Fix Trac #2018: float-out was ignoring the kind of a coercion variable

[ghc-hetmet.git] / compiler / simplCore / SetLevels.lhs

diff --git a/compiler/simplCore/SetLevels.lhs b/compiler/simplCore/SetLevels.lhs
index 043b036..705d545 100644 (file)
--- a/compiler/simplCore/SetLevels.lhs
+++ b/compiler/simplCore/SetLevels.lhs
@@ -72,7 +72,7 @@ import Id             ( Id, idType, mkSysLocal, isOneShotLambda,
                          idSpecialisation, idWorkerInfo, setIdInfo
                        )
 import IdInfo          ( workerExists, vanillaIdInfo, isEmptySpecInfo )
-import Var             ( Var )
+import Var
 import VarSet
 import VarEnv
 import Name            ( getOccName )
@@ -772,38 +772,41 @@ abstractVars :: Level -> LevelEnv -> VarSet -> [Var]
        -- Find the variables in fvs, free vars of the target expresion,
        -- whose level is greater than the destination level
        -- These are the ones we are going to abstract out
-abstractVars dest_lvl env fvs
-  = uniq (sortLe le [var | fv <- varSetElems fvs, var <- absVarsOf dest_lvl env fv])
+abstractVars dest_lvl (_, lvl_env, _, id_env) fvs
+  = uniq (sortLe le [var | fv <- varSetElems fvs
+                        , var <- absVarsOf id_env fv
+                        , abstract_me var])
   where
-       -- Sort the variables so we don't get 
-       -- mixed-up tyvars and Ids; it's just messy
-    v1 `le` v2 = case (isId v1, isId v2) of
-                  (True, False) -> False
-                  (False, True) -> True
+       -- Sort the variables so the true type variables come first;
+       -- the tyvars scope over Ids and coercion vars
+    v1 `le` v2 = case (is_tv v1, is_tv v2) of
+                  (True, False) -> True
+                  (False, True) -> False
                   other         -> v1 <= v2    -- Same family
 
+    is_tv v = isTyVar v && not (isCoVar v)
+
     uniq :: [Var] -> [Var]
        -- Remove adjacent duplicates; the sort will have brought them together
     uniq (v1:v2:vs) | v1 == v2  = uniq (v2:vs)
                    | otherwise = v1 : uniq (v2:vs)
     uniq vs = vs
 
-absVarsOf :: Level -> LevelEnv -> Var -> [Var]
+    abstract_me v = case lookupVarEnv lvl_env v of
+                       Just lvl -> dest_lvl `ltLvl` lvl
+                       Nothing  -> False
+
+absVarsOf :: IdEnv ([Var], LevelledExpr) -> Var -> [Var]
        -- If f is free in the expression, and f maps to poly_f a b c in the
        -- current substitution, then we must report a b c as candidate type
        -- variables
-absVarsOf dest_lvl (_, lvl_env, _, id_env) v 
-  | isId v
-  = [zap av2 | av1 <- lookup_avs v, av2 <- add_tyvars av1, abstract_me av2]
-
-  | otherwise
-  = if abstract_me v then [v] else []
+absVarsOf id_env v 
+  | isId v    = [zap av2 | av1 <- lookup_avs v
+                        , av2 <- add_tyvars av1]
+  | isCoVar v = add_tyvars v
+  | otherwise = [v]
 
   where
-    abstract_me v = case lookupVarEnv lvl_env v of
-                       Just lvl -> dest_lvl `ltLvl` lvl
-                       Nothing  -> False
-
     lookup_avs v = case lookupVarEnv id_env v of
                        Just (abs_vars, _) -> abs_vars
                        Nothing            -> [v]