Completely new treatment of INLINE pragmas (big patch)

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

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index 1e51ee0..98e5aa5 100644 (file)
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -16,6 +16,8 @@ module TcSimplify (
 
        tcSimplifyDeriv, tcSimplifyDefault,
        bindInstsOfLocalFuns, 
+       
+        tcSimplifyStagedExpr,
 
         misMatchMsg
     ) where
@@ -58,6 +60,7 @@ import Util
 import SrcLoc
 import DynFlags
 import FastString
+
 import Control.Monad
 import Data.List
 \end{code}
@@ -707,6 +710,13 @@ tcSimplifyInfer doc tau_tvs wanted
                -- irreds2 will be empty.  But we don't want to generalise over b!
        ; let preds2 = fdPredsOfInsts irreds2   -- irreds2 is zonked
              qtvs   = grow preds2 tau_tvs2 `minusVarSet` oclose preds2 gbl_tvs2
+               ---------------------------------------------------
+               -- BUG WARNING: there's a nasty bug lurking here
+               -- fdPredsOfInsts may return preds that mention variables quantified in
+               -- one of the implication constraints in irreds2; and that is clearly wrong:
+               -- we might quantify over too many variables through accidental capture
+               ---------------------------------------------------
+
        ; let (free, irreds3) = partition (isFreeWhenInferring qtvs) irreds2
        ; extendLIEs free
 
@@ -977,7 +987,7 @@ makeImplicationBind :: InstLoc -> [TcTyVar]
 --     (ir1, .., irn) = f qtvs givens
 -- where f is (evidence for) the new implication constraint
 --     f :: forall qtvs. givens => (ir1, .., irn)
--- qtvs includes coercion variables.
+-- qtvs includes coercion variables
 --
 -- This binding must line up the 'rhs' in reduceImplication
 makeImplicationBind loc all_tvs
@@ -997,7 +1007,7 @@ makeImplicationBind loc all_tvs
              name = mkInternalName uniq (mkVarOcc "ic") span
              implic_inst = ImplicInst { tci_name = name,
                                         tci_tyvars = all_tvs, 
-                                        tci_given = (eq_givens ++ dict_givens),
+                                        tci_given = eq_givens ++ dict_givens,
                                                        -- same order as binders
                                         tci_wanted = irreds, 
                                          tci_loc = loc }
@@ -1013,16 +1023,17 @@ makeImplicationBind loc all_tvs
                     <.> mkWpTyApps eq_cotvs
                     <.> mkWpTyApps (mkTyVarTys all_tvs)
              bind | [dict_irred_id] <- dict_irred_ids  
-                   = VarBind dict_irred_id rhs
+                   = mkVarBind dict_irred_id rhs
                   | otherwise        
-                   = PatBind { pat_lhs = lpat
+                   = L span $ 
+                     PatBind { pat_lhs = lpat
                             , pat_rhs = unguardedGRHSs rhs 
                             , pat_rhs_ty = hsLPatType lpat
                             , bind_fvs = placeHolderNames 
                              }
 
        ; traceTc $ text "makeImplicationBind" <+> ppr implic_inst
-       ; return ([implic_inst], unitBag (L span bind)) 
+       ; return ([implic_inst], unitBag bind) 
         }
 
 -----------------------------------------------------------
@@ -2350,11 +2361,7 @@ reduceImplication env
               eq_cotvs = map instToVar extra_eq_givens
              dict_ids = map instToId  extra_dict_givens 
 
-                        -- Note [Always inline implication constraints]
-              wrap_inline | null dict_ids = idHsWrapper
-                          | otherwise    = WpInline
-              co         = wrap_inline
-                           <.> mkWpTyLams tvs
+              co         = mkWpTyLams tvs
                            <.> mkWpTyLams eq_cotvs
                            <.> mkWpLams dict_ids
                            <.> WpLet (binds `unionBags` bind)
@@ -2366,12 +2373,15 @@ reduceImplication env
                            . filter (not . isEqInst) 
                            $ wanteds
               payload    = mkBigLHsTup dict_bndrs
-
        
        ; traceTc (vcat [text "reduceImplication" <+> ppr name,
                         ppr simpler_implic_insts,
                         text "->" <+> ppr rhs])
-       ; return (unitBag (L loc (VarBind (instToId orig_implic) rhs)),
+       ; return (unitBag (L loc (VarBind { var_id= instToId orig_implic
+                                         , var_rhs = rhs
+                                         , var_inline = not (null dict_ids) }
+                               -- See Note [Always inline implication constraints]
+                         )),
                  simpler_implic_insts)
        } 
     }
@@ -3014,6 +3024,26 @@ tcSimplifyDefault theta = do
     doc = ptext (sLit "default declaration")
 \end{code}
 
+@tcSimplifyStagedExpr@ performs a simplification but does so at a new
+stage. This is used when typechecking annotations and splices.
+
+\begin{code}
+
+tcSimplifyStagedExpr :: ThStage -> TcM a -> TcM (a, TcDictBinds)
+-- Type check an expression that runs at a top level stage as if
+--   it were going to be spliced and then simplify it
+tcSimplifyStagedExpr stage tc_action
+  = setStage stage $ do { 
+        -- Typecheck the expression
+         (thing', lie) <- getLIE tc_action
+       
+       -- Solve the constraints
+       ; const_binds <- tcSimplifyTop lie
+       
+       ; return (thing', const_binds) }
+
+\end{code}
+
 
 %************************************************************************
 %*                                                                     *