ghc-lib-parser-0.20201101: compiler/GHC/Parser/PostProcess.hs
{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE ViewPatterns #-}
{-# OPTIONS_GHC -Wno-incomplete-record-updates #-}
--
-- (c) The University of Glasgow 2002-2006
--
-- Functions over HsSyn specialised to RdrName.
module GHC.Parser.PostProcess (
mkHsOpApp,
mkHsIntegral, mkHsFractional, mkHsIsString,
mkHsDo, mkSpliceDecl,
mkRoleAnnotDecl,
mkClassDecl,
mkTyData, mkDataFamInst,
mkTySynonym, mkTyFamInstEqn,
mkStandaloneKindSig,
mkTyFamInst,
mkFamDecl, mkLHsSigType,
mkInlinePragma,
mkPatSynMatchGroup,
mkRecConstrOrUpdate, -- HsExp -> [HsFieldUpdate] -> P HsExp
mkTyClD, mkInstD,
mkRdrRecordCon, mkRdrRecordUpd,
setRdrNameSpace,
fromSpecTyVarBndr, fromSpecTyVarBndrs,
cvBindGroup,
cvBindsAndSigs,
cvTopDecls,
placeHolderPunRhs,
-- Stuff to do with Foreign declarations
mkImport,
parseCImport,
mkExport,
mkExtName, -- RdrName -> CLabelString
mkGadtDecl, -- [Located RdrName] -> LHsType RdrName -> ConDecl RdrName
mkConDeclH98,
-- Bunch of functions in the parser monad for
-- checking and constructing values
checkImportDecl,
checkExpBlockArguments, checkCmdBlockArguments,
checkPrecP, -- Int -> P Int
checkContext, -- HsType -> P HsContext
checkPattern, -- HsExp -> P HsPat
checkPattern_hints,
checkMonadComp, -- P (HsStmtContext GhcPs)
checkValDef, -- (SrcLoc, HsExp, HsRhs, [HsDecl]) -> P HsDecl
checkValSigLhs,
LRuleTyTmVar, RuleTyTmVar(..),
mkRuleBndrs, mkRuleTyVarBndrs,
checkRuleTyVarBndrNames,
checkRecordSyntax,
checkEmptyGADTs,
addFatalError, hintBangPat,
mkBangTy,
UnpackednessPragma(..),
mkMultTy,
-- Help with processing exports
ImpExpSubSpec(..),
ImpExpQcSpec(..),
mkModuleImpExp,
mkTypeImpExp,
mkImpExpSubSpec,
checkImportSpec,
-- Token symbols
starSym,
-- Warnings and errors
warnStarIsType,
warnPrepositiveQualifiedModule,
failOpFewArgs,
failOpNotEnabledImportQualifiedPost,
failOpImportQualifiedTwice,
SumOrTuple (..),
-- Expression/command/pattern ambiguity resolution
PV,
runPV,
ECP(ECP, unECP),
DisambInfixOp(..),
DisambECP(..),
ecpFromExp,
ecpFromCmd,
PatBuilder,
-- Type/datacon ambiguity resolution
DisambTD(..),
addUnpackednessP,
dataConBuilderCon,
dataConBuilderDetails,
) where
import GHC.Prelude
import GHC.Hs -- Lots of it
import GHC.Core.TyCon ( TyCon, isTupleTyCon, tyConSingleDataCon_maybe )
import GHC.Core.DataCon ( DataCon, dataConTyCon )
import GHC.Core.ConLike ( ConLike(..) )
import GHC.Core.Coercion.Axiom ( Role, fsFromRole )
import GHC.Types.Name.Reader
import GHC.Types.Name
import GHC.Unit.Module (ModuleName)
import GHC.Types.Basic
import GHC.Types.Fixity
import GHC.Types.SourceText
import GHC.Parser.Types
import GHC.Parser.Lexer
import GHC.Parser.Errors
import GHC.Utils.Lexeme ( isLexCon )
import GHC.Types.TyThing
import GHC.Core.Type ( unrestrictedFunTyCon, Specificity(..) )
import GHC.Builtin.Types( cTupleTyConName, tupleTyCon, tupleDataCon,
nilDataConName, nilDataConKey,
listTyConName, listTyConKey, eqTyCon_RDR )
import GHC.Types.ForeignCall
import GHC.Types.SrcLoc
import GHC.Types.Unique ( hasKey )
import GHC.Data.OrdList
import GHC.Utils.Outputable as Outputable
import GHC.Data.FastString
import GHC.Data.Maybe
import GHC.Data.Bag
import GHC.Utils.Misc
import GHC.Parser.Annotation
import Data.List
import Data.Foldable
import GHC.Driver.Flags ( WarningFlag(..) )
import GHC.Utils.Panic
import Control.Monad
import Text.ParserCombinators.ReadP as ReadP
import Data.Char
import Data.Data ( dataTypeOf, fromConstr, dataTypeConstrs )
import Data.Kind ( Type )
#include "GhclibHsVersions.h"
{- **********************************************************************
Construction functions for Rdr stuff
********************************************************************* -}
-- | mkClassDecl builds a RdrClassDecl, filling in the names for tycon and
-- datacon by deriving them from the name of the class. We fill in the names
-- for the tycon and datacon corresponding to the class, by deriving them
-- from the name of the class itself. This saves recording the names in the
-- interface file (which would be equally good).
