diff options
Diffstat (limited to 'compiler/rename/RnExpr.lhs')
| -rw-r--r-- | compiler/rename/RnExpr.lhs | 996 |
1 files changed, 996 insertions, 0 deletions
diff --git a/compiler/rename/RnExpr.lhs b/compiler/rename/RnExpr.lhs new file mode 100644 index 0000000000..716a85a3b3 --- /dev/null +++ b/compiler/rename/RnExpr.lhs @@ -0,0 +1,996 @@ +% +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% +\section[RnExpr]{Renaming of expressions} + +Basically dependency analysis. + +Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In +general, all of these functions return a renamed thing, and a set of +free variables. + +\begin{code} +module RnExpr ( + rnLExpr, rnExpr, rnStmts + ) where + +#include "HsVersions.h" + +import RnSource ( rnSrcDecls, rnSplice, checkTH ) +import RnBinds ( rnLocalBindsAndThen, rnValBinds, + rnMatchGroup, trimWith ) +import HsSyn +import RnHsSyn +import TcRnMonad +import RnEnv +import OccName ( plusOccEnv ) +import RnNames ( getLocalDeclBinders, extendRdrEnvRn ) +import RnTypes ( rnHsTypeFVs, rnLPat, rnOverLit, rnPatsAndThen, rnLit, + mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec, + dupFieldErr, checkTupSize ) +import DynFlags ( DynFlag(..) ) +import BasicTypes ( FixityDirection(..) ) +import PrelNames ( thFAKE, hasKey, assertIdKey, assertErrorName, + loopAName, choiceAName, appAName, arrAName, composeAName, firstAName, + negateName, thenMName, bindMName, failMName ) +#if defined(GHCI) && defined(BREAKPOINT) +import PrelNames ( breakpointJumpName, undefined_RDR, breakpointIdKey ) +import UniqFM ( eltsUFM ) +import DynFlags ( GhcMode(..) ) +import SrcLoc ( srcSpanFile, srcSpanStartLine ) +import Name ( isTyVarName ) +#endif +import Name ( Name, nameOccName, nameIsLocalOrFrom ) +import NameSet +import RdrName ( RdrName, emptyGlobalRdrEnv, extendLocalRdrEnv, lookupLocalRdrEnv ) +import LoadIface ( loadHomeInterface ) +import UniqFM ( isNullUFM ) +import UniqSet ( emptyUniqSet ) +import List ( nub ) +import Util ( isSingleton ) +import ListSetOps ( removeDups ) +import Maybes ( expectJust ) +import Outputable +import SrcLoc ( Located(..), unLoc, getLoc, cmpLocated ) +import FastString + +import List ( unzip4 ) +\end{code} + + +%************************************************************************ +%* * +\subsubsection{Expressions} +%* * +%************************************************************************ + +\begin{code} +rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars) +rnExprs ls = rnExprs' ls emptyUniqSet + where + rnExprs' [] acc = returnM ([], acc) + rnExprs' (expr:exprs) acc + = rnLExpr expr `thenM` \ (expr', fvExpr) -> + + -- Now we do a "seq" on the free vars because typically it's small + -- or empty, especially in very long lists of constants + let + acc' = acc `plusFV` fvExpr + in + (grubby_seqNameSet acc' rnExprs') exprs acc' `thenM` \ (exprs', fvExprs) -> + returnM (expr':exprs', fvExprs) + +-- Grubby little function to do "seq" on namesets; replace by proper seq when GHC can do seq +grubby_seqNameSet ns result | isNullUFM ns = result + | otherwise = result +\end{code} + +Variables. We look up the variable and return the resulting name. + +\begin{code} +rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars) +rnLExpr = wrapLocFstM rnExpr + +rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars) + +rnExpr (HsVar v) + = do name <- lookupOccRn v + localRdrEnv <- getLocalRdrEnv + lclEnv <- getLclEnv + ignore_asserts <- doptM Opt_IgnoreAsserts + ignore_breakpoints <- doptM Opt_IgnoreBreakpoints + let conds = [ (name `hasKey` assertIdKey + && not ignore_asserts, + do (e, fvs) <- mkAssertErrorExpr + return (e, fvs `addOneFV` name)) +#if defined(GHCI) && defined(BREAKPOINT) + , (name `hasKey` breakpointIdKey + && not ignore_breakpoints, + do ghcMode <- getGhcMode + case ghcMode of + Interactive + -> do let isWantedName = not.isTyVarName + (e, fvs) <- mkBreakPointExpr (filter isWantedName (eltsUFM localRdrEnv)) + return (e, fvs `addOneFV` name) + _ -> return (HsVar name, unitFV name) + ) +#endif + ] + case lookup True conds of + Just action -> action + Nothing -> return (HsVar name, unitFV name) + +rnExpr (HsIPVar v) + = newIPNameRn v `thenM` \ name -> + returnM (HsIPVar name, emptyFVs) + +rnExpr (HsLit lit) + = rnLit lit `thenM_` + returnM (HsLit lit, emptyFVs) + +rnExpr (HsOverLit lit) + = rnOverLit lit `thenM` \ (lit', fvs) -> + returnM (HsOverLit lit', fvs) + +rnExpr (HsApp fun arg) + = rnLExpr fun `thenM` \ (fun',fvFun) -> + rnLExpr arg `thenM` \ (arg',fvArg) -> + returnM (HsApp fun' arg', fvFun `plusFV` fvArg) + +rnExpr (OpApp e1 op _ e2) + = rnLExpr e1 `thenM` \ (e1', fv_e1) -> + rnLExpr e2 `thenM` \ (e2', fv_e2) -> + rnLExpr op `thenM` \ (op'@(L _ (HsVar op_name)), fv_op) -> + + -- Deal with fixity + -- When renaming code synthesised from "deriving" declarations + -- we used to avoid fixity stuff, but we can't easily tell any + -- more, so I've removed the test. Adding HsPars in TcGenDeriv + -- should prevent bad things happening. + lookupFixityRn op_name `thenM` \ fixity -> + mkOpAppRn e1' op' fixity e2' `thenM` \ final_e -> + + returnM (final_e, + fv_e1 `plusFV` fv_op `plusFV` fv_e2) + +rnExpr (NegApp e _) + = rnLExpr e `thenM` \ (e', fv_e) -> + lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) -> + mkNegAppRn e' neg_name `thenM` \ final_e -> + returnM (final_e, fv_e `plusFV` fv_neg) + +rnExpr (HsPar e) + = rnLExpr e `thenM` \ (e', fvs_e) -> + returnM (HsPar e', fvs_e) + +-- Template Haskell extensions +-- Don't ifdef-GHCI them because we want to fail gracefully +-- (not with an rnExpr crash) in a stage-1 compiler. +rnExpr e@(HsBracket br_body) + = checkTH e "bracket" `thenM_` + rnBracket br_body `thenM` \ (body', fvs_e) -> + returnM (HsBracket body', fvs_e) + +rnExpr e@(HsSpliceE splice) + = rnSplice splice `thenM` \ (splice', fvs) -> + returnM (HsSpliceE splice', fvs) + +rnExpr section@(SectionL expr op) + = rnLExpr expr `thenM` \ (expr', fvs_expr) -> + rnLExpr op `thenM` \ (op', fvs_op) -> + checkSectionPrec InfixL section op' expr' `thenM_` + returnM (SectionL expr' op', fvs_op `plusFV` fvs_expr) + +rnExpr section@(SectionR op expr) + = rnLExpr op `thenM` \ (op', fvs_op) -> + rnLExpr expr `thenM` \ (expr', fvs_expr) -> + checkSectionPrec InfixR section op' expr' `thenM_` + returnM (SectionR op' expr', fvs_op `plusFV` fvs_expr) + +rnExpr (HsCoreAnn ann expr) + = rnLExpr expr `thenM` \ (expr', fvs_expr) -> + returnM (HsCoreAnn ann expr', fvs_expr) + +rnExpr (HsSCC lbl expr) + = rnLExpr expr `thenM` \ (expr', fvs_expr) -> + returnM (HsSCC lbl expr', fvs_expr) + +rnExpr (HsLam matches) + = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) -> + returnM (HsLam matches', fvMatch) + +rnExpr (HsCase expr matches) + = rnLExpr expr `thenM` \ (new_expr, e_fvs) -> + rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) -> + returnM (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs) + +rnExpr (HsLet binds expr) + = rnLocalBindsAndThen binds $ \ binds' -> + rnLExpr expr `thenM` \ (expr',fvExpr) -> + returnM (HsLet binds' expr', fvExpr) + +rnExpr e@(HsDo do_or_lc stmts body _) + = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $ + rnLExpr body + ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) } + +rnExpr (ExplicitList _ exps) + = rnExprs exps `thenM` \ (exps', fvs) -> + returnM (ExplicitList placeHolderType exps', fvs `addOneFV` listTyCon_name) + +rnExpr (ExplicitPArr _ exps) + = rnExprs exps `thenM` \ (exps', fvs) -> + returnM (ExplicitPArr placeHolderType exps', fvs) + +rnExpr e@(ExplicitTuple exps boxity) + = checkTupSize tup_size `thenM_` + rnExprs exps `thenM` \ (exps', fvs) -> + returnM (ExplicitTuple exps' boxity, fvs `addOneFV` tycon_name) + where + tup_size = length exps + tycon_name = tupleTyCon_name boxity tup_size + +rnExpr (RecordCon con_id _ rbinds) + = lookupLocatedOccRn con_id `thenM` \ conname -> + rnRbinds "construction" rbinds `thenM` \ (rbinds', fvRbinds) -> + returnM (RecordCon conname noPostTcExpr rbinds', + fvRbinds `addOneFV` unLoc conname) + +rnExpr (RecordUpd expr rbinds _ _) + = rnLExpr expr `thenM` \ (expr', fvExpr) -> + rnRbinds "update" rbinds `thenM` \ (rbinds', fvRbinds) -> + returnM (RecordUpd expr' rbinds' placeHolderType placeHolderType, + fvExpr `plusFV` fvRbinds) + +rnExpr (ExprWithTySig expr pty) + = rnLExpr expr `thenM` \ (expr', fvExpr) -> + rnHsTypeFVs doc pty `thenM` \ (pty', fvTy) -> + returnM (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) + where + doc = text "In an expression type signature" + +rnExpr (HsIf p b1 b2) + = rnLExpr p `thenM` \ (p', fvP) -> + rnLExpr b1 `thenM` \ (b1', fvB1) -> + rnLExpr b2 `thenM` \ (b2', fvB2) -> + returnM (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2]) + +rnExpr (HsType a) + = rnHsTypeFVs doc a `thenM` \ (t, fvT) -> + returnM (HsType t, fvT) + where + doc = text "In a type argument" + +rnExpr (ArithSeq _ seq) + = rnArithSeq seq `thenM` \ (new_seq, fvs) -> + returnM (ArithSeq noPostTcExpr new_seq, fvs) + +rnExpr (PArrSeq _ seq) + = rnArithSeq seq `thenM` \ (new_seq, fvs) -> + returnM (PArrSeq noPostTcExpr new_seq, fvs) +\end{code} + +These three are pattern syntax appearing in expressions. +Since all the symbols are reservedops we can simply reject them. +We return a (bogus) EWildPat in each case. + +\begin{code} +rnExpr e@EWildPat = patSynErr e +rnExpr e@(EAsPat {}) = patSynErr e +rnExpr e@(ELazyPat {}) = patSynErr e +\end{code} + +%************************************************************************ +%* * + Arrow notation +%* * +%************************************************************************ + +\begin{code} +rnExpr (HsProc pat body) + = newArrowScope $ + rnPatsAndThen ProcExpr [pat] $ \ [pat'] -> + rnCmdTop body `thenM` \ (body',fvBody) -> + returnM (HsProc pat' body', fvBody) + +rnExpr (HsArrApp arrow arg _ ho rtl) + = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) -> + rnLExpr arg `thenM` \ (arg',fvArg) -> + returnM (HsArrApp arrow' arg' placeHolderType ho rtl, + fvArrow `plusFV` fvArg) + where + select_arrow_scope tc = case ho of + HsHigherOrderApp -> tc + HsFirstOrderApp -> escapeArrowScope tc + +-- infix form +rnExpr (HsArrForm op (Just _) [arg1, arg2]) + = escapeArrowScope (rnLExpr op) + `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) -> + rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) -> + rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) -> + + -- Deal with fixity + + lookupFixityRn op_name `thenM` \ fixity -> + mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e -> + + returnM (final_e, + fv_arg1 `plusFV` fv_op `plusFV` fv_arg2) + +rnExpr (HsArrForm op fixity cmds) + = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) -> + rnCmdArgs cmds `thenM` \ (cmds',fvCmds) -> + returnM (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds) + +rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other) + -- DictApp, DictLam, TyApp, TyLam +\end{code} + + +%************************************************************************ +%* * + Arrow commands +%* * +%************************************************************************ + +\begin{code} +rnCmdArgs [] = returnM ([], emptyFVs) +rnCmdArgs (arg:args) + = rnCmdTop arg `thenM` \ (arg',fvArg) -> + rnCmdArgs args `thenM` \ (args',fvArgs) -> + returnM (arg':args', fvArg `plusFV` fvArgs) + + +rnCmdTop = wrapLocFstM rnCmdTop' + where + rnCmdTop' (HsCmdTop cmd _ _ _) + = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) -> + let + cmd_names = [arrAName, composeAName, firstAName] ++ + nameSetToList (methodNamesCmd (unLoc cmd')) + in + -- Generate the rebindable syntax for the monad + lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) -> + + returnM (HsCmdTop cmd' [] placeHolderType cmd_names', + fvCmd `plusFV` cmd_fvs) + +--------------------------------------------------- +-- convert OpApp's in a command context to HsArrForm's + +convertOpFormsLCmd :: LHsCmd id -> LHsCmd id +convertOpFormsLCmd = fmap convertOpFormsCmd + +convertOpFormsCmd :: HsCmd id -> HsCmd id + +convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e +convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match) +convertOpFormsCmd (OpApp c1 op fixity c2) + = let + arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType [] + arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType [] + in + HsArrForm op (Just fixity) [arg1, arg2] + +convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c) + +-- gaw 2004 +convertOpFormsCmd (HsCase exp matches) + = HsCase exp (convertOpFormsMatch matches) + +convertOpFormsCmd (HsIf exp c1 c2) + = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2) + +convertOpFormsCmd (HsLet binds cmd) + = HsLet binds (convertOpFormsLCmd cmd) + +convertOpFormsCmd (HsDo ctxt stmts body ty) + = HsDo ctxt (map (fmap convertOpFormsStmt) stmts) + (convertOpFormsLCmd body) ty + +-- Anything else is unchanged. This includes HsArrForm (already done), +-- things with no sub-commands, and illegal commands (which will be +-- caught by the type checker) +convertOpFormsCmd c = c + +convertOpFormsStmt (BindStmt pat cmd _ _) + = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr +convertOpFormsStmt (ExprStmt cmd _ _) + = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType +convertOpFormsStmt (RecStmt stmts lvs rvs es binds) + = RecStmt (map (fmap convertOpFormsStmt) stmts) lvs rvs es binds +convertOpFormsStmt stmt = stmt + +convertOpFormsMatch (MatchGroup ms ty) + = MatchGroup (map (fmap convert) ms) ty + where convert (Match pat mty grhss) + = Match pat mty (convertOpFormsGRHSs grhss) + +convertOpFormsGRHSs (GRHSs grhss binds) + = GRHSs (map convertOpFormsGRHS grhss) binds + +convertOpFormsGRHS = fmap convert + where + convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd) + +--------------------------------------------------- +type CmdNeeds = FreeVars -- Only inhabitants are + -- appAName, choiceAName, loopAName + +-- find what methods the Cmd needs (loop, choice, apply) +methodNamesLCmd :: LHsCmd Name -> CmdNeeds +methodNamesLCmd = methodNamesCmd . unLoc + +methodNamesCmd :: HsCmd Name -> CmdNeeds + +methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsFirstOrderApp _rtl) + = emptyFVs +methodNamesCmd cmd@(HsArrApp _arrow _arg _ HsHigherOrderApp _rtl) + = unitFV appAName +methodNamesCmd cmd@(HsArrForm {}) = emptyFVs + +methodNamesCmd (HsPar c) = methodNamesLCmd c + +methodNamesCmd (HsIf p c1 c2) + = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName + +methodNamesCmd (HsLet b c) = methodNamesLCmd c + +methodNamesCmd (HsDo sc stmts body ty) + = methodNamesStmts stmts `plusFV` methodNamesLCmd body + +methodNamesCmd (HsApp c e) = methodNamesLCmd c + +methodNamesCmd (HsLam match) = methodNamesMatch match + +methodNamesCmd (HsCase scrut matches) + = methodNamesMatch matches `addOneFV` choiceAName + +methodNamesCmd other = emptyFVs + -- Other forms can't occur in commands, but it's not convenient + -- to error here so we just do what's convenient. + -- The type checker will complain later + +--------------------------------------------------- +methodNamesMatch (MatchGroup ms ty) + = plusFVs (map do_one ms) + where + do_one (L _ (Match pats sig_ty grhss)) = methodNamesGRHSs grhss + +------------------------------------------------- +-- gaw 2004 +methodNamesGRHSs (GRHSs grhss binds) = plusFVs (map methodNamesGRHS grhss) + +------------------------------------------------- +methodNamesGRHS (L _ (GRHS stmts rhs)) = methodNamesLCmd rhs + +--------------------------------------------------- +methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts) + +--------------------------------------------------- +methodNamesLStmt = methodNamesStmt . unLoc + +methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd +methodNamesStmt (BindStmt pat cmd _ _) = methodNamesLCmd cmd +methodNamesStmt (RecStmt stmts _ _ _ _) + = methodNamesStmts stmts `addOneFV` loopAName +methodNamesStmt (LetStmt b) = emptyFVs +methodNamesStmt (ParStmt ss) = emptyFVs + -- ParStmt can't occur in commands, but it's not convenient to error + -- here so we just do what's convenient +\end{code} + + +%************************************************************************ +%* * + Arithmetic sequences +%* * +%************************************************************************ + +\begin{code} +rnArithSeq (From expr) + = rnLExpr expr `thenM` \ (expr', fvExpr) -> + returnM (From expr', fvExpr) + +rnArithSeq (FromThen expr1 expr2) + = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) -> + rnLExpr expr2 `thenM` \ (expr2', fvExpr2) -> + returnM (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2) + +rnArithSeq (FromTo expr1 expr2) + = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) -> + rnLExpr expr2 `thenM` \ (expr2', fvExpr2) -> + returnM (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2) + +rnArithSeq (FromThenTo expr1 expr2 expr3) + = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) -> + rnLExpr expr2 `thenM` \ (expr2', fvExpr2) -> + rnLExpr expr3 `thenM` \ (expr3', fvExpr3) -> + returnM (FromThenTo expr1' expr2' expr3', + plusFVs [fvExpr1, fvExpr2, fvExpr3]) +\end{code} + + +%************************************************************************ +%* * +\subsubsection{@Rbinds@s and @Rpats@s: in record expressions} +%* * +%************************************************************************ + +\begin{code} +rnRbinds str rbinds + = mappM_ field_dup_err dup_fields `thenM_` + mapFvRn rn_rbind rbinds `thenM` \ (rbinds', fvRbind) -> + returnM (rbinds', fvRbind) + where + (_, dup_fields) = removeDups cmpLocated [ f | (f,_) <- rbinds ] + + field_dup_err dups = mappM_ (\f -> addLocErr f (dupFieldErr str)) dups + + rn_rbind (field, expr) + = lookupLocatedGlobalOccRn field `thenM` \ fieldname -> + rnLExpr expr `thenM` \ (expr', fvExpr) -> + returnM ((fieldname, expr'), fvExpr `addOneFV` unLoc fieldname) +\end{code} + +%************************************************************************ +%* * + Template Haskell brackets +%* * +%************************************************************************ + +\begin{code} +rnBracket (VarBr n) = do { name <- lookupOccRn n + ; this_mod <- getModule + ; checkM (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the + do { loadHomeInterface msg name -- home interface is loaded, and this is the + ; return () } -- only way that is going to happen + ; returnM (VarBr name, unitFV name) } + where + msg = ptext SLIT("Need interface for Template Haskell quoted Name") + +rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e + ; return (ExpBr e', fvs) } +rnBracket (PatBr p) = do { (p', fvs) <- rnLPat p + ; return (PatBr p', fvs) } +rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t + ; return (TypBr t', fvs) } + where + doc = ptext SLIT("In a Template-Haskell quoted type") +rnBracket (DecBr group) + = do { gbl_env <- getGblEnv + + ; let gbl_env1 = gbl_env { tcg_mod = thFAKE } + -- Note the thFAKE. The top-level names from the bracketed + -- declarations will go into the name cache, and we don't want them to + -- confuse the Names for the current module. + -- By using a pretend module, thFAKE, we keep them safely out of the way. + + ; names <- getLocalDeclBinders gbl_env1 group + ; rdr_env' <- extendRdrEnvRn emptyGlobalRdrEnv names + -- Furthermore, the names in the bracket shouldn't conflict with + -- existing top-level names E.g. + -- foo = 1 + -- bar = [d| foo = 1|] + -- But both 'foo's get a LocalDef provenance, so we'd get a complaint unless + -- we start with an emptyGlobalRdrEnv + + ; setGblEnv (gbl_env { tcg_rdr_env = tcg_rdr_env gbl_env1 `plusOccEnv` rdr_env', + tcg_dus = emptyDUs }) $ do + -- Notice plusOccEnv, not plusGlobalRdrEnv. In this situation we want + -- to *shadow* top-level bindings. (See the 'foo' example above.) + -- If we don't shadow, we'll get an ambiguity complaint when we do + -- a lookupTopBndrRn (which uses lookupGreLocalRn) on the binder of the 'foo' + -- + -- Furthermore, arguably if the splice does define foo, that should hide + -- any foo's further out + -- + -- The emptyDUs is so that we just collect uses for this group alone + + { (tcg_env, group') <- rnSrcDecls group + -- Discard the tcg_env; it contains only extra info about fixity + ; return (DecBr group', allUses (tcg_dus tcg_env)) } } +\end{code} + +%************************************************************************ +%* * +\subsubsection{@Stmt@s: in @do@ expressions} +%* * +%************************************************************************ + +\begin{code} +rnStmts :: HsStmtContext Name -> [LStmt RdrName] + -> RnM (thing, FreeVars) + -> RnM (([LStmt Name], thing), FreeVars) + +rnStmts (MDoExpr _) = rnMDoStmts +rnStmts ctxt = rnNormalStmts ctxt + +rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName] + -> RnM (thing, FreeVars) + -> RnM (([LStmt Name], thing), FreeVars) +-- Used for cases *other* than recursive mdo +-- Implements nested scopes + +rnNormalStmts ctxt [] thing_inside + = do { (thing, fvs) <- thing_inside + ; return (([],thing), fvs) } + +rnNormalStmts ctxt (L loc stmt : stmts) thing_inside + = do { ((stmt', (stmts', thing)), fvs) + <- rnStmt ctxt stmt $ + rnNormalStmts ctxt stmts thing_inside + ; return (((L loc stmt' : stmts'), thing), fvs) } + +rnStmt :: HsStmtContext Name -> Stmt RdrName + -> RnM (thing, FreeVars) + -> RnM ((Stmt Name, thing), FreeVars) + +rnStmt ctxt (ExprStmt expr _ _) thing_inside + = do { (expr', fv_expr) <- rnLExpr expr + ; (then_op, fvs1) <- lookupSyntaxName thenMName + ; (thing, fvs2) <- thing_inside + ; return ((ExprStmt expr' then_op placeHolderType, thing), + fv_expr `plusFV` fvs1 `plusFV` fvs2) } + +rnStmt ctxt (BindStmt pat expr _ _) thing_inside + = do { (expr', fv_expr) <- rnLExpr expr + -- The binders do not scope over the expression + ; (bind_op, fvs1) <- lookupSyntaxName bindMName + ; (fail_op, fvs2) <- lookupSyntaxName failMName + ; rnPatsAndThen (StmtCtxt ctxt) [pat] $ \ [pat'] -> do + { (thing, fvs3) <- thing_inside + ; return ((BindStmt pat' expr' bind_op fail_op, thing), + fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }} + -- fv_expr shouldn't really be filtered by the rnPatsAndThen + -- but it does not matter because the names are unique + +rnStmt ctxt (LetStmt binds) thing_inside + = do { checkErr (ok ctxt binds) + (badIpBinds (ptext SLIT("a parallel list comprehension:")) binds) + ; rnLocalBindsAndThen binds $ \ binds' -> do + { (thing, fvs) <- thing_inside + ; return ((LetStmt binds', thing), fvs) }} + where + -- We do not allow implicit-parameter bindings in a parallel + -- list comprehension. I'm not sure what it might mean. + ok (ParStmtCtxt _) (HsIPBinds _) = False + ok _ _ = True + +rnStmt ctxt (RecStmt rec_stmts _ _ _ _) thing_inside + = bindLocatedLocalsRn doc (collectLStmtsBinders rec_stmts) $ \ bndrs -> + rn_rec_stmts bndrs rec_stmts `thenM` \ segs -> + thing_inside `thenM` \ (thing, fvs) -> + let + segs_w_fwd_refs = addFwdRefs segs + (ds, us, fs, rec_stmts') = unzip4 segs_w_fwd_refs + later_vars = nameSetToList (plusFVs ds `intersectNameSet` fvs) + fwd_vars = nameSetToList (plusFVs fs) + uses = plusFVs us + rec_stmt = RecStmt rec_stmts' later_vars fwd_vars [] emptyLHsBinds + in + returnM ((rec_stmt, thing), uses `plusFV` fvs) + where + doc = text "In a recursive do statement" + +rnStmt ctxt (ParStmt segs) thing_inside + = do { opt_GlasgowExts <- doptM Opt_GlasgowExts + ; checkM opt_GlasgowExts parStmtErr + ; orig_lcl_env <- getLocalRdrEnv + ; ((segs',thing), fvs) <- go orig_lcl_env [] segs + ; return ((ParStmt segs', thing), fvs) } + where +-- type ParSeg id = [([LStmt id], [id])] +-- go :: NameSet -> [ParSeg RdrName] +-- -> RnM (([ParSeg Name], thing), FreeVars) + + go orig_lcl_env bndrs [] + = do { let { (bndrs', dups) = removeDups cmpByOcc bndrs + ; inner_env = extendLocalRdrEnv orig_lcl_env bndrs' } + ; mappM dupErr dups + ; (thing, fvs) <- setLocalRdrEnv inner_env thing_inside + ; return (([], thing), fvs) } + + go orig_lcl_env bndrs_so_far ((stmts, _) : segs) + = do { ((stmts', (bndrs, segs', thing)), fvs) + <- rnNormalStmts par_ctxt stmts $ do + { -- Find the Names that are bound by stmts + lcl_env <- getLocalRdrEnv + ; let { rdr_bndrs = collectLStmtsBinders stmts + ; bndrs = map ( expectJust "rnStmt" + . lookupLocalRdrEnv lcl_env + . unLoc) rdr_bndrs + ; new_bndrs = nub bndrs ++ bndrs_so_far + -- The nub is because there might be shadowing + -- x <- e1; x <- e2 + -- So we'll look up (Unqual x) twice, getting + -- the second binding both times, which is the + } -- one we want + + -- Typecheck the thing inside, passing on all + -- the Names bound, but separately; revert the envt + ; ((segs', thing), fvs) <- setLocalRdrEnv orig_lcl_env $ + go orig_lcl_env new_bndrs segs + + -- Figure out which of the bound names are used + ; let used_bndrs = filter (`elemNameSet` fvs) bndrs + ; return ((used_bndrs, segs', thing), fvs) } + + ; let seg' = (stmts', bndrs) + ; return (((seg':segs'), thing), + delListFromNameSet fvs bndrs) } + + par_ctxt = ParStmtCtxt ctxt + + cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2 + dupErr vs = addErr (ptext SLIT("Duplicate binding in parallel list comprehension for:") + <+> quotes (ppr (head vs))) +\end{code} + + +%************************************************************************ +%* * +\subsubsection{mdo expressions} +%* * +%************************************************************************ + +\begin{code} +type FwdRefs = NameSet +type Segment stmts = (Defs, + Uses, -- May include defs + FwdRefs, -- A subset of uses that are + -- (a) used before they are bound in this segment, or + -- (b) used here, and bound in subsequent segments + stmts) -- Either Stmt or [Stmt] + + +---------------------------------------------------- +rnMDoStmts :: [LStmt RdrName] + -> RnM (thing, FreeVars) + -> RnM (([LStmt Name], thing), FreeVars) +rnMDoStmts stmts thing_inside + = -- Step1: bring all the binders of the mdo into scope + -- Remember that this also removes the binders from the + -- finally-returned free-vars + bindLocatedLocalsRn doc (collectLStmtsBinders stmts) $ \ bndrs -> + do { + -- Step 2: Rename each individual stmt, making a + -- singleton segment. At this stage the FwdRefs field + -- isn't finished: it's empty for all except a BindStmt + -- for which it's the fwd refs within the bind itself + -- (This set may not be empty, because we're in a recursive + -- context.) + segs <- rn_rec_stmts bndrs stmts + + ; (thing, fvs_later) <- thing_inside + + ; let + -- Step 3: Fill in the fwd refs. + -- The segments are all singletons, but their fwd-ref + -- field mentions all the things used by the segment + -- that are bound after their use + segs_w_fwd_refs = addFwdRefs segs + + -- Step 4: Group together the segments to make bigger segments + -- Invariant: in the result, no segment uses a variable + -- bound in a later segment + grouped_segs = glomSegments segs_w_fwd_refs + + -- Step 5: Turn the segments into Stmts + -- Use RecStmt when and only when there are fwd refs + -- Also gather up the uses from the end towards the + -- start, so we can tell the RecStmt which things are + -- used 'after' the RecStmt + (stmts', fvs) = segsToStmts grouped_segs fvs_later + + ; return ((stmts', thing), fvs) } + where + doc = text "In a recursive mdo-expression" + +--------------------------------------------- +rn_rec_stmts :: [Name] -> [LStmt RdrName] -> RnM [Segment (LStmt Name)] +rn_rec_stmts bndrs stmts = mappM (rn_rec_stmt bndrs) stmts `thenM` \ segs_s -> + returnM (concat segs_s) + +---------------------------------------------------- +rn_rec_stmt :: [Name] -> LStmt RdrName -> RnM [Segment (LStmt Name)] + -- Rename a Stmt that is inside a RecStmt (or mdo) + -- Assumes all binders are already in scope + -- Turns each stmt into a singleton Stmt + +rn_rec_stmt all_bndrs (L loc (ExprStmt expr _ _)) + = rnLExpr expr `thenM` \ (expr', fvs) -> + lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) -> + returnM [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet, + L loc (ExprStmt expr' then_op placeHolderType))] + +rn_rec_stmt all_bndrs (L loc (BindStmt pat expr _ _)) + = rnLExpr expr `thenM` \ (expr', fv_expr) -> + rnLPat pat `thenM` \ (pat', fv_pat) -> + lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) -> + lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) -> + let + bndrs = mkNameSet (collectPatBinders pat') + fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2 + in + returnM [(bndrs, fvs, bndrs `intersectNameSet` fvs, + L loc (BindStmt pat' expr' bind_op fail_op))] + +rn_rec_stmt all_bndrs (L loc (LetStmt binds@(HsIPBinds _))) + = do { addErr (badIpBinds (ptext SLIT("an mdo expression")) binds) + ; failM } + +rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds))) + = rnValBinds (trimWith all_bndrs) binds `thenM` \ (binds', du_binds) -> + returnM [(duDefs du_binds, duUses du_binds, + emptyNameSet, L loc (LetStmt (HsValBinds binds')))] + +rn_rec_stmt all_bndrs (L loc (RecStmt stmts _ _ _ _)) -- Flatten Rec inside Rec + = rn_rec_stmts all_bndrs stmts + +rn_rec_stmt all_bndrs stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo + = pprPanic "rn_rec_stmt" (ppr stmt) + +--------------------------------------------- +addFwdRefs :: [Segment a] -> [Segment a] +-- So far the segments only have forward refs *within* the Stmt +-- (which happens for bind: x <- ...x...) +-- This function adds the cross-seg fwd ref info + +addFwdRefs pairs + = fst (foldr mk_seg ([], emptyNameSet) pairs) + where + mk_seg (defs, uses, fwds, stmts) (segs, later_defs) + = (new_seg : segs, all_defs) + where + new_seg = (defs, uses, new_fwds, stmts) + all_defs = later_defs `unionNameSets` defs + new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs) + -- Add the downstream fwd refs here + +---------------------------------------------------- +-- Glomming the singleton segments of an mdo into +-- minimal recursive groups. +-- +-- At first I thought this was just strongly connected components, but +-- there's an important constraint: the order of the stmts must not change. +-- +-- Consider +-- mdo { x <- ...y... +-- p <- z +-- y <- ...x... +-- q <- x +-- z <- y +-- r <- x } +-- +-- Here, the first stmt mention 'y', which is bound in the third. +-- But that means that the innocent second stmt (p <- z) gets caught +-- up in the recursion. And that in turn means that the binding for +-- 'z' has to be included... and so on. +-- +-- Start at the tail { r <- x } +-- Now add the next one { z <- y ; r <- x } +-- Now add one more { q <- x ; z <- y ; r <- x } +-- Now one more... but this time we have to group a bunch into rec +-- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x } +-- Now one more, which we can add on without a rec +-- { p <- z ; +-- rec { y <- ...x... ; q <- x ; z <- y } ; +-- r <- x } +-- Finally we add the last one; since it mentions y we have to +-- glom it togeher with the first two groups +-- { rec { x <- ...y...; p <- z ; y <- ...x... ; +-- q <- x ; z <- y } ; +-- r <- x } + +glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]] + +glomSegments [] = [] +glomSegments ((defs,uses,fwds,stmt) : segs) + -- Actually stmts will always be a singleton + = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others + where + segs' = glomSegments segs + (extras, others) = grab uses segs' + (ds, us, fs, ss) = unzip4 extras + + seg_defs = plusFVs ds `plusFV` defs + seg_uses = plusFVs us `plusFV` uses + seg_fwds = plusFVs fs `plusFV` fwds + seg_stmts = stmt : concat ss + + grab :: NameSet -- The client + -> [Segment a] + -> ([Segment a], -- Needed by the 'client' + [Segment a]) -- Not needed by the client + -- The result is simply a split of the input + grab uses dus + = (reverse yeses, reverse noes) + where + (noes, yeses) = span not_needed (reverse dus) + not_needed (defs,_,_,_) = not (intersectsNameSet defs uses) + + +---------------------------------------------------- +segsToStmts :: [Segment [LStmt Name]] + -> FreeVars -- Free vars used 'later' + -> ([LStmt Name], FreeVars) + +segsToStmts [] fvs_later = ([], fvs_later) +segsToStmts ((defs, uses, fwds, ss) : segs) fvs_later + = ASSERT( not (null ss) ) + (new_stmt : later_stmts, later_uses `plusFV` uses) + where + (later_stmts, later_uses) = segsToStmts segs fvs_later + new_stmt | non_rec = head ss + | otherwise = L (getLoc (head ss)) $ + RecStmt ss (nameSetToList used_later) (nameSetToList fwds) + [] emptyLHsBinds + where + non_rec = isSingleton ss && isEmptyNameSet fwds + used_later = defs `intersectNameSet` later_uses + -- The ones needed after the RecStmt +\end{code} + +%************************************************************************ +%* * +\subsubsection{breakpoint utils} +%* * +%************************************************************************ + +\begin{code} +#if defined(GHCI) && defined(BREAKPOINT) +mkBreakPointExpr :: [Name] -> RnM (HsExpr Name, FreeVars) +mkBreakPointExpr scope + = do sloc <- getSrcSpanM + undef <- lookupOccRn undefined_RDR + let inLoc = L sloc + lHsApp x y = inLoc (HsApp x y) + mkExpr fnName args = mkExpr' fnName (reverse args) + mkExpr' fnName [] = inLoc (HsVar fnName) + mkExpr' fnName (arg:args) + = lHsApp (mkExpr' fnName args) (inLoc arg) + expr = unLoc $ mkExpr breakpointJumpName [mkScopeArg scope, HsVar undef, HsLit msg] + mkScopeArg args + = unLoc $ mkExpr undef (map HsVar args) + msg = HsString (mkFastString (unpackFS (srcSpanFile sloc) ++ ":" ++ show (srcSpanStartLine sloc))) + return (expr, emptyFVs) +#endif +\end{code} + +%************************************************************************ +%* * +\subsubsection{Assertion utils} +%* * +%************************************************************************ + +\begin{code} +mkAssertErrorExpr :: RnM (HsExpr Name, FreeVars) +-- Return an expression for (assertError "Foo.hs:27") +mkAssertErrorExpr + = getSrcSpanM `thenM` \ sloc -> + let + expr = HsApp (L sloc (HsVar assertErrorName)) (L sloc (HsLit msg)) + msg = HsStringPrim (mkFastString (showSDoc (ppr sloc))) + in + returnM (expr, emptyFVs) +\end{code} + +%************************************************************************ +%* * +\subsubsection{Errors} +%* * +%************************************************************************ + +\begin{code} +patSynErr e = do { addErr (sep [ptext SLIT("Pattern syntax in expression context:"), + nest 4 (ppr e)]) + ; return (EWildPat, emptyFVs) } + +parStmtErr = addErr (ptext SLIT("Illegal parallel list comprehension: use -fglasgow-exts")) + +badIpBinds what binds + = hang (ptext SLIT("Implicit-parameter bindings illegal in") <+> what) + 2 (ppr binds) +\end{code} |