From: Ian Lynagh <igloo@earth.li>
Date: Tue, 10 Jul 2007 12:47:38 +0000 (+0000)
Subject: Fix tcInstHeadTyNotSynonym
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=11e80952ae15cf95b89c01466ee1970fb7161d7f

Fix tcInstHeadTyNotSynonym
It was returning False for type variables amongst other things, so
"instance C a" was telling us to use -XTypeSynonymInstances.
---

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 7595a75..eaf2faa 100644
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -797,10 +797,9 @@ tcInstHeadTyNotSynonym :: Type -> Bool
 -- are transparent, so we need a special function here
 tcInstHeadTyNotSynonym ty
   = case ty of
-	NoteTy _ ty     -> tcInstHeadTyNotSynonym ty
-	TyConApp tc tys -> not (isSynTyCon tc)
-	FunTy arg res   -> True
-	other		-> False
+        NoteTy _ ty     -> tcInstHeadTyNotSynonym ty
+        TyConApp tc tys -> not (isSynTyCon tc)
+        _ -> True
 
 tcInstHeadTyAppAllTyVars :: Type -> Bool
 -- Used in Haskell-98 mode, for the argument types of an instance head