-- Similarly for mkConDecl, mkClassOpSig and default-method names.
-- *** See Note [The Naming story] in GHC.Hs.Decls ****
mkTyClD :: LTyClDecl (GhcPass p) -> LHsDecl (GhcPass p)
mkTyClD (L loc d) = L loc (TyClD noExtField d)
mkInstD :: LInstDecl (GhcPass p) -> LHsDecl (GhcPass p)
mkInstD (L loc d) = L loc (InstD noExtField d)
mkClassDecl :: SrcSpan
-> Located (Maybe (LHsContext GhcPs), LHsType GhcPs)
-> Located (a,[LHsFunDep GhcPs])
-> OrdList (LHsDecl GhcPs)
-> LayoutInfo
-> P (LTyClDecl GhcPs)
mkClassDecl loc (L _ (mcxt, tycl_hdr)) fds where_cls layoutInfo
= do { (binds, sigs, ats, at_defs, _, docs) <- cvBindsAndSigs where_cls
; let cxt = fromMaybe (noLoc []) mcxt
; (cls, tparams, fixity, ann) <- checkTyClHdr True tycl_hdr
; addAnnsAt loc ann -- Add any API Annotations to the top SrcSpan
; (tyvars,annst) <- checkTyVars (text "class") whereDots cls tparams
; addAnnsAt loc annst -- Add any API Annotations to the top SrcSpan
; return (L loc (ClassDecl { tcdCExt = layoutInfo
, tcdCtxt = cxt
, tcdLName = cls, tcdTyVars = tyvars
, tcdFixity = fixity
, tcdFDs = snd (unLoc fds)
, tcdSigs = mkClassOpSigs sigs
, tcdMeths = binds
, tcdATs = ats, tcdATDefs = at_defs
, tcdDocs = docs })) }
mkTyData :: SrcSpan
-> NewOrData
-> Maybe (Located CType)
-> Located (Maybe (LHsContext GhcPs), LHsType GhcPs)
-> Maybe (LHsKind GhcPs)
-> [LConDecl GhcPs]
-> HsDeriving GhcPs
-> P (LTyClDecl GhcPs)
mkTyData loc new_or_data cType (L _ (mcxt, tycl_hdr))
ksig data_cons maybe_deriv
= do { (tc, tparams, fixity, ann) <- checkTyClHdr False tycl_hdr
; addAnnsAt loc ann -- Add any API Annotations to the top SrcSpan
; (tyvars, anns) <- checkTyVars (ppr new_or_data) equalsDots tc tparams
; addAnnsAt loc anns -- Add any API Annotations to the top SrcSpan
; defn <- mkDataDefn new_or_data cType mcxt ksig data_cons maybe_deriv
; return (L loc (DataDecl { tcdDExt = noExtField,
tcdLName = tc, tcdTyVars = tyvars,
tcdFixity = fixity,
tcdDataDefn = defn })) }
mkDataDefn :: NewOrData
-> Maybe (Located CType)
-> Maybe (LHsContext GhcPs)
-> Maybe (LHsKind GhcPs)
-> [LConDecl GhcPs]
-> HsDeriving GhcPs
-> P (HsDataDefn GhcPs)
mkDataDefn new_or_data cType mcxt ksig data_cons maybe_deriv
= do { checkDatatypeContext mcxt
; let cxt = fromMaybe (noLoc []) mcxt
; return (HsDataDefn { dd_ext = noExtField
, dd_ND = new_or_data, dd_cType = cType
, dd_ctxt = cxt
, dd_cons = data_cons
, dd_kindSig = ksig
, dd_derivs = maybe_deriv }) }
mkTySynonym :: SrcSpan
-> LHsType GhcPs -- LHS
-> LHsType GhcPs -- RHS
-> P (LTyClDecl GhcPs)
