Fix GADT refinement fix-pointing, add ASSERTs and a WARN, make type equality function...

Mon Sep 18 17:07:38 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
  * Fix GADT refinement fix-pointing, add ASSERTs and a WARN, make type equality functions work for PredTy Eqtype ...
  Sun Aug  6 20:28:50 EDT 2006  Manuel M T Chakravarty <chak@cse.unsw.edu.au>
    * Fix GADT refinement fix-pointing, add ASSERTs and a WARN, make type equality functions work for PredTy Eqtype ...
    Tue Aug  1 06:14:43 EDT 2006  kevind@bu.edu

diff --git a/compiler/typecheck/TcGadt.lhs b/compiler/typecheck/TcGadt.lhs
index deac1eb..6c63593 100644 (file)
--- a/compiler/typecheck/TcGadt.lhs
+++ b/compiler/typecheck/TcGadt.lhs
@@ -18,14 +18,14 @@ module TcGadt (
 
 import HsSyn   ( ExprCoFn(..), idCoercion, isIdCoercion )
 import Coercion        ( Coercion, mkSymCoercion, mkTransCoercion, mkUnsafeCoercion,
-                 mkLeftCoercion, mkRightCoercion,
+                 mkLeftCoercion, mkRightCoercion, mkCoKind, coercionKindPredTy,
                  splitCoercionKind, decomposeCo )
 import TcType  ( TvSubst(..), TvSubstEnv, substTy, mkTvSubst, 
                  substTyVar, zipTopTvSubst, typeKind,
                  eqKind, isSubKind, repSplitAppTy_maybe,
                  tcView
                )
-import Type    ( Type, tyVarsOfType, tyVarsOfTypes )
+import Type    ( Type, tyVarsOfType, tyVarsOfTypes, tcEqType, mkTyVarTy )
 import TypeRep ( Type(..), PredType(..) )
 import DataCon ( DataCon, dataConUnivTyVars, dataConEqSpec )
 import Var     ( CoVar, TyVar, tyVarKind )
@@ -201,14 +201,16 @@ fixTvCoEnv in_scope env
   where
     fixpt         = mapVarEnv step env
 
-    step (co, ty) = (co', ty')
+    step (co, ty) = (co1, ty')
       -- Apply fixpt one step:
       -- Use refineType to get a substituted type, ty', and a coercion, co_fn,
       -- which justifies the substitution.  If the coercion is not the identity
       -- then use transitivity with the original coercion
       where
         (co_fn, ty') = refineType (Reft in_scope fixpt) ty
-        co' | ExprCoFn co'' <- co_fn = mkTransCoercion co co''
+        co1 | ExprCoFn co'' <- co_fn = mkTransCoercion co'' co
+                                         -- This trans looks backwards, but it
+                                         -- works somehow
             | otherwise              = ASSERT( isIdCoercion co_fn ) co 
 
 -----------------------------
@@ -237,6 +239,8 @@ dataConCanMatch con tys
 tryToBind :: TyVarSet -> TyVar -> BindFlag
 tryToBind tv_set tv | tv `elemVarSet` tv_set = BindMe
                    | otherwise              = AvoidMe
+
+
 \end{code}
 
 
@@ -409,9 +413,12 @@ uUnrefined subst co tv1 ty2 (TyVarTy tv2)
     ty1 = TyVarTy tv1
     k1 = tyVarKind tv1
     k2 = tyVarKind tv2
-    bind swap tv ty = return (extendVarEnv subst tv (co',ty))
+    bind swap tv ty = 
+        ASSERT2( (coercionKindPredTy co1 `tcEqType` mkCoKind (mkTyVarTy tv) ty)
+               , (text "Refinement invariant failure: co = " <+> ppr co  <+> ppr (coercionKindPredTy co) $$ text "subst = " <+> ppr tv <+> ppr (mkCoKind (mkTyVarTy tv) ty)))
+        return (extendVarEnv subst tv (co1,ty))
       where
-        co' = if swap then mkSymCoercion co else co
+        co1 = if swap then mkSymCoercion co else co
 
 uUnrefined subst co tv1 ty2 ty2'       -- ty2 is not a type variable
   | tv1 `elemVarSet` substTvSet subst (tyVarsOfType ty2')
@@ -435,7 +442,9 @@ substTvSet subst tvs
                Just (_,ty) -> substTvSet subst (tyVarsOfType ty)
 
 bindTv subst co tv ty  -- ty is not a type variable
-  = do { b <- tvBindFlag tv
+  = ASSERT2( (coercionKindPredTy co `tcEqType` mkCoKind (mkTyVarTy tv) ty), 
+          (text "Refinement invariant failure: co = " <+> ppr co  <+> ppr (coercionKindPredTy co) $$ text "subst = " <+> ppr tv <+> ppr (mkCoKind (mkTyVarTy tv) ty))  )
+    do  { b <- tvBindFlag tv
        ; case b of
            Skolem   -> failWith (misMatch (TyVarTy tv) ty)
            WildCard -> return subst

diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs
index 54061ed..c9de505 100644 (file)
--- a/compiler/types/Coercion.lhs
+++ b/compiler/types/Coercion.lhs
@@ -36,7 +36,8 @@ module Coercion (
 import TypeRep
 import Type      ( Type, Kind, PredType, substTyWith, mkAppTy, mkForAllTy,
                     mkFunTy, splitAppTy_maybe, splitForAllTy_maybe, coreView,
-                    kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys
+                    kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys,
+                    coreEqType
                   )
 import TyCon      ( TyCon, tyConArity, mkCoercionTyCon, isNewTyCon,
                     newTyConRhs, newTyConCo, 
@@ -309,7 +310,9 @@ symCoercionTyCon =
 transCoercionTyCon = 
   mkCoercionTyCon transCoercionTyConName 2 (mkKindingFun composeCoercionKindsOf)
   where
-    composeCoercionKindsOf (co1:co2:rest) = (a1, r2, rest)
+    composeCoercionKindsOf (co1:co2:rest) = 
+        WARN( not (r1 `coreEqType` a2), text "Strange! Type mismatch in trans coercion, probably a bug")
+        (a1, r2, rest)
       where
         (a1, r1) = coercionKind co1
         (a2, r2) = coercionKind co2 

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index 5799147..2aa31eb 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -1029,6 +1029,7 @@ cmpPredX env (IParam n1 ty1) (IParam n2 ty2) = (n1 `compare` n2) `thenCmp` cmpTy
 cmpPredX env (ClassP c1 tys1) (ClassP c2 tys2) = (c1 `compare` c2) `thenCmp` cmpTypesX env tys1 tys2
 cmpPredX env (IParam _ _)     (ClassP _ _)     = LT
 cmpPredX env (ClassP _ _)     (IParam _ _)     = GT
+cmpPredX env (EqPred ty1 ty2) (EqPred ty1' ty2') = (cmpTypeX env ty1 ty1') `thenCmp` (cmpTypeX env ty2 ty2')
 \end{code}
 
 PredTypes are used as a FM key in TcSimplify,