X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcType.lhs;h=50ac35ab50a97d0a65ac6d795704440ec82d7638;hp=89aba6504f1d4fce2f54642c76026afb540a7519;hb=4d8c7c976104d2e39a1183967ec0f254a0fc0a47;hpb=492303f32eb179c14a095aa175541bdbff486179

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 89aba65..50ac35a 100644
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -956,6 +956,9 @@ tcInstHeadTyAppAllTyVars :: Type -> Bool
 -- Used in Haskell-98 mode, for the argument types of an instance head
 -- These must be a constructor applied to type variable arguments
 tcInstHeadTyAppAllTyVars ty
+  | Just ty' <- tcView ty       -- Look through synonyms
+  = tcInstHeadTyAppAllTyVars ty'
+  | otherwise
   = case ty of
 	TyConApp _ tys  -> ok tys
 	FunTy arg res   -> ok [arg, res]