[project @ 2000-11-16 10:32:30 by simonmar]

merge rev. 1.78.2.4 (applyTy bugfix)

diff --git a/ghc/compiler/simplCore/Simplify.lhs b/ghc/compiler/simplCore/Simplify.lhs
index e027f33..67e57c4 100644 (file)
--- a/ghc/compiler/simplCore/Simplify.lhs
+++ b/ghc/compiler/simplCore/Simplify.lhs
@@ -42,7 +42,8 @@ import CoreFVs                ( mustHaveLocalBinding, exprFreeVars )
 import CoreUnfold      ( mkOtherCon, mkUnfolding, otherCons,
                          callSiteInline
                        )
-import CoreUtils       ( cheapEqExpr, exprIsDupable, exprIsTrivial, exprIsConApp_maybe,
+import CoreUtils       ( cheapEqExpr, exprIsDupable, exprIsTrivial, 
+                         exprIsConApp_maybe, mkPiType,
                          exprType, coreAltsType, exprIsValue, idAppIsCheap,
                          exprOkForSpeculation, 
                          mkCoerce, mkSCC, mkInlineMe, mkAltExpr
@@ -1556,12 +1557,31 @@ mkDupableAlt case_bndr case_bndr' cont alt@(con, bndrs, rhs)
        `thenSmpl` \ (final_bndrs', final_args) ->
 
        -- See comment about "$j" name above
-    newId SLIT("$j") (foldr (mkFunTy . idType) rhs_ty' final_bndrs')   $ \ join_bndr ->
-
-       -- Notice that we make the lambdas into one-shot-lambdas.  The
+    newId SLIT("$j") (foldr mkPiType rhs_ty' final_bndrs')     $ \ join_bndr ->
+       -- Notice the funky mkPiType.  If the contructor has existentials
+       -- it's possible that the join point will be abstracted over
+       -- type varaibles as well as term variables.
+       --  Example:  Suppose we have
+       --      data T = forall t.  C [t]
+       --  Then faced with
+       --      case (case e of ...) of
+       --          C t xs::[t] -> rhs
+       --  We get the join point
+       --      let j :: forall t. [t] -> ...
+       --          j = /\t \xs::[t] -> rhs
+       --      in
+       --      case (case e of ...) of
+       --          C t xs::[t] -> j t xs
+
+    let 
+       -- We make the lambdas into one-shot-lambdas.  The
        -- join point is sure to be applied at most once, and doing so
        -- prevents the body of the join point being floated out by
        -- the full laziness pass
-    returnSmpl ([NonRec join_bndr (mkLams (map setOneShotLambda final_bndrs') rhs')],
+       really_final_bndrs = map one_shot final_bndrs'
+       one_shot v | isId v    = setOneShotLambda v
+                  | otherwise = v
+    in
+    returnSmpl ([NonRec join_bndr (mkLams really_final_bndrs rhs')],
                (con, bndrs, mkApps (Var join_bndr) final_args))
 \end{code}