Fix Trac #2412: type synonyms and hs-boot recursion

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

diff --git a/compiler/iface/TcIface.lhs b/compiler/iface/TcIface.lhs
index 2dcdf78..32735a4 100644 (file)
--- a/compiler/iface/TcIface.lhs
+++ b/compiler/iface/TcIface.lhs
@@ -68,7 +68,7 @@ This module takes
 An IfaceDecl is populated with RdrNames, and these are not renamed to
 Names before typechecking, because there should be no scope errors etc.
 
 An IfaceDecl is populated with RdrNames, and these are not renamed to
 Names before typechecking, because there should be no scope errors etc.
 

-       -- For (b) consider: f = $(...h....)
+       -- For (b) consider: f = \$(...h....)

        -- where h is imported, and calls f via an hi-boot file.  
        -- This is bad!  But it is not seen as a staging error, because h
        -- is indeed imported.  We don't want the type-checker to black-hole 
        -- where h is imported, and calls f via an hi-boot file.  
        -- This is bad!  But it is not seen as a staging error, because h
        -- is indeed imported.  We don't want the type-checker to black-hole 

@@ -356,14 +356,13 @@ tcIfaceDecl ignore_prags (IfaceId {ifName = occ_name, ifType = iface_type, ifIdI
        ; info <- tcIdInfo ignore_prags name ty info
        ; return (AnId (mkVanillaGlobalWithInfo name ty info)) }
 
        ; info <- tcIdInfo ignore_prags name ty info
        ; return (AnId (mkVanillaGlobalWithInfo name ty info)) }
 

-tcIfaceDecl _
-           (IfaceData {ifName = occ_name, 
-                       ifTyVars = tv_bndrs, 
-                       ifCtxt = ctxt, ifGadtSyntax = gadt_syn,
-                       ifCons = rdr_cons, 
-                       ifRec = is_rec, 
-                       ifGeneric = want_generic,
-                       ifFamInst = mb_family })
+tcIfaceDecl _ (IfaceData {ifName = occ_name, 
+                         ifTyVars = tv_bndrs, 
+                         ifCtxt = ctxt, ifGadtSyntax = gadt_syn,
+                         ifCons = rdr_cons, 
+                         ifRec = is_rec, 
+                         ifGeneric = want_generic,
+                         ifFamInst = mb_family })

   = do { tc_name <- lookupIfaceTop occ_name
        ; bindIfaceTyVars tv_bndrs $ \ tyvars -> do
 
   = do { tc_name <- lookupIfaceTop occ_name
        ; bindIfaceTyVars tv_bndrs $ \ tyvars -> do
 

@@ -385,25 +384,30 @@ tcIfaceDecl _
        ; return (ATyCon tycon)
     }}
 
        ; return (ATyCon tycon)
     }}
 

-tcIfaceDecl _
-           (IfaceSyn {ifName = occ_name, ifTyVars = tv_bndrs, 
-                      ifOpenSyn = isOpen, ifSynRhs = rdr_rhs_ty,
-                      ifFamInst = mb_family})
+tcIfaceDecl _ (IfaceSyn {ifName = occ_name, ifTyVars = tv_bndrs, 
+                        ifSynRhs = mb_rhs_ty,
+                        ifSynKind = kind, ifFamInst = mb_family})

    = bindIfaceTyVars tv_bndrs $ \ tyvars -> do
      { tc_name <- lookupIfaceTop occ_name
    = bindIfaceTyVars tv_bndrs $ \ tyvars -> do
      { tc_name <- lookupIfaceTop occ_name

-     ; rhs_tyki <- tcIfaceType rdr_rhs_ty
-     ; let rhs = if isOpen then OpenSynTyCon rhs_tyki Nothing
-                          else SynonymTyCon rhs_tyki
-     ; famInst <- case mb_family of
-                   Nothing         -> return Nothing
-                   Just (fam, tys) -> 
-                     do { famTyCon <- tcIfaceTyCon fam
-                        ; insttys <- mapM tcIfaceType tys
-                        ; return $ Just (famTyCon, insttys)
-                        }
-     ; tycon <- buildSynTyCon tc_name tyvars rhs famInst
+     ; rhs_kind <- tcIfaceType kind    -- Note [Synonym kind loop]
+     ; ~(rhs, fam) <- forkM (mk_doc tc_name) $ 
+                             do { rhs <- tc_syn_rhs rhs_kind mb_rhs_ty
+                        ; fam <- tc_syn_fam mb_family
+                        ; return (rhs, fam) }
+     ; tycon <- buildSynTyCon tc_name tyvars rhs rhs_kind fam

