Straightened out implicit coercions for indexed types

[ghc-hetmet.git] / compiler / iface / TcIface.lhs

diff --git a/compiler/iface/TcIface.lhs b/compiler/iface/TcIface.lhs
index 2831c2d..68abd23 100644 (file)
--- a/compiler/iface/TcIface.lhs
+++ b/compiler/iface/TcIface.lhs
@@ -31,7 +31,7 @@ import Type           ( liftedTypeKind, splitTyConApp, mkTyConApp,
                          mkTyVarTys, ThetaType )
 import TypeRep         ( Type(..), PredType(..) )
 import TyCon           ( TyCon, tyConName, SynTyConRhs(..), 
-                         AlgTyConParent(..) )
+                         AlgTyConParent(..), setTyConArgPoss )
 import HscTypes                ( ExternalPackageState(..), 
                          TyThing(..), tyThingClass, tyThingTyCon, 
                          ModIface(..), ModDetails(..), HomeModInfo(..),
@@ -69,6 +69,8 @@ import SrcLoc         ( noSrcLoc )
 import Util            ( zipWithEqual, equalLength, splitAtList )
 import DynFlags                ( DynFlag(..), isOneShot )
 
+import List            ( elemIndex)
+import Maybe           ( catMaybes )
 import Monad           ( liftM )
 \end{code}
 
@@ -369,11 +371,11 @@ tcIfaceDecl (IfaceData {ifName = occ_name,
            { stupid_theta <- tcIfaceCtxt ctxt
            ; famInst <- 
                case mb_family of
-                 Nothing         -> return Nothing
-                 Just (fam, tys) -> 
+                 Nothing                -> return Nothing
+                 Just (fam, tys, index) -> 
                    do { famTyCon <- tcIfaceTyCon fam
                       ; insttys <- mapM tcIfaceType tys
-                      ; return $ Just (famTyCon, insttys)
+                      ; return $ Just (famTyCon, insttys, index)
                       }
            ; cons <- tcIfaceDataCons tc_name tycon tyvars rdr_cons
            ; buildAlgTyCon tc_name tyvars stupid_theta
@@ -393,8 +395,9 @@ tcIfaceDecl (IfaceSyn {ifName = occ_name, ifTyVars = tv_bndrs,
      ; return (ATyCon (buildSynTyCon tc_name tyvars rhs))
      }
 
-tcIfaceDecl (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, ifTyVars = tv_bndrs, 
-                        ifFDs = rdr_fds, ifSigs = rdr_sigs, 
+tcIfaceDecl (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, 
+                        ifTyVars = tv_bndrs, ifFDs = rdr_fds, 
+                        ifATs = rdr_ats, ifSigs = rdr_sigs, 
                         ifRec = tc_isrec })
 -- ToDo: in hs-boot files we should really treat abstract classes specially,
 --      as we do abstract tycons
@@ -403,7 +406,9 @@ tcIfaceDecl (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, ifTyVars = tv_bnd
     ; ctxt <- tcIfaceCtxt rdr_ctxt
     ; sigs <- mappM tc_sig rdr_sigs
     ; fds  <- mappM tc_fd rdr_fds
-    ; cls  <- buildClass cls_name tyvars ctxt fds sigs tc_isrec
+    ; ats'  <- mappM tcIfaceDecl rdr_ats
+    ; let ats = zipWith setTyThingPoss ats' (map ifTyVars rdr_ats)
+    ; cls  <- buildClass cls_name tyvars ctxt fds ats sigs tc_isrec
     ; return (AClass cls) }
   where
    tc_sig (IfaceClassOp occ dm rdr_ty)
@@ -420,6 +425,19 @@ tcIfaceDecl (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, ifTyVars = tv_bnd
                           ; tvs2' <- mappM tcIfaceTyVar tvs2
                           ; return (tvs1', tvs2') }
 
+   -- For each AT argument compute the position of the corresponding class
+   -- parameter in the class head.  This will later serve as a permutation
+   -- vector when checking the validity of instance declarations.
+   setTyThingPoss (ATyCon tycon) atTyVars = 
+     let classTyVars = map fst tv_bndrs
+        poss        =   catMaybes 
+                      . map ((`elemIndex` classTyVars) . fst) 
+                      $ atTyVars
+                   -- There will be no Nothing, as we already passed renaming
+     in 
+     ATyCon (setTyConArgPoss tycon poss)
+   setTyThingPoss _              _ = panic "TcIface.setTyThingPoss"
+
 tcIfaceDecl (IfaceForeign {ifName = rdr_name, ifExtName = ext_name})
   = do { name <- lookupIfaceTop rdr_name
        ; return (ATyCon (mkForeignTyCon name ext_name