X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FhsSyn%2FHsUtils.lhs;h=3b9271a633d4996d5fc7a3f54fca43cb38c5aa96;hp=9bd34482adcb60c285e3ea4684da87f4dd97c592;hb=7fc749a43b4b6b85d234fa95d4928648259584f4;hpb=90dc9026b091be5cca5da4c6cbd3713ecc493361

diff --git a/compiler/hsSyn/HsUtils.lhs b/compiler/hsSyn/HsUtils.lhs
index 9bd3448..3b9271a 100644
--- a/compiler/hsSyn/HsUtils.lhs
+++ b/compiler/hsSyn/HsUtils.lhs
@@ -13,6 +13,13 @@ which deal with the intantiated versions are located elsewhere:
    Id			typecheck/TcHsSyn	
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module HsUtils where
 
 #include "HsVersions.h"
@@ -22,7 +29,6 @@ import HsExpr
 import HsPat
 import HsTypes	
 import HsLit
-import HsDecls
 
 import RdrName
 import Var
@@ -101,7 +107,7 @@ mkHsDictLet binds expr
 			    val_binds = ValBindsOut [(Recursive, binds)] []
 
 mkHsConApp :: DataCon -> [Type] -> [HsExpr Id] -> LHsExpr Id
--- Used for constructing dictinoary terms etc, so no locations 
+-- Used for constructing dictionary terms etc, so no locations 
 mkHsConApp data_con tys args 
   = foldl mk_app (nlHsTyApp (dataConWrapId data_con) tys) args
   where
@@ -320,22 +326,24 @@ collectHsBindLocatedBinders binds = foldrBag (collectAcc . unLoc) [] binds
 %************************************************************************
 
 \begin{code}
-collectLStmtsBinders :: [LStmt id] -> [Located id]
+collectLStmtsBinders :: OutputableBndr id => [LStmt id] -> [Located id]
 collectLStmtsBinders = concatMap collectLStmtBinders
 
-collectStmtsBinders :: [Stmt id] -> [Located id]
+collectStmtsBinders :: OutputableBndr id => [Stmt id] -> [Located id]
 collectStmtsBinders = concatMap collectStmtBinders
 
-collectLStmtBinders :: LStmt id -> [Located id]
+collectLStmtBinders :: OutputableBndr id => LStmt id -> [Located id]
 collectLStmtBinders = collectStmtBinders . unLoc
 
-collectStmtBinders :: Stmt id -> [Located id]
+collectStmtBinders :: OutputableBndr id => Stmt id -> [Located id]
   -- Id Binders for a Stmt... [but what about pattern-sig type vars]?
 collectStmtBinders (BindStmt pat _ _ _) = collectLocatedPatBinders pat
 collectStmtBinders (LetStmt binds)      = collectLocalBinders binds
-collectStmtBinders (ExprStmt _ _ _)   	= []
-collectStmtBinders (RecStmt ss _ _ _ _)	= collectLStmtsBinders ss
-collectStmtBinders other              	= panic "collectStmtBinders"
+collectStmtBinders (ExprStmt _ _ _)     = []
+collectStmtBinders (ParStmt xs)         = collectLStmtsBinders
+                                        $ concatMap fst xs
+collectStmtBinders (RecStmt ss _ _ _ _) = collectLStmtsBinders ss
+collectStmtBinders s                    = pprPanic "collectStmtBinders" (ppr s)
 \end{code}
 
 
@@ -382,8 +390,8 @@ collectl (L l pat) bndrs
     go (PArrPat pats _)    	  = foldr collectl bndrs pats
     go (TuplePat pats _ _)  	  = foldr collectl bndrs pats
 				  
-    go (ConPatIn c ps)   	  = foldr collectl bndrs (hsConArgs ps)
-    go (ConPatOut {pat_args=ps})  = foldr collectl bndrs (hsConArgs ps)
+    go (ConPatIn c ps)   	  = foldr collectl bndrs (hsConPatArgs ps)
+    go (ConPatOut {pat_args=ps})  = foldr collectl bndrs (hsConPatArgs ps)
 	-- See Note [Dictionary binders in ConPatOut]
     go (LitPat _)	      	  = bndrs
     go (NPat _ _ _ _)		  = bndrs
@@ -392,8 +400,6 @@ collectl (L l pat) bndrs
     go (SigPatIn pat _)	 	  = collectl pat bndrs
     go (SigPatOut pat _)	  = collectl pat bndrs
     go (TypePat ty)               = bndrs
-    go (DictPat ids1 ids2)        = map noLoc ids1 ++ map noLoc ids2
-				    ++ bndrs
     go (CoPat _ pat ty)           = collectl (noLoc pat) bndrs
 \end{code}
 
@@ -407,6 +413,22 @@ collectPatBinders.  In a lazy pattern, for example f ~(C x y) = ...,
 we want to generate bindings for x,y but not for dictionaries bound by
 C.  (The type checker ensures they would not be used.)
 
+Desugaring of arrow case expressions needs these bindings (see DsArrows
+and arrowcase1), but SPJ (Jan 2007) says it's safer for it to use its
+own pat-binder-collector:
+
+Here's the problem.  Consider
+
+data T a where
+   C :: Num a => a -> Int -> T a
+
+f ~(C (n+1) m) = (n,m)
+
+Here, the pattern (C (n+1)) binds a hidden dictionary (d::Num a),
+and *also* uses that dictionary to match the (n+1) pattern.  Yet, the
+variables bound by the lazy pattern are n,m, *not* the dictionary d.
+So in mkSelectorBinds in DsUtils, we want just m,n as the variables bound.
+
 \begin{code}
 collectSigTysFromPats :: [InPat name] -> [LHsType name]
 collectSigTysFromPats pats = foldr collect_lpat [] pats
@@ -426,6 +448,6 @@ collect_pat (ParPat  pat)      	acc = collect_lpat pat acc
 collect_pat (ListPat pats _)   	acc = foldr collect_lpat acc pats
 collect_pat (PArrPat pats _)   	acc = foldr collect_lpat acc pats
 collect_pat (TuplePat pats _ _) acc = foldr collect_lpat acc pats
-collect_pat (ConPatIn c ps)     acc = foldr collect_lpat acc (hsConArgs ps)
+collect_pat (ConPatIn c ps)     acc = foldr collect_lpat acc (hsConPatArgs ps)
 collect_pat other	        acc = acc 	-- Literals, vars, wildcard
 \end{code}