Merge branch 'master' of http://darcs.haskell.org/ghc

3 files changed, 86 insertions, 50 deletions

diff --git a/compiler/coreSyn/CoreLint.lhs b/compiler/coreSyn/CoreLint.lhs
index cd041a5d15..cc25ece652 100644
--- a/compiler/coreSyn/CoreLint.lhs
+++ b/compiler/coreSyn/CoreLint.lhs
@@ -51,8 +51,7 @@ import PrelNames
 import Outputable
 import FastString
 import Util
-import Unify
-import InstEnv ( instanceBindFun )
+import OptCoercion ( checkAxInstCo )
 import Control.Monad
 import MonadUtils
 import Data.Maybe
@@ -413,31 +412,6 @@ kind coercions and produce the following substitution which is to be
 applied in the type variables:
   k_ag   ~~>   * -> *
 
-Note [Conflict checking with AxiomInstCo]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Consider the following type family and axiom:
-
-type family Equal (a :: k) (b :: k) :: Bool
-type instance where
-  Equal a a = True
-  Equal a b = False
---
-Equal :: forall k::BOX. k -> k -> Bool
-axEqual :: { forall k::BOX. forall a::k. Equal k a a ~ True
-           ; forall k::BOX. forall a::k. forall b::k. Equal k a b ~ False }
-
-We wish to disallow (axEqual[1] <*> <Int> <Int). (Recall that the index is 0-based,
-so this is the second branch of the axiom.) The problem is that, on the surface, it
-seems that (axEqual[1] <*> <Int> <Int>) :: (Equal * Int Int ~ False) and that all is
-OK. But, all is not OK: we want to use the first branch of the axiom in this case,
-not the second. The problem is that the parameters of the first branch can unify with
-the supplied coercions, thus meaning that the first branch should be taken. See also
-Note [Instance checking within groups] in types/FamInstEnv.lhs.
-
-However, if the right-hand side of the previous branch coincides with the right-hand
-side of the selected branch, we wish to accept the AxiomInstCo. See also Note
-[Confluence checking within groups], also in types/FamInstEnv.lhs.
-
 %************************************************************************
 %*									*
 \subsection[lintCoreArgs]{lintCoreArgs}
@@ -951,7 +925,7 @@ lintCoercion co@(AxiomInstCo con ind cos)
                                       (ktvs `zip` cos)
        ; let lhs' = Type.substTys subst_l lhs
              rhs' = Type.substTy subst_r rhs
-       ; case check_no_conflict lhs' (ind - 1) of
+       ; case checkAxInstCo co of
            Just bad_index -> bad_ax $ ptext (sLit "inconsistent with") <+> (ppr bad_index)
            Nothing -> return ()
        ; return (typeKind rhs', mkTyConApp (coAxiomTyCon con) lhs', rhs') }
@@ -959,17 +933,6 @@ lintCoercion co@(AxiomInstCo con ind cos)
     bad_ax what = addErrL (hang (ptext (sLit "Bad axiom application") <+> parens what)
                         2 (ppr co))
 
-      -- See Note [Conflict checking with AxiomInstCo]
-    check_no_conflict :: [Type] -> Int -> Maybe Int
-    check_no_conflict _ (-1) = Nothing
-    check_no_conflict lhs' j
-      | SurelyApart <- tcApartTys instanceBindFun lhs' lhsj
-      = check_no_conflict lhs' (j-1)
-      | otherwise
-      = Just j
-      where
-        (CoAxBranch { cab_lhs = lhsj }) = coAxiomNthBranch con j
-
     check_ki (subst_l, subst_r) (ktv, co)
       = do { (k, t1, t2) <- lintCoercion co
            ; let ktv_kind = Type.substTy subst_l (tyVarKind ktv)
diff --git a/compiler/types/OptCoercion.lhs b/compiler/types/OptCoercion.lhs
index b16e1aae5f..d01291610e 100644
--- a/compiler/types/OptCoercion.lhs
+++ b/compiler/types/OptCoercion.lhs
@@ -10,7 +10,7 @@
 --     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
 -- for details
 
-module OptCoercion ( optCoercion ) where 
+module OptCoercion ( optCoercion, checkAxInstCo ) where 
 
 #include "HsVersions.h"
 
@@ -28,6 +28,8 @@ import Pair
 import Maybes( allMaybes )
 import FastString
 import Util
+import Unify
+import InstEnv
 \end{code}
 
 %************************************************************************
@@ -288,21 +290,37 @@ opt_trans_rule is co1 co2
 -- Push transitivity inside axioms
 opt_trans_rule is co1 co2
 
-  -- TrPushAxR/TrPushSymAxR
+  -- TrPushSymAxR
   | Just (sym, con, ind, cos1) <- co1_is_axiom_maybe
   , Just cos2 <- matchAxiom sym con ind co2
-  = fireTransRule "TrPushAxR" co1 co2 $
-    if sym 
-    then SymCo $ AxiomInstCo con ind (opt_transList is (map mkSymCo cos2) cos1)
-    else         AxiomInstCo con ind (opt_transList is cos1 cos2)
+  , True <- sym
+  , let newAxInst = AxiomInstCo con ind (opt_transList is (map mkSymCo cos2) cos1)
+  , Nothing <- checkAxInstCo newAxInst
+  = fireTransRule "TrPushSymAxR" co1 co2 $ SymCo newAxInst
 
