! Test strict, recursive newtypes
+-- This test made a pre-5.02 fall over
+-- Reason: the seq arising from the !F didn't see that
+-- the represtation of F is a function. 
+
+-- NB It's crucial to compile this test *without* -O
+-- The $ then prevents the 'F' from seeing the '\x'
+-- and hence makes the evaluation happen at runtime
+
+module Main ( main ) where
+
+newtype F = F (Int -> Val)	-- NB: F and Val are
+data Val = VFn !F |  VInt !Int	-- mutually recursive
+
+f :: Val -> Val
+f (VFn (F f)) = f 4
+
+main = print (f (VFn (F $ (\x -> VInt (x+3)))))
+
+instance Show Val where
+  show (VInt n) = show n
+
+