Another round of External Core fixes

[ghc-hetmet.git] / compiler / typecheck / TcEnv.lhs

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index ac55f4b..1f9d305 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -35,7 +35,6 @@ module TcEnv(
        tcLookupId, tcLookupTyVar, getScopedTyVarBinds,
        lclEnvElts, getInLocalScope, findGlobals, 
        wrongThingErr, pprBinders,
-       refineEnvironment,
 
        tcExtendRecEnv,         -- For knot-tying
 
@@ -61,7 +60,6 @@ import IfaceEnv
 import TcRnMonad
 import TcMType
 import TcType
-import TcGadt
 -- import TcSuspension
 import qualified Type
 import Var
@@ -83,6 +81,7 @@ import HscTypes
 import SrcLoc
 import Outputable
 import Maybes
+import FastString
 \end{code}
 
 
@@ -135,10 +134,22 @@ tcLookupGlobal name
 
 tcLookupField :: Name -> TcM Id                -- Returns the selector Id
 tcLookupField name = do
-    thing <- tcLookupGlobal name
+    thing <- tcLookup name     -- Note [Record field lookup]
     case thing of
-       AnId id -> return id
-       other   -> wrongThingErr "field name" (AGlobal thing) name
+       AGlobal (AnId id) -> return id
+       thing -> wrongThingErr "field name" thing name
+
+{- Note [Record field lookup]
+   ~~~~~~~~~~~~~~~~~~~~~~~~~~
+You might think we should have tcLookupGlobal here, since record fields
+are always top level.  But consider
+       f = e { f = True }
+Then the renamer (which does not keep track of what is a record selector
+and what is not) will rename the definition thus
+       f_7 = e { f_7 = True }
+Now the type checker will find f_7 in the *local* type environment, not
+the global one. It's wrong, of course, but we want to report a tidy
+error, not in TcEnv.notFound.  -}
 
 tcLookupDataCon :: Name -> TcM DataCon
 tcLookupDataCon name = do
@@ -452,38 +463,6 @@ find_thing ignore_it tidy_env (ATyVar tv ty) = do
 find_thing _ _ thing = pprPanic "find_thing" (ppr thing)
 \end{code}
 
-\begin{code}
-refineEnvironment 
-       :: Refinement 
-       -> Bool                 -- whether type equations are involved
-       -> TcM a 
-       -> TcM a
--- I don't think I have to refine the set of global type variables in scope
--- Reason: the refinement never increases that set
-refineEnvironment reft otherEquations thing_inside
-  | isEmptyRefinement reft     -- Common case
-  , not otherEquations
-  = thing_inside
-  | otherwise
-  = do { env <- getLclEnv
-       ; let le' = mapNameEnv refine (tcl_env env)
-       ; setLclEnv (env {tcl_env = le'}) thing_inside }
-  where
-    refine elt@(ATcId { tct_co = Rigid co, tct_type = ty })
-       | Just (co', ty') <- refineType reft ty
-       = elt { tct_co = Rigid (WpCo co' <.> co), tct_type = ty' }
-    refine elt@(ATcId { tct_co = Wobbly})
--- Main new idea: make wobbly things invisible whenever there 
---               is a refinement of any sort
---     | otherEquations
-       = elt { tct_co = WobblyInvisible}
-    refine (ATyVar tv ty) 
-       | Just (_, ty') <- refineType reft ty
-       = ATyVar tv ty' -- Ignore the coercion that refineType returns
-
-    refine elt = elt   -- Common case
-\end{code}
-
 %************************************************************************
 %*                                                                     *
 \subsection{The global tyvars}