From d5f79e6e7bab767de9c528ac343132d8daeab0da Mon Sep 17 00:00:00 2001
From: simonpj <unknown>
Date: Mon, 5 Nov 2001 16:45:02 +0000
Subject: [PATCH] [project @ 2001-11-05 16:45:02 by simonpj] Wibble to eta
 reduction

---
 ghc/compiler/simplCore/SimplUtils.lhs |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/ghc/compiler/simplCore/SimplUtils.lhs b/ghc/compiler/simplCore/SimplUtils.lhs
index ffeb43c..51504c6 100644
--- a/ghc/compiler/simplCore/SimplUtils.lhs
+++ b/ghc/compiler/simplCore/SimplUtils.lhs
@@ -546,7 +546,11 @@ tryEtaReduce bndrs body
     go []       (Var fun)     | ok_fun fun   = Just (Var fun)	-- Success!
     go _        _			     = Nothing		-- Failure!
 
-    ok_fun fun   = not (fun `elem` bndrs)
+    ok_fun fun   = not (fun `elem` bndrs) && 
+		   isEvaldUnfolding (idUnfolding fun)
+	-- The exprIsValue is because eta reduction is not 
+	-- valid in general:  \x. bot  /=  bot
+	-- So we need to be sure that the "fun" is a value.
     ok_arg b arg = varToCoreExpr b `cheapEqExpr` arg
 \end{code}
 
-- 
1.7.10.4