-  -- TrPushAxL/TrPushSymAxL
+  -- TrPushAxR
+  | Just (sym, con, ind, cos1) <- co1_is_axiom_maybe
+  , Just cos2 <- matchAxiom sym con ind co2
+  , False <- sym
+  , let newAxInst = AxiomInstCo con ind (opt_transList is cos1 cos2)
+  , Nothing <- checkAxInstCo newAxInst
+  = fireTransRule "TrPushAxR" co1 co2 newAxInst
+
+  -- TrPushSymAxL
+  | Just (sym, con, ind, cos2) <- co2_is_axiom_maybe
+  , Just cos1 <- matchAxiom (not sym) con ind co1
+  , True <- sym
+  , let newAxInst = AxiomInstCo con ind (opt_transList is cos2 (map mkSymCo cos1))
+  , Nothing <- checkAxInstCo newAxInst
+  = fireTransRule "TrPushSymAxL" co1 co2 $ SymCo newAxInst
+
+  -- TrPushAxL  
   | Just (sym, con, ind, cos2) <- co2_is_axiom_maybe
   , Just cos1 <- matchAxiom (not sym) con ind co1
-  = fireTransRule "TrPushAxL" co1 co2 $
-    if sym 
-    then SymCo $ AxiomInstCo con ind (opt_transList is cos2 (map mkSymCo cos1))
-    else         AxiomInstCo con ind (opt_transList is cos1 cos2)
+  , False <- sym
+  , let newAxInst = AxiomInstCo con ind (opt_transList is cos1 cos2)
+  , Nothing <- checkAxInstCo newAxInst
+  = fireTransRule "TrPushAxL" co1 co2 newAxInst
 
   -- TrPushAxSym/TrPushSymAx
   | Just (sym1, con1, ind1, cos1) <- co1_is_axiom_maybe
@@ -338,6 +356,54 @@ fireTransRule _rule _co1 _co2 res
   = -- pprTrace ("Trans rule fired: " ++ _rule) (vcat [ppr _co1, ppr _co2, ppr res]) $
     Just res
 
+\end{code}
+
+Note [Conflict checking with AxiomInstCo]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider the following type family and axiom:
+
+type family Equal (a :: k) (b :: k) :: Bool
+type instance where
+  Equal a a = True
+  Equal a b = False
+--
+Equal :: forall k::BOX. k -> k -> Bool
+axEqual :: { forall k::BOX. forall a::k. Equal k a a ~ True
+           ; forall k::BOX. forall a::k. forall b::k. Equal k a b ~ False }
+
+We wish to disallow (axEqual[1] <*> <Int> <Int). (Recall that the index is 0-based,
+so this is the second branch of the axiom.) The problem is that, on the surface, it
+seems that (axEqual[1] <*> <Int> <Int>) :: (Equal * Int Int ~ False) and that all is
+OK. But, all is not OK: we want to use the first branch of the axiom in this case,
+not the second. The problem is that the parameters of the first branch can unify with
+the supplied coercions, thus meaning that the first branch should be taken. See also
+Note [Instance checking within groups] in types/FamInstEnv.lhs.
+
+\begin{code}
+-- | Check to make sure that an AxInstCo is internally consistent.
+-- Returns the number of the conflicting branch, if it exists
+-- See Note [Conflict checking with AxiomInstCo]
+checkAxInstCo :: Coercion -> Maybe Int
+-- defined here to avoid dependencies in Coercion
+checkAxInstCo (AxiomInstCo ax ind cos)
+  = let branch = coAxiomNthBranch ax ind
+        tvs = coAxBranchTyVars branch
+        tys = map (pFst . coercionKind) cos 
+        subst = zipOpenTvSubst tvs tys
+        lhs' = Type.substTys subst (coAxBranchLHS branch) in
+    check_no_conflict lhs' (ind-1)
+  where
+    check_no_conflict :: [Type] -> Int -> Maybe Int
+    check_no_conflict _ (-1) = Nothing
+    check_no_conflict lhs' j
+      | SurelyApart <- tcApartTys instanceBindFun lhs' lhsj
+      = check_no_conflict lhs' (j-1)
+      | otherwise
+      = Just j
+      where
+        (CoAxBranch { cab_lhs = lhsj }) = coAxiomNthBranch ax j
+checkAxInstCo _ = Nothing
+
 -----------
 wrapSym :: Bool -> Coercion -> Coercion
 wrapSym sym co | sym       = SymCo co
diff --git a/rules/build-package-data.mk b/rules/build-package-data.mk
index bbe8652ed4..86eae14477 100644
--- a/rules/build-package-data.mk
+++ b/rules/build-package-data.mk
@@ -70,11 +70,18 @@ ifneq "$$(GMP_LIB_DIRS)" ""
 $1_$2_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="$$(GMP_LIB_DIRS)"
 endif
 
+ifeq "$$(CrossCompiling)" "YES"
+$1_$2_CONFIGURE_OPTS += --configure-option=--host=$(TARGETPLATFORM)
+# We use different platform name conventions than autoconf expects,
+# but let's hope it doesn't cause problems.
+endif
+
 ifeq "$3" "0"
 $1_$2_CONFIGURE_OPTS += $$(BOOT_PKG_CONSTRAINTS)
 endif
 
 $1_$2_CONFIGURE_OPTS += --with-gcc="$$(CC_STAGE$3)"
+$1_$2_CONFIGURE_OPTS += --with-ld="$$(LD)"
 $1_$2_CONFIGURE_OPTS += --configure-option=--with-cc="$$(CC_STAGE$3)"
 $1_$2_CONFIGURE_OPTS += --with-ar="$$(AR_STAGE$3)"
 $1_$2_CONFIGURE_OPTS += --with-ranlib="$$(RANLIB)"