X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcSplice.lhs;h=f68239ee26e8e267af6f222d3ad3d74df4b98b54;hb=191292aaa7f56f32fc546478f43aa89ac67c95a3;hp=b96307d215521d7360e090d3066aabf7338fc6dd;hpb=debb7b80e707c343a3a7d8993ffab19b83e5c52b;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcSplice.lhs b/compiler/typecheck/TcSplice.lhs
index b96307d..f68239e 100644
--- a/compiler/typecheck/TcSplice.lhs
+++ b/compiler/typecheck/TcSplice.lhs
@@ -343,16 +343,29 @@ tcBracket brack res_ty
        ; lie_var <- getConstraintVar
        ; let brack_stage = Brack cur_stage pending_splices lie_var
 
-       ; (meta_ty, lie) <- setStage brack_stage $
-                           captureConstraints $
-                           tc_bracket cur_stage brack
-
-       ; simplifyBracket lie
-
-	-- Make the expected type have the right shape
-       ; _ <- unifyType meta_ty res_ty
-
-	-- Return the original expression, not the type-decorated one
+          -- We want to check that there aren't any constraints that
+          -- can't be satisfied (e.g. Show Foo, where Foo has no Show
+          -- instance), but we aren't otherwise interested in the
+          -- results. Nor do we care about ambiguous dictionaries etc.
+          -- We will type check this bracket again at its usage site.
+	  --
+	  -- We build a single implication constraint with a BracketSkol;
+	  -- that in turn tells simplifyCheck to report only definite
+	  -- errors
+       ; (_,lie) <- captureConstraints $
+              	    newImplication BracketSkol [] [] $
+              	    setStage brack_stage $
+              	    do { meta_ty <- tc_bracket cur_stage brack
+              	       ; unifyType meta_ty res_ty }
+
+          -- It's best to simplify the constraint now, even though in 
+	  -- principle some later unification might be useful for it,
+	  -- because we don't want these essentially-junk TH implication
+	  -- contraints floating around nested inside other constraints
+	  -- See for example Trac #4949
+       ; _ <- simplifyTop lie
+
+        -- Return the original expression, not the type-decorated one
        ; pendings <- readMutVar pending_splices
        ; return (noLoc (HsBracketOut brack pendings)) }
 
@@ -373,7 +386,7 @@ tc_bracket outer_stage (VarBr name) 	-- Note [Quoting names]
 	}
 
 tc_bracket _ (ExpBr expr) 
-  = do	{ any_ty <- newFlexiTyVarTy liftedTypeKind
+  = do	{ any_ty <- newFlexiTyVarTy openTypeKind
 	; _ <- tcMonoExprNC expr any_ty  -- NC for no context; tcBracket does that
 	; tcMetaTy expQTyConName }
 	-- Result type is ExpQ (= Q Exp)
@@ -394,8 +407,8 @@ tc_bracket _ (DecBrG decls)
 	; tcMetaTy decsQTyConName } -- Result type is Q [Dec]
 
 tc_bracket _ (PatBr pat)
-  = do	{ any_ty <- newFlexiTyVarTy liftedTypeKind
-	; _ <- tcPat ThPatQuote pat any_ty unitTy $ 
+  = do	{ any_ty <- newFlexiTyVarTy openTypeKind
+	; _ <- tcPat ThPatQuote pat any_ty $ 
                return ()
 	; tcMetaTy patQTyConName }
 	-- Result type is PatQ (= Q Pat)
@@ -664,7 +677,17 @@ runQuasiQuote :: Outputable hs_syn
               -> MetaOps th_syn hs_syn 
               -> RnM hs_syn
 runQuasiQuote (HsQuasiQuote quoter q_span quote) quote_selector meta_ty meta_ops
-  = do	{ quoter' <- lookupOccRn quoter
+  = do  {     -- Drop the leading "$" from the quoter name, if present
+              -- This is old-style syntax, now deprecated
+              -- NB: when removing this backward-compat, remove
+              --     the matching code in Lexer.x (around line 310)
+          let occ_str = occNameString (rdrNameOcc quoter)
+        ; quoter <- ASSERT( not (null occ_str) )  -- Lexer ensures this
+                    if head occ_str /= '$' then return quoter
+                    else do { addWarn (deprecatedDollar quoter)
+                            ; return (mkRdrUnqual (mkVarOcc (tail occ_str))) }
+
+        ; quoter' <- lookupOccRn quoter
 		-- We use lookupOcc rather than lookupGlobalOcc because in the
 		-- erroneous case of \x -> [x| ...|] we get a better error message
 		-- (stage restriction rather than out of scope).
@@ -709,6 +732,12 @@ quoteStageError :: Name -> SDoc
 quoteStageError quoter
   = sep [ptext (sLit "GHC stage restriction:") <+> ppr quoter,
          nest 2 (ptext (sLit "is used in a quasiquote, and must be imported, not defined locally"))]
+
+deprecatedDollar :: RdrName -> SDoc
+deprecatedDollar quoter
+  = hang (ptext (sLit "Deprecated syntax:"))
+       2 (ptext (sLit "quasiquotes no longer need a dollar sign:")
+          <+> ppr quoter)
 \end{code}
 
 
@@ -787,7 +816,7 @@ runMeta show_code run_and_convert expr
 	; hsc_env <- getTopEnv
 	; src_span <- getSrcSpanM
 	; either_hval <- tryM $ liftIO $
-			 HscMain.compileExpr hsc_env src_span ds_expr
+			 HscMain.hscCompileCoreExpr hsc_env src_span ds_expr
 	; case either_hval of {
 	    Left exn   -> failWithTc (mk_msg "compile and link" exn) ;
 	    Right hval -> do
@@ -924,11 +953,11 @@ illegalBracket = ptext (sLit "Template Haskell brackets cannot be nested (withou
 %************************************************************************
 
 \begin{code}
-lookupClassInstances :: TH.Name -> [TH.Type] -> TcM [TH.Name]
+lookupClassInstances :: TH.Name -> [TH.Type] -> TcM [TH.ClassInstance]
 lookupClassInstances c ts
    = do { loc <- getSrcSpanM
-        ; case convertToHsPred loc (TH.ClassP c ts) of
-            Left msg -> failWithTc msg
+        ; case convertToHsPred loc (TH.ClassP c ts) of {
+            Left msg -> failWithTc msg;
             Right rdr_pred -> do
         { rn_pred <- rnLPred doc rdr_pred	-- Rename
         ; kc_pred <- kcHsLPred rn_pred		-- Kind check
@@ -937,8 +966,7 @@ lookupClassInstances c ts
 	-- Now look up instances
         ; inst_envs <- tcGetInstEnvs
         ; let (matches, unifies) = lookupInstEnv inst_envs cls tys
-              dfuns = map is_dfun (map fst matches ++ unifies)
-        ; return (map reifyName dfuns) } }
+        ; mapM reifyClassInstance (map fst matches ++ unifies) } } }
   where
     doc = ptext (sLit "TcSplice.classInstances")
 \end{code}