[project @ 2005-01-06 00:28:05 by simonpj]

Wibble; fixes tcTyVarDetails breakage

diff --git a/ghc/compiler/types/InstEnv.lhs b/ghc/compiler/types/InstEnv.lhs
index 46ab2cb..965ba55 100644 (file)
--- a/ghc/compiler/types/InstEnv.lhs
+++ b/ghc/compiler/types/InstEnv.lhs
@@ -17,7 +17,7 @@ module InstEnv (
 #include "HsVersions.h"
 
 import Class           ( Class, classTvsFds )
-import Var             ( Id )
+import Var             ( Id, isTcTyVar )
 import VarSet
 import Type            ( TvSubst )
 import TcType          ( Type, tcTyConAppTyCon, tcIsTyVarTy,
@@ -332,8 +332,8 @@ lookup_inst_env env key_cls key_tys key_all_tvs
                Just _   -> find rest ms (dfun_id:us)
                Nothing  -> find rest ms us
 
-    bind_fn tv | isExistentialTyVar tv = Skolem
-              | otherwise             = BindMe
+    bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem
+              | otherwise                             = BindMe
        -- The key_tys can contain skolem constants, and we can guarantee that those
        -- are never going to be instantiated to anything, so we should not involve
        -- them in the unification test.  Example: