X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Frename%2FRnBinds.lhs;h=7a0c19ea45c2fc1b4622b67a84ae8365f95a3baa;hb=9af77fa423926fbda946b31e174173d0ec5ebac8;hp=b55f6feb8cce03abc5d0e296fe26e6316006181d;hpb=00eefb90925f224c1e22963df2a00d70fe934d5f;p=ghc-hetmet.git diff --git a/ghc/compiler/rename/RnBinds.lhs b/ghc/compiler/rename/RnBinds.lhs index b55f6fe..7a0c19e 100644 --- a/ghc/compiler/rename/RnBinds.lhs +++ b/ghc/compiler/rename/RnBinds.lhs @@ -1,607 +1,557 @@ -% -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 -% -\section[RnBinds]{Renaming and dependency analysis of bindings} - -This module does renaming and dependency analysis on value bindings in -the abstract syntax. It does {\em not} do cycle-checks on class or -type-synonym declarations; those cannot be done at this stage because -they may be affected by renaming (which isn't fully worked out yet). - -\begin{code} -module RnBinds ( - rnTopBinds, rnTopMonoBinds, - rnMethodBinds, renameSigs, - rnBinds, - unknownSigErr - ) where - -#include "HsVersions.h" - -import {-# SOURCE #-} RnSource ( rnHsSigType ) - -import HsSyn -import HsBinds ( sigsForMe ) -import RdrHsSyn -import RnHsSyn -import RnMonad -import RnExpr ( rnMatch, rnGRHSs, rnPat, checkPrecMatch ) -import RnEnv ( bindLocatedLocalsRn, lookupBndrRn, lookupGlobalOccRn, - warnUnusedLocalBinds, mapFvRn, - FreeVars, emptyFVs, plusFV, plusFVs, unitFV, addOneFV, - unknownNameErr - ) -import CmdLineOpts ( opt_WarnMissingSigs ) -import Digraph ( stronglyConnComp, SCC(..) ) -import Name ( OccName, Name, nameOccName ) -import NameSet -import RdrName ( RdrName, rdrNameOcc ) -import BasicTypes ( RecFlag(..), TopLevelFlag(..) ) -import Util ( thenCmp, removeDups ) -import List ( partition ) -import ListSetOps ( minusList ) -import Bag ( bagToList ) -import FiniteMap ( lookupFM, listToFM ) -import Maybe ( isJust ) -import Outputable -\end{code} - --- ToDo: Put the annotations into the monad, so that they arrive in the proper --- place and can be used when complaining. - -The code tree received by the function @rnBinds@ contains definitions -in where-clauses which are all apparently mutually recursive, but which may -not really depend upon each other. For example, in the top level program -\begin{verbatim} -f x = y where a = x - y = x -\end{verbatim} -the definitions of @a@ and @y@ do not depend on each other at all. -Unfortunately, the typechecker cannot always check such definitions. -\footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive -definitions. In Proceedings of the International Symposium on Programming, -Toulouse, pp. 217-39. LNCS 167. Springer Verlag.} -However, the typechecker usually can check definitions in which only the -strongly connected components have been collected into recursive bindings. -This is precisely what the function @rnBinds@ does. - -ToDo: deal with case where a single monobinds binds the same variable -twice. - -The vertag tag is a unique @Int@; the tags only need to be unique -within one @MonoBinds@, so that unique-Int plumbing is done explicitly -(heavy monad machinery not needed). - -\begin{code} -type VertexTag = Int -type Cycle = [VertexTag] -type Edge = (VertexTag, VertexTag) -\end{code} - -%************************************************************************ -%* * -%* naming conventions * -%* * -%************************************************************************ - -\subsection[name-conventions]{Name conventions} - -The basic algorithm involves walking over the tree and returning a tuple -containing the new tree plus its free variables. Some functions, such -as those walking polymorphic bindings (HsBinds) and qualifier lists in -list comprehensions (@Quals@), return the variables bound in local -environments. These are then used to calculate the free variables of the -expression evaluated in these environments. - -Conventions for variable names are as follows: -\begin{itemize} -\item -new code is given a prime to distinguish it from the old. - -\item -a set of variables defined in @Exp@ is written @dvExp@ - -\item -a set of variables free in @Exp@ is written @fvExp@ -\end{itemize} - -%************************************************************************ -%* * -%* analysing polymorphic bindings (HsBinds, Bind, MonoBinds) * -%* * -%************************************************************************ - -\subsubsection[dep-HsBinds]{Polymorphic bindings} - -Non-recursive expressions are reconstructed without any changes at top -level, although their component expressions may have to be altered. -However, non-recursive expressions are currently not expected as -\Haskell{} programs, and this code should not be executed. - -Monomorphic bindings contain information that is returned in a tuple -(a @FlatMonoBindsInfo@) containing: - -\begin{enumerate} -\item -a unique @Int@ that serves as the ``vertex tag'' for this binding. - -\item -the name of a function or the names in a pattern. These are a set -referred to as @dvLhs@, the defined variables of the left hand side. - -\item -the free variables of the body. These are referred to as @fvBody@. - -\item -the definition's actual code. This is referred to as just @code@. -\end{enumerate} - -The function @nonRecDvFv@ returns two sets of variables. The first is -the set of variables defined in the set of monomorphic bindings, while the -second is the set of free variables in those bindings. - -The set of variables defined in a non-recursive binding is just the -union of all of them, as @union@ removes duplicates. However, the -free variables in each successive set of cumulative bindings is the -union of those in the previous set plus those of the newest binding after -the defined variables of the previous set have been removed. - -@rnMethodBinds@ deals only with the declarations in class and -instance declarations. It expects only to see @FunMonoBind@s, and -it expects the global environment to contain bindings for the binders -(which are all class operations). - -%************************************************************************ -%* * -%* Top-level bindings -%* * -%************************************************************************ - -@rnTopBinds@ assumes that the environment already -contains bindings for the binders of this particular binding. - -\begin{code} -rnTopBinds :: RdrNameHsBinds -> RnMS (RenamedHsBinds, FreeVars) - -rnTopBinds EmptyBinds = returnRn (EmptyBinds, emptyFVs) -rnTopBinds (MonoBind bind sigs _) = rnTopMonoBinds bind sigs - -- The parser doesn't produce other forms - - -rnTopMonoBinds EmptyMonoBinds sigs - = returnRn (EmptyBinds, emptyFVs) - -rnTopMonoBinds mbinds sigs - = mapRn lookupBndrRn binder_rdr_names `thenRn` \ binder_names -> - let - binder_set = mkNameSet binder_names - binder_occ_fm = listToFM [(nameOccName x,x) | x <- binder_names] - in - renameSigs opt_WarnMissingSigs binder_set - (lookupSigOccRn binder_occ_fm) sigs `thenRn` \ (siglist, sig_fvs) -> - rn_mono_binds siglist mbinds `thenRn` \ (final_binds, bind_fvs) -> - returnRn (final_binds, bind_fvs `plusFV` sig_fvs) - where - binder_rdr_names = map fst (bagToList (collectMonoBinders mbinds)) - --- the names appearing in the sigs have to be bound by --- this group's binders. -lookupSigOccRn binder_occ_fm rdr_name - = case lookupFM binder_occ_fm (rdrNameOcc rdr_name) of - Nothing -> failWithRn (mkUnboundName rdr_name) - (unknownNameErr rdr_name) - Just x -> returnRn x -\end{code} - -%************************************************************************ -%* * -%* Nested binds -%* * -%************************************************************************ - -@rnMonoBinds@ - - collects up the binders for this declaration group, - - checks that they form a set - - extends the environment to bind them to new local names - - calls @rnMonoBinds@ to do the real work - -\begin{code} -rnBinds :: RdrNameHsBinds - -> (RenamedHsBinds -> RnMS (result, FreeVars)) - -> RnMS (result, FreeVars) - -rnBinds EmptyBinds thing_inside = thing_inside EmptyBinds -rnBinds (MonoBind bind sigs _) thing_inside = rnMonoBinds bind sigs thing_inside - -- the parser doesn't produce other forms - - -rnMonoBinds :: RdrNameMonoBinds - -> [RdrNameSig] - -> (RenamedHsBinds -> RnMS (result, FreeVars)) - -> RnMS (result, FreeVars) - -rnMonoBinds EmptyMonoBinds sigs thing_inside = thing_inside EmptyBinds - -rnMonoBinds mbinds sigs thing_inside -- Non-empty monobinds - = -- Extract all the binders in this group, - -- and extend current scope, inventing new names for the new binders - -- This also checks that the names form a set - bindLocatedLocalsRn (text "a binding group") mbinders_w_srclocs $ \ new_mbinders -> - let - binder_set = mkNameSet new_mbinders - - -- Weed out the fixity declarations that do not - -- apply to any of the binders in this group. - (sigs_for_me, fixes_not_for_me) = partition forLocalBind sigs - - forLocalBind (FixSig sig@(FixitySig name _ _ )) = - isJust (lookupFM binder_occ_fm (rdrNameOcc name)) - forLocalBind _ = True - - binder_occ_fm = listToFM [(nameOccName x,x) | x <- new_mbinders] - - in - -- Report the fixity declarations in this group that - -- don't refer to any of the group's binders. - -- - mapRn_ (unknownSigErr) fixes_not_for_me `thenRn_` - renameSigs False binder_set - (lookupSigOccRn binder_occ_fm) sigs_for_me `thenRn` \ (siglist, sig_fvs) -> - let - fixity_sigs = [(name,sig) | FixSig sig@(FixitySig name _ _) <- siglist ] - in - -- Install the fixity declarations that do apply here and go. - extendFixityEnv fixity_sigs ( - rn_mono_binds siglist mbinds - ) `thenRn` \ (binds, bind_fvs) -> - - -- Now do the "thing inside", and deal with the free-variable calculations - thing_inside binds `thenRn` \ (result,result_fvs) -> - let - all_fvs = result_fvs `plusFV` bind_fvs `plusFV` sig_fvs - unused_binders = nameSetToList (binder_set `minusNameSet` all_fvs) - in - warnUnusedLocalBinds unused_binders `thenRn_` - returnRn (result, delListFromNameSet all_fvs new_mbinders) - where - mbinders_w_srclocs = bagToList (collectMonoBinders mbinds) -\end{code} - - -%************************************************************************ -%* * -%* MonoBinds -- the main work is done here -%* * -%************************************************************************ - -@rn_mono_binds@ is used by *both* top-level and nested bindings. It -assumes that all variables bound in this group are already in scope. -This is done *either* by pass 3 (for the top-level bindings), *or* by -@rnMonoBinds@ (for the nested ones). - -\begin{code} -rn_mono_binds :: [RenamedSig] -- Signatures attached to this group - -> RdrNameMonoBinds - -> RnMS (RenamedHsBinds, -- - FreeVars) -- Free variables - -rn_mono_binds siglist mbinds - = - -- Rename the bindings, returning a MonoBindsInfo - -- which is a list of indivisible vertices so far as - -- the strongly-connected-components (SCC) analysis is concerned - flattenMonoBinds siglist mbinds `thenRn` \ mbinds_info -> - - -- Do the SCC analysis - let - edges = mkEdges (mbinds_info `zip` [(0::Int)..]) - scc_result = stronglyConnComp edges - final_binds = foldr1 ThenBinds (map reconstructCycle scc_result) - - -- Deal with bound and free-var calculation - rhs_fvs = plusFVs [fvs | (_,fvs,_,_) <- mbinds_info] - in - returnRn (final_binds, rhs_fvs) -\end{code} - -@flattenMonoBinds@ is ever-so-slightly magical in that it sticks -unique ``vertex tags'' on its output; minor plumbing required. - -Sigh - need to pass along the signatures for the group of bindings, -in case any of them - -\begin{code} -flattenMonoBinds :: [RenamedSig] -- Signatures - -> RdrNameMonoBinds - -> RnMS [FlatMonoBindsInfo] - -flattenMonoBinds sigs EmptyMonoBinds = returnRn [] - -flattenMonoBinds sigs (AndMonoBinds bs1 bs2) - = flattenMonoBinds sigs bs1 `thenRn` \ flat1 -> - flattenMonoBinds sigs bs2 `thenRn` \ flat2 -> - returnRn (flat1 ++ flat2) - -flattenMonoBinds sigs (PatMonoBind pat grhss locn) - = pushSrcLocRn locn $ - rnPat pat `thenRn` \ (pat', pat_fvs) -> - - -- Find which things are bound in this group - let - names_bound_here = mkNameSet (collectPatBinders pat') - sigs_for_me = sigsForMe (`elemNameSet` names_bound_here) sigs - in - rnGRHSs grhss `thenRn` \ (grhss', fvs) -> - returnRn - [(names_bound_here, - fvs `plusFV` pat_fvs, - PatMonoBind pat' grhss' locn, - sigs_for_me - )] - -flattenMonoBinds sigs (FunMonoBind name inf matches locn) - = pushSrcLocRn locn $ - lookupBndrRn name `thenRn` \ new_name -> - let - sigs_for_me = sigsForMe (new_name ==) sigs - in - mapFvRn rnMatch matches `thenRn` \ (new_matches, fvs) -> - mapRn_ (checkPrecMatch inf new_name) new_matches `thenRn_` - returnRn - [(unitNameSet new_name, - fvs, - FunMonoBind new_name inf new_matches locn, - sigs_for_me - )] -\end{code} - - -@rnMethodBinds@ is used for the method bindings of a class and an instance -declaration. like @rnMonoBinds@ but without dependency analysis. - -NOTA BENE: we record each *binder* of a method-bind group as a free variable. -That's crucial when dealing with an instance decl: - instance Foo (T a) where - op x = ... -This might be the *sole* occurrence of 'op' for an imported class Foo, -and unless op occurs we won't treat the type signature of op in the class -decl for Foo as a source of instance-decl gates. But we should! Indeed, -in many ways the op in an instance decl is just like an occurrence, not -a binder. - -\begin{code} -rnMethodBinds :: RdrNameMonoBinds -> RnMS (RenamedMonoBinds, FreeVars) - -rnMethodBinds EmptyMonoBinds = returnRn (EmptyMonoBinds, emptyFVs) - -rnMethodBinds (AndMonoBinds mb1 mb2) - = rnMethodBinds mb1 `thenRn` \ (mb1', fvs1) -> - rnMethodBinds mb2 `thenRn` \ (mb2', fvs2) -> - returnRn (mb1' `AndMonoBinds` mb2', fvs1 `plusFV` fvs2) - -rnMethodBinds (FunMonoBind name inf matches locn) - = pushSrcLocRn locn $ - - lookupGlobalOccRn name `thenRn` \ sel_name -> - -- We use the selector name as the binder - - mapFvRn rnMatch matches `thenRn` \ (new_matches, fvs) -> - mapRn_ (checkPrecMatch inf sel_name) new_matches `thenRn_` - returnRn (FunMonoBind sel_name inf new_matches locn, fvs `addOneFV` sel_name) - -rnMethodBinds (PatMonoBind (VarPatIn name) grhss locn) - = pushSrcLocRn locn $ - lookupGlobalOccRn name `thenRn` \ sel_name -> - rnGRHSs grhss `thenRn` \ (grhss', fvs) -> - returnRn (PatMonoBind (VarPatIn sel_name) grhss' locn, fvs `addOneFV` sel_name) - --- Can't handle method pattern-bindings which bind multiple methods. -rnMethodBinds mbind@(PatMonoBind other_pat _ locn) - = pushSrcLocRn locn $ - failWithRn (EmptyMonoBinds, emptyFVs) (methodBindErr mbind) -\end{code} - - -%************************************************************************ -%* * -\subsection[reconstruct-deps]{Reconstructing dependencies} -%* * -%************************************************************************ - -This @MonoBinds@- and @ClassDecls@-specific code is segregated here, -as the two cases are similar. - -\begin{code} -reconstructCycle :: SCC FlatMonoBindsInfo - -> RenamedHsBinds - -reconstructCycle (AcyclicSCC (_, _, binds, sigs)) - = MonoBind binds sigs NonRecursive - -reconstructCycle (CyclicSCC cycle) - = MonoBind this_gp_binds this_gp_sigs Recursive - where - this_gp_binds = foldr1 AndMonoBinds [binds | (_, _, binds, _) <- cycle] - this_gp_sigs = foldr1 (++) [sigs | (_, _, _, sigs) <- cycle] -\end{code} - -%************************************************************************ -%* * -%* Manipulating FlatMonoBindInfo * -%* * -%************************************************************************ - -During analysis a @MonoBinds@ is flattened to a @FlatMonoBindsInfo@. -The @RenamedMonoBinds@ is always an empty bind, a pattern binding or -a function binding, and has itself been dependency-analysed and -renamed. - -\begin{code} -type FlatMonoBindsInfo - = (NameSet, -- Set of names defined in this vertex - NameSet, -- Set of names used in this vertex - RenamedMonoBinds, - [RenamedSig]) -- Signatures, if any, for this vertex - -mkEdges :: [(FlatMonoBindsInfo, VertexTag)] -> [(FlatMonoBindsInfo, VertexTag, [VertexTag])] - -mkEdges flat_info - = [ (info, tag, dest_vertices (nameSetToList names_used)) - | (info@(names_defined, names_used, mbind, sigs), tag) <- flat_info - ] - where - -- An edge (v,v') indicates that v depends on v' - dest_vertices src_mentions = [ target_vertex - | ((names_defined, _, _, _), target_vertex) <- flat_info, - mentioned_name <- src_mentions, - mentioned_name `elemNameSet` names_defined - ] -\end{code} - - -%************************************************************************ -%* * -\subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)} -%* * -%************************************************************************ - -@renameSigs@ checks for: (a)~more than one sig for one thing; -(b)~signatures given for things not bound here; (c)~with suitably -flaggery, that all top-level things have type signatures. - -At the moment we don't gather free-var info from the types in -signatures. We'd only need this if we wanted to report unused tyvars. - -\begin{code} -renameSigs :: Bool -- True => warn if (required) type signatures are missing. - -> NameSet -- Set of names bound in this group - -> (RdrName -> RnMS Name) - -> [RdrNameSig] - -> RnMS ([RenamedSig], FreeVars) -- List of Sig constructors - -renameSigs sigs_required binders lookup_occ_nm sigs - = -- Rename the signatures - mapFvRn (renameSig lookup_occ_nm) sigs `thenRn` \ (sigs', fvs) -> - - -- Check for (a) duplicate signatures - -- (b) signatures for things not in this group - -- (c) optionally, bindings with no signature - let - (goodies, dups) = removeDups cmp_sig (sigsForMe (not . isUnboundName) sigs') - not_this_group = sigsForMe (not . (`elemNameSet` binders)) goodies - type_sig_vars = [n | Sig n _ _ <- goodies] - un_sigd_binders | sigs_required = nameSetToList binders `minusList` type_sig_vars - | otherwise = [] - in - mapRn_ dupSigDeclErr dups `thenRn_` - mapRn_ unknownSigErr not_this_group `thenRn_` - mapRn_ (addWarnRn.missingSigWarn) un_sigd_binders `thenRn_` - returnRn (sigs', fvs) - -- bad ones and all: - -- we need bindings of *some* sort for every name - --- We use lookupOccRn in the signatures, which is a little bit unsatisfactory --- because this won't work for: --- instance Foo T where --- {-# INLINE op #-} --- Baz.op = ... --- We'll just rename the INLINE prag to refer to whatever other 'op' --- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.) --- Doesn't seem worth much trouble to sort this. - -renameSig lookup_occ_nm (Sig v ty src_loc) - = pushSrcLocRn src_loc $ - lookup_occ_nm v `thenRn` \ new_v -> - rnHsSigType (quotes (ppr v)) ty `thenRn` \ (new_ty,fvs) -> - returnRn (Sig new_v new_ty src_loc, fvs `addOneFV` new_v) - -renameSig _ (SpecInstSig ty src_loc) - = pushSrcLocRn src_loc $ - rnHsSigType (text "A SPECIALISE instance pragma") ty `thenRn` \ (new_ty, fvs) -> - returnRn (SpecInstSig new_ty src_loc, fvs) - -renameSig lookup_occ_nm (SpecSig v ty src_loc) - = pushSrcLocRn src_loc $ - lookup_occ_nm v `thenRn` \ new_v -> - rnHsSigType (quotes (ppr v)) ty `thenRn` \ (new_ty,fvs) -> - returnRn (SpecSig new_v new_ty src_loc, fvs `addOneFV` new_v) - -renameSig lookup_occ_nm (InlineSig v src_loc) - = pushSrcLocRn src_loc $ - lookup_occ_nm v `thenRn` \ new_v -> - returnRn (InlineSig new_v src_loc, unitFV new_v) - -renameSig lookup_occ_nm (FixSig (FixitySig v fix src_loc)) - = pushSrcLocRn src_loc $ - lookup_occ_nm v `thenRn` \ new_v -> - returnRn (FixSig (FixitySig new_v fix src_loc), unitFV new_v) - -renameSig lookup_occ_nm (NoInlineSig v src_loc) - = pushSrcLocRn src_loc $ - lookup_occ_nm v `thenRn` \ new_v -> - returnRn (NoInlineSig new_v src_loc, unitFV new_v) -\end{code} - -Checking for distinct signatures; oh, so boring - -\begin{code} -cmp_sig :: RenamedSig -> RenamedSig -> Ordering -cmp_sig (Sig n1 _ _) (Sig n2 _ _) = n1 `compare` n2 -cmp_sig (InlineSig n1 _) (InlineSig n2 _) = n1 `compare` n2 -cmp_sig (NoInlineSig n1 _) (NoInlineSig n2 _) = n1 `compare` n2 -cmp_sig (SpecInstSig ty1 _) (SpecInstSig ty2 _) = cmpHsType compare ty1 ty2 -cmp_sig (SpecSig n1 ty1 _) (SpecSig n2 ty2 _) - = -- may have many specialisations for one value; - -- but not ones that are exactly the same... - thenCmp (n1 `compare` n2) (cmpHsType compare ty1 ty2) - -cmp_sig other_1 other_2 -- Tags *must* be different - | (sig_tag other_1) _LT_ (sig_tag other_2) = LT - | otherwise = GT - -sig_tag (Sig n1 _ _) = (ILIT(1) :: FAST_INT) -sig_tag (SpecSig n1 _ _) = ILIT(2) -sig_tag (InlineSig n1 _) = ILIT(3) -sig_tag (NoInlineSig n1 _) = ILIT(4) -sig_tag (SpecInstSig _ _) = ILIT(5) -sig_tag (FixSig _) = ILIT(6) -sig_tag _ = panic# "tag(RnBinds)" -\end{code} - -%************************************************************************ -%* * -\subsection{Error messages} -%* * -%************************************************************************ - -\begin{code} -dupSigDeclErr (sig:sigs) - = pushSrcLocRn loc $ - addErrRn (sep [ptext SLIT("Duplicate") <+> ptext what_it_is <> colon, - ppr sig]) - where - (what_it_is, loc) = sig_doc sig - -unknownSigErr sig - = pushSrcLocRn loc $ - addErrRn (sep [ptext SLIT("Misplaced"), - ptext what_it_is <> colon, - ppr sig]) - where - (what_it_is, loc) = sig_doc sig - -sig_doc (Sig _ _ loc) = (SLIT("type signature"),loc) -sig_doc (ClassOpSig _ _ _ loc) = (SLIT("class-method type signature"), loc) -sig_doc (SpecSig _ _ loc) = (SLIT("SPECIALISE pragma"),loc) -sig_doc (InlineSig _ loc) = (SLIT("INLINE pragma"),loc) -sig_doc (NoInlineSig _ loc) = (SLIT("NOINLINE pragma"),loc) -sig_doc (SpecInstSig _ loc) = (SLIT("SPECIALISE instance pragma"),loc) -sig_doc (FixSig (FixitySig _ _ loc)) = (SLIT("fixity declaration"), loc) - -missingSigWarn var - = sep [ptext SLIT("definition but no type signature for"), quotes (ppr var)] - -methodBindErr mbind - = hang (ptext SLIT("Can't handle multiple methods defined by one pattern binding")) - 4 (ppr mbind) -\end{code} +% +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 +% +\section[RnBinds]{Renaming and dependency analysis of bindings} + +This module does renaming and dependency analysis on value bindings in +the abstract syntax. It does {\em not} do cycle-checks on class or +type-synonym declarations; those cannot be done at this stage because +they may be affected by renaming (which isn't fully worked out yet). + +\begin{code} +module RnBinds ( + rnTopMonoBinds, rnMonoBinds, rnMethodBinds, + renameSigs, renameSigsFVs, unknownSigErr + ) where + +#include "HsVersions.h" + + +import HsSyn +import HsBinds ( eqHsSig, sigName, hsSigDoc ) +import RdrHsSyn +import RnHsSyn +import TcRnMonad +import RnTypes ( rnHsSigType, rnHsType ) +import RnExpr ( rnMatch, rnGRHSs, rnPat, checkPrecMatch ) +import RnEnv ( bindLocatedLocalsRn, lookupBndrRn, lookupInstDeclBndr, + lookupSigOccRn, bindPatSigTyVars, bindLocalFixities, + warnUnusedLocalBinds, mapFvRn, extendTyVarEnvFVRn, + ) +import CmdLineOpts ( DynFlag(..) ) +import Digraph ( stronglyConnComp, SCC(..) ) +import Name ( Name, nameOccName, nameSrcLoc ) +import NameSet +import RdrName ( RdrName, rdrNameOcc ) +import BasicTypes ( RecFlag(..), FixitySig(..) ) +import List ( partition ) +import Outputable +import PrelNames ( isUnboundName ) +\end{code} + +-- ToDo: Put the annotations into the monad, so that they arrive in the proper +-- place and can be used when complaining. + +The code tree received by the function @rnBinds@ contains definitions +in where-clauses which are all apparently mutually recursive, but which may +not really depend upon each other. For example, in the top level program +\begin{verbatim} +f x = y where a = x + y = x +\end{verbatim} +the definitions of @a@ and @y@ do not depend on each other at all. +Unfortunately, the typechecker cannot always check such definitions. +\footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive +definitions. In Proceedings of the International Symposium on Programming, +Toulouse, pp. 217-39. LNCS 167. Springer Verlag.} +However, the typechecker usually can check definitions in which only the +strongly connected components have been collected into recursive bindings. +This is precisely what the function @rnBinds@ does. + +ToDo: deal with case where a single monobinds binds the same variable +twice. + +The vertag tag is a unique @Int@; the tags only need to be unique +within one @MonoBinds@, so that unique-Int plumbing is done explicitly +(heavy monad machinery not needed). + +\begin{code} +type VertexTag = Int +\end{code} + +%************************************************************************ +%* * +%* naming conventions * +%* * +%************************************************************************ + +\subsection[name-conventions]{Name conventions} + +The basic algorithm involves walking over the tree and returning a tuple +containing the new tree plus its free variables. Some functions, such +as those walking polymorphic bindings (HsBinds) and qualifier lists in +list comprehensions (@Quals@), return the variables bound in local +environments. These are then used to calculate the free variables of the +expression evaluated in these environments. + +Conventions for variable names are as follows: +\begin{itemize} +\item +new code is given a prime to distinguish it from the old. + +\item +a set of variables defined in @Exp@ is written @dvExp@ + +\item +a set of variables free in @Exp@ is written @fvExp@ +\end{itemize} + +%************************************************************************ +%* * +%* analysing polymorphic bindings (HsBinds, Bind, MonoBinds) * +%* * +%************************************************************************ + +\subsubsection[dep-HsBinds]{Polymorphic bindings} + +Non-recursive expressions are reconstructed without any changes at top +level, although their component expressions may have to be altered. +However, non-recursive expressions are currently not expected as +\Haskell{} programs, and this code should not be executed. + +Monomorphic bindings contain information that is returned in a tuple +(a @FlatMonoBindsInfo@) containing: + +\begin{enumerate} +\item +a unique @Int@ that serves as the ``vertex tag'' for this binding. + +\item +the name of a function or the names in a pattern. These are a set +referred to as @dvLhs@, the defined variables of the left hand side. + +\item +the free variables of the body. These are referred to as @fvBody@. + +\item +the definition's actual code. This is referred to as just @code@. +\end{enumerate} + +The function @nonRecDvFv@ returns two sets of variables. The first is +the set of variables defined in the set of monomorphic bindings, while the +second is the set of free variables in those bindings. + +The set of variables defined in a non-recursive binding is just the +union of all of them, as @union@ removes duplicates. However, the +free variables in each successive set of cumulative bindings is the +union of those in the previous set plus those of the newest binding after +the defined variables of the previous set have been removed. + +@rnMethodBinds@ deals only with the declarations in class and +instance declarations. It expects only to see @FunMonoBind@s, and +it expects the global environment to contain bindings for the binders +(which are all class operations). + +%************************************************************************ +%* * +\subsubsection{ Top-level bindings} +%* * +%************************************************************************ + +@rnTopMonoBinds@ assumes that the environment already +contains bindings for the binders of this particular binding. + +\begin{code} +rnTopMonoBinds mbinds sigs + = mappM lookupBndrRn binder_rdr_names `thenM` \ binder_names -> + bindPatSigTyVars (collectSigTysFromMonoBinds mbinds) $ + let + bndr_name_set = mkNameSet binder_names + in + renameSigsFVs (okBindSig bndr_name_set) sigs `thenM` \ (siglist, sig_fvs) -> + + ifOptM Opt_WarnMissingSigs ( + let + type_sig_vars = [n | Sig n _ _ <- siglist] + un_sigd_binders = nameSetToList (delListFromNameSet bndr_name_set type_sig_vars) + in + mappM_ missingSigWarn un_sigd_binders + ) `thenM_` + + rn_mono_binds siglist mbinds `thenM` \ (final_binds, bind_fvs) -> + returnM (final_binds, bind_fvs `plusFV` sig_fvs) + where + binder_rdr_names = collectMonoBinders mbinds +\end{code} + +%************************************************************************ +%* * +%* Nested binds +%* * +%************************************************************************ + +\subsubsection{Nested binds} + +@rnMonoBinds@ +\begin{itemize} +\item collects up the binders for this declaration group, +\item checks that they form a set +\item extends the environment to bind them to new local names +\item calls @rnMonoBinds@ to do the real work +\end{itemize} +% +\begin{code} +rnMonoBinds :: RdrNameMonoBinds + -> [RdrNameSig] + -> (RenamedHsBinds -> RnM (result, FreeVars)) + -> RnM (result, FreeVars) + +rnMonoBinds mbinds sigs thing_inside -- Non-empty monobinds + = -- Extract all the binders in this group, + -- and extend current scope, inventing new names for the new binders + -- This also checks that the names form a set + bindLocatedLocalsRn doc mbinders_w_srclocs $ \ new_mbinders -> + bindPatSigTyVars (collectSigTysFromMonoBinds mbinds) $ + let + binder_set = mkNameSet new_mbinders + in + -- Rename the signatures + renameSigsFVs (okBindSig binder_set) sigs `thenM` \ (siglist, sig_fvs) -> + + -- Report the fixity declarations in this group that + -- don't refer to any of the group's binders. + -- Then install the fixity declarations that do apply here + -- Notice that they scope over thing_inside too + bindLocalFixities [sig | FixSig sig <- siglist ] $ + + rn_mono_binds siglist mbinds `thenM` \ (binds, bind_fvs) -> + + -- Now do the "thing inside", and deal with the free-variable calculations + thing_inside binds `thenM` \ (result,result_fvs) -> + let + all_fvs = result_fvs `plusFV` bind_fvs `plusFV` sig_fvs + unused_binders = nameSetToList (binder_set `minusNameSet` all_fvs) + in + warnUnusedLocalBinds unused_binders `thenM_` + returnM (result, delListFromNameSet all_fvs new_mbinders) + where + mbinders_w_srclocs = collectLocatedMonoBinders mbinds + doc = text "In the binding group for" <+> pp_bndrs mbinders_w_srclocs + pp_bndrs [(b,_)] = quotes (ppr b) + pp_bndrs bs = fsep (punctuate comma [ppr b | (b,_) <- bs]) +\end{code} + + +%************************************************************************ +%* * +\subsubsection{ MonoBinds -- the main work is done here} +%* * +%************************************************************************ + +@rn_mono_binds@ is used by {\em both} top-level and nested bindings. +It assumes that all variables bound in this group are already in scope. +This is done {\em either} by pass 3 (for the top-level bindings), +{\em or} by @rnMonoBinds@ (for the nested ones). + +\begin{code} +rn_mono_binds :: [RenamedSig] -- Signatures attached to this group + -> RdrNameMonoBinds + -> RnM (RenamedHsBinds, -- Dependency analysed + FreeVars) -- Free variables + +rn_mono_binds siglist mbinds + = + -- Rename the bindings, returning a MonoBindsInfo + -- which is a list of indivisible vertices so far as + -- the strongly-connected-components (SCC) analysis is concerned + flattenMonoBinds siglist mbinds `thenM` \ mbinds_info -> + + -- Do the SCC analysis + let + edges = mkEdges (mbinds_info `zip` [(0::Int)..]) + scc_result = stronglyConnComp edges + final_binds = foldr (ThenBinds . reconstructCycle) EmptyBinds scc_result + + -- Deal with bound and free-var calculation + rhs_fvs = plusFVs [fvs | (_,fvs,_,_) <- mbinds_info] + in + returnM (final_binds, rhs_fvs) +\end{code} + +@flattenMonoBinds@ is ever-so-slightly magical in that it sticks +unique ``vertex tags'' on its output; minor plumbing required. + +Sigh --- need to pass along the signatures for the group of bindings, +in case any of them \fbox{\ ???\ } + +\begin{code} +flattenMonoBinds :: [RenamedSig] -- Signatures + -> RdrNameMonoBinds + -> RnM [FlatMonoBindsInfo] + +flattenMonoBinds sigs EmptyMonoBinds = returnM [] + +flattenMonoBinds sigs (AndMonoBinds bs1 bs2) + = flattenMonoBinds sigs bs1 `thenM` \ flat1 -> + flattenMonoBinds sigs bs2 `thenM` \ flat2 -> + returnM (flat1 ++ flat2) + +flattenMonoBinds sigs (PatMonoBind pat grhss locn) + = addSrcLoc locn $ + rnPat pat `thenM` \ (pat', pat_fvs) -> + + -- Find which things are bound in this group + let + names_bound_here = mkNameSet (collectPatBinders pat') + in + sigsForMe names_bound_here sigs `thenM` \ sigs_for_me -> + rnGRHSs grhss `thenM` \ (grhss', fvs) -> + returnM + [(names_bound_here, + fvs `plusFV` pat_fvs, + PatMonoBind pat' grhss' locn, + sigs_for_me + )] + +flattenMonoBinds sigs (FunMonoBind name inf matches locn) + = addSrcLoc locn $ + lookupBndrRn name `thenM` \ new_name -> + let + names_bound_here = unitNameSet new_name + in + sigsForMe names_bound_here sigs `thenM` \ sigs_for_me -> + mapFvRn (rnMatch (FunRhs name)) matches `thenM` \ (new_matches, fvs) -> + mappM_ (checkPrecMatch inf new_name) new_matches `thenM_` + returnM + [(unitNameSet new_name, + fvs, + FunMonoBind new_name inf new_matches locn, + sigs_for_me + )] + + +sigsForMe names_bound_here sigs + = foldlM check [] (filter (sigForThisGroup names_bound_here) sigs) + where + check sigs sig = case filter (eqHsSig sig) sigs of + [] -> returnM (sig:sigs) + other -> dupSigDeclErr sig `thenM_` + returnM sigs +\end{code} + + +@rnMethodBinds@ is used for the method bindings of a class and an instance +declaration. Like @rnMonoBinds@ but without dependency analysis. + +NOTA BENE: we record each {\em binder} of a method-bind group as a free variable. +That's crucial when dealing with an instance decl: +\begin{verbatim} + instance Foo (T a) where + op x = ... +\end{verbatim} +This might be the {\em sole} occurrence of @op@ for an imported class @Foo@, +and unless @op@ occurs we won't treat the type signature of @op@ in the class +decl for @Foo@ as a source of instance-decl gates. But we should! Indeed, +in many ways the @op@ in an instance decl is just like an occurrence, not +a binder. + +\begin{code} +rnMethodBinds :: Name -- Class name + -> [Name] -- Names for generic type variables + -> RdrNameMonoBinds + -> RnM (RenamedMonoBinds, FreeVars) + +rnMethodBinds cls gen_tyvars EmptyMonoBinds = returnM (EmptyMonoBinds, emptyFVs) + +rnMethodBinds cls gen_tyvars (AndMonoBinds mb1 mb2) + = rnMethodBinds cls gen_tyvars mb1 `thenM` \ (mb1', fvs1) -> + rnMethodBinds cls gen_tyvars mb2 `thenM` \ (mb2', fvs2) -> + returnM (mb1' `AndMonoBinds` mb2', fvs1 `plusFV` fvs2) + +rnMethodBinds cls gen_tyvars (FunMonoBind name inf matches locn) + = addSrcLoc locn $ + + lookupInstDeclBndr cls name `thenM` \ sel_name -> + -- We use the selector name as the binder + + mapFvRn rn_match matches `thenM` \ (new_matches, fvs) -> + mappM_ (checkPrecMatch inf sel_name) new_matches `thenM_` + returnM (FunMonoBind sel_name inf new_matches locn, fvs `addOneFV` sel_name) + where + -- Gruesome; bring into scope the correct members of the generic type variables + -- See comments in RnSource.rnSourceDecl(ClassDecl) + rn_match match@(Match (TypePat ty : _) _ _) + = extendTyVarEnvFVRn gen_tvs (rnMatch (FunRhs name) match) + where + tvs = map rdrNameOcc (extractHsTyRdrNames ty) + gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs] + + rn_match match = rnMatch (FunRhs name) match + + +-- Can't handle method pattern-bindings which bind multiple methods. +rnMethodBinds cls gen_tyvars mbind@(PatMonoBind other_pat _ locn) + = addSrcLoc locn (addErr (methodBindErr mbind)) `thenM_` + returnM (EmptyMonoBinds, emptyFVs) +\end{code} + + +%************************************************************************ +%* * +\subsection[reconstruct-deps]{Reconstructing dependencies} +%* * +%************************************************************************ + +This @MonoBinds@- and @ClassDecls@-specific code is segregated here, +as the two cases are similar. + +\begin{code} +reconstructCycle :: SCC FlatMonoBindsInfo + -> RenamedHsBinds + +reconstructCycle (AcyclicSCC (_, _, binds, sigs)) + = MonoBind binds sigs NonRecursive + +reconstructCycle (CyclicSCC cycle) + = MonoBind this_gp_binds this_gp_sigs Recursive + where + this_gp_binds = foldr1 AndMonoBinds [binds | (_, _, binds, _) <- cycle] + this_gp_sigs = foldr1 (++) [sigs | (_, _, _, sigs) <- cycle] +\end{code} + +%************************************************************************ +%* * +\subsubsection{ Manipulating FlatMonoBindInfo} +%* * +%************************************************************************ + +During analysis a @MonoBinds@ is flattened to a @FlatMonoBindsInfo@. +The @RenamedMonoBinds@ is always an empty bind, a pattern binding or +a function binding, and has itself been dependency-analysed and +renamed. + +\begin{code} +type FlatMonoBindsInfo + = (NameSet, -- Set of names defined in this vertex + NameSet, -- Set of names used in this vertex + RenamedMonoBinds, + [RenamedSig]) -- Signatures, if any, for this vertex + +mkEdges :: [(FlatMonoBindsInfo, VertexTag)] -> [(FlatMonoBindsInfo, VertexTag, [VertexTag])] + +mkEdges flat_info + = [ (info, tag, dest_vertices (nameSetToList names_used)) + | (info@(names_defined, names_used, mbind, sigs), tag) <- flat_info + ] + where + -- An edge (v,v') indicates that v depends on v' + dest_vertices src_mentions = [ target_vertex + | ((names_defined, _, _, _), target_vertex) <- flat_info, + mentioned_name <- src_mentions, + mentioned_name `elemNameSet` names_defined + ] +\end{code} + + +%************************************************************************ +%* * +\subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)} +%* * +%************************************************************************ + +@renameSigs@ checks for: +\begin{enumerate} +\item more than one sig for one thing; +\item signatures given for things not bound here; +\item with suitably flaggery, that all top-level things have type signatures. +\end{enumerate} +% +At the moment we don't gather free-var info from the types in +signatures. We'd only need this if we wanted to report unused tyvars. + +\begin{code} +renameSigsFVs ok_sig sigs + = renameSigs ok_sig sigs `thenM` \ sigs' -> + returnM (sigs', hsSigsFVs sigs') + +renameSigs :: (RenamedSig -> Bool) -- OK-sig predicate + -> [RdrNameSig] + -> RnM [RenamedSig] + +renameSigs ok_sig [] = returnM [] + +renameSigs ok_sig sigs + = -- Rename the signatures + mappM renameSig sigs `thenM` \ sigs' -> + + -- Check for (a) duplicate signatures + -- (b) signatures for things not in this group + let + in_scope = filter is_in_scope sigs' + is_in_scope sig = case sigName sig of + Just n -> not (isUnboundName n) + Nothing -> True + (goods, bads) = partition ok_sig in_scope + in + mappM_ unknownSigErr bads `thenM_` + returnM goods + +-- We use lookupSigOccRn in the signatures, which is a little bit unsatisfactory +-- because this won't work for: +-- instance Foo T where +-- {-# INLINE op #-} +-- Baz.op = ... +-- We'll just rename the INLINE prag to refer to whatever other 'op' +-- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.) +-- Doesn't seem worth much trouble to sort this. + +renameSig :: Sig RdrName -> RnM (Sig Name) +-- ClassOpSig is renamed elsewhere. +renameSig (Sig v ty src_loc) + = addSrcLoc src_loc $ + lookupSigOccRn v `thenM` \ new_v -> + rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty -> + returnM (Sig new_v new_ty src_loc) + +renameSig (SpecInstSig ty src_loc) + = addSrcLoc src_loc $ + rnHsType (text "A SPECIALISE instance pragma") ty `thenM` \ new_ty -> + returnM (SpecInstSig new_ty src_loc) + +renameSig (SpecSig v ty src_loc) + = addSrcLoc src_loc $ + lookupSigOccRn v `thenM` \ new_v -> + rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty -> + returnM (SpecSig new_v new_ty src_loc) + +renameSig (FixSig (FixitySig v fix src_loc)) + = addSrcLoc src_loc $ + lookupSigOccRn v `thenM` \ new_v -> + returnM (FixSig (FixitySig new_v fix src_loc)) + +renameSig (InlineSig b v p src_loc) + = addSrcLoc src_loc $ + lookupSigOccRn v `thenM` \ new_v -> + returnM (InlineSig b new_v p src_loc) +\end{code} + + +%************************************************************************ +%* * +\subsection{Error messages} +%* * +%************************************************************************ + +\begin{code} +dupSigDeclErr sig + = addSrcLoc loc $ + addErr (sep [ptext SLIT("Duplicate") <+> what_it_is <> colon, + ppr sig]) + where + (what_it_is, loc) = hsSigDoc sig + +unknownSigErr sig + = addSrcLoc loc $ + addErr (sep [ptext SLIT("Misplaced") <+> what_it_is <> colon, + ppr sig]) + where + (what_it_is, loc) = hsSigDoc sig + +missingSigWarn var + = addSrcLoc (nameSrcLoc var) $ + addWarn (sep [ptext SLIT("Definition but no type signature for"), quotes (ppr var)]) + +methodBindErr mbind + = hang (ptext SLIT("Can't handle multiple methods defined by one pattern binding")) + 4 (ppr mbind) +\end{code}