      ; return $ ATyCon tycon
      }
      ; return $ ATyCon tycon
      }

+   where
+     mk_doc n = ptext (sLit "Type syonym") <+> ppr n
+     tc_syn_rhs kind Nothing   = return (OpenSynTyCon kind Nothing)
+     tc_syn_rhs _    (Just ty) = do { rhs_ty <- tcIfaceType ty
+                                   ; return (SynonymTyCon rhs_ty) }
+     tc_syn_fam Nothing 
+       = return Nothing
+     tc_syn_fam (Just (fam, tys)) 
+       = do { famTyCon <- tcIfaceTyCon fam
+           ; insttys <- mapM tcIfaceType tys
+                   ; return $ Just (famTyCon, insttys) }

 
 tcIfaceDecl ignore_prags
            (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, 
 
 tcIfaceDecl ignore_prags
            (IfaceClass {ifCtxt = rdr_ctxt, ifName = occ_name, 

@@ -505,6 +509,23 @@ tcIfaceEqSpec spec
                               ; return (tv,ty) }
 \end{code}
 
                               ; return (tv,ty) }
 \end{code}
 

+Note [Synonym kind loop]
+~~~~~~~~~~~~~~~~~~~~~~~~
+Notice that we eagerly grab the *kind* from the interface file, but
+build a forkM thunk for the *rhs* (and family stuff).  To see why, 
+consider this (Trac #2412)
+
+M.hs:       module M where { import X; data T = MkT S }
+X.hs:       module X where { import {-# SOURCE #-} M; type S = T }
+M.hs-boot:  module M where { data T }
+
+When kind-checking M.hs we need S's kind.  But we do not want to
+find S's kind from (typeKind S-rhs), because we don't want to look at
+S-rhs yet!  Since S is imported from X.hi, S gets just one chance to
+be defined, and we must not do that until we've finished with M.T.
+
+Solution: record S's kind in the interface file; now we can safely
+look at it.

 
 %************************************************************************
 %*                                                                     *
 
 %************************************************************************
 %*                                                                     *

@@ -880,6 +901,7 @@ tcIdInfo ignore_prags name ty info
     -- we start; default assumption is that it has CAFs
     init_info = vanillaIdInfo
 
     -- we start; default assumption is that it has CAFs
     init_info = vanillaIdInfo
 

+    tcPrag :: IdInfo -> IfaceInfoItem -> IfL IdInfo

     tcPrag info HsNoCafRefs         = return (info `setCafInfo`   NoCafRefs)
     tcPrag info (HsArity arity)     = return (info `setArityInfo` arity)
     tcPrag info (HsStrictness str)  = return (info `setAllStrictnessInfo` Just str)
     tcPrag info HsNoCafRefs         = return (info `setCafInfo`   NoCafRefs)
     tcPrag info (HsArity arity)     = return (info `setArityInfo` arity)
     tcPrag info (HsStrictness str)  = return (info `setAllStrictnessInfo` Just str)

@@ -985,9 +1007,9 @@ tcIfaceGlobal name
 
          ; _ -> do
 
 
          ; _ -> do
 

-       { (eps,hpt) <- getEpsAndHpt
-       ; dflags <- getDOpts
-       ; case lookupType dflags hpt (eps_PTE eps) name of {
+       { hsc_env <- getTopEnv
+        ; mb_thing <- liftIO (lookupTypeHscEnv hsc_env name)
+       ; case mb_thing of {

            Just thing -> return thing ;
            Nothing    -> do
 
            Just thing -> return thing ;
            Nothing    -> do
 

@@ -1125,13 +1147,13 @@ newExtCoreBndr (IfLetBndr var ty _)    -- Ignoring IdInfo for now
 -----------------------
 bindIfaceTyVar :: IfaceTvBndr -> (TyVar -> IfL a) -> IfL a
 bindIfaceTyVar (occ,kind) thing_inside
 -----------------------
 bindIfaceTyVar :: IfaceTvBndr -> (TyVar -> IfL a) -> IfL a
 bindIfaceTyVar (occ,kind) thing_inside

-  = do { name <- newIfaceName (mkTyVarOcc occ)
+  = do { name <- newIfaceName (mkTyVarOccFS occ)

        ; tyvar <- mk_iface_tyvar name kind
        ; extendIfaceTyVarEnv [tyvar] (thing_inside tyvar) }
 
 bindIfaceTyVars :: [IfaceTvBndr] -> ([TyVar] -> IfL a) -> IfL a
 bindIfaceTyVars bndrs thing_inside
        ; tyvar <- mk_iface_tyvar name kind
        ; extendIfaceTyVarEnv [tyvar] (thing_inside tyvar) }
 
 bindIfaceTyVars :: [IfaceTvBndr] -> ([TyVar] -> IfL a) -> IfL a
 bindIfaceTyVars bndrs thing_inside

-  = do { names <- newIfaceNames (map mkTyVarOcc occs)
+  = do { names <- newIfaceNames (map mkTyVarOccFS occs)

        ; tyvars <- zipWithM mk_iface_tyvar names kinds
        ; extendIfaceTyVarEnv tyvars (thing_inside tyvars) }
   where
        ; tyvars <- zipWithM mk_iface_tyvar names kinds
        ; extendIfaceTyVarEnv tyvars (thing_inside tyvars) }
   where