mkTySynonym loc lhs rhs
= do { (tc, tparams, fixity, ann) <- checkTyClHdr False lhs
; addAnnsAt loc ann -- Add any API Annotations to the top SrcSpan
; (tyvars, anns) <- checkTyVars (text "type") equalsDots tc tparams
; addAnnsAt loc anns -- Add any API Annotations to the top SrcSpan
; return (L loc (SynDecl { tcdSExt = noExtField
, tcdLName = tc, tcdTyVars = tyvars
, tcdFixity = fixity
, tcdRhs = rhs })) }
mkStandaloneKindSig
:: SrcSpan
-> Located [Located RdrName] -- LHS
-> LHsKind GhcPs -- RHS
-> P (LStandaloneKindSig GhcPs)
mkStandaloneKindSig loc lhs rhs =
do { vs <- mapM check_lhs_name (unLoc lhs)
; v <- check_singular_lhs (reverse vs)
; return $ L loc $ StandaloneKindSig noExtField v (mkLHsSigType rhs) }
where
check_lhs_name v@(unLoc->name) =
if isUnqual name && isTcOcc (rdrNameOcc name)
then return v
else addFatalError $ Error (ErrUnexpectedQualifiedConstructor (unLoc v)) [] (getLoc v)
check_singular_lhs vs =
case vs of
[] -> panic "mkStandaloneKindSig: empty left-hand side"
[v] -> return v
_ -> addFatalError $ Error (ErrMultipleNamesInStandaloneKindSignature vs) [] (getLoc lhs)
mkTyFamInstEqn :: Maybe [LHsTyVarBndr () GhcPs]
-> LHsType GhcPs
-> LHsType GhcPs
-> P (TyFamInstEqn GhcPs,[AddAnn])
mkTyFamInstEqn bndrs lhs rhs
= do { (tc, tparams, fixity, ann) <- checkTyClHdr False lhs
; return (mkHsImplicitBndrs
(FamEqn { feqn_ext = noExtField
, feqn_tycon = tc
, feqn_bndrs = bndrs
, feqn_pats = tparams
, feqn_fixity = fixity
, feqn_rhs = rhs }),
ann) }
mkDataFamInst :: SrcSpan
-> NewOrData
-> Maybe (Located CType)
-> (Maybe ( LHsContext GhcPs), Maybe [LHsTyVarBndr () GhcPs]
, LHsType GhcPs)
-> Maybe (LHsKind GhcPs)
-> [LConDecl GhcPs]
-> HsDeriving GhcPs
-> P (LInstDecl GhcPs)
mkDataFamInst loc new_or_data cType (mcxt, bndrs, tycl_hdr)
ksig data_cons maybe_deriv
= do { (tc, tparams, fixity, ann) <- checkTyClHdr False tycl_hdr
; addAnnsAt loc ann -- Add any API Annotations to the top SrcSpan
; defn <- mkDataDefn new_or_data cType mcxt ksig data_cons maybe_deriv
; return (L loc (DataFamInstD noExtField (DataFamInstDecl (mkHsImplicitBndrs
(FamEqn { feqn_ext = noExtField
, feqn_tycon = tc
, feqn_bndrs = bndrs
, feqn_pats = tparams
, feqn_fixity = fixity
, feqn_rhs = defn }))))) }
mkTyFamInst :: SrcSpan
-> TyFamInstEqn GhcPs
-> P (LInstDecl GhcPs)
mkTyFamInst loc eqn
= return (L loc (TyFamInstD noExtField (TyFamInstDecl eqn)))
mkFamDecl :: SrcSpan
-> FamilyInfo GhcPs
-> LHsType GhcPs -- LHS
-> Located (FamilyResultSig GhcPs) -- Optional result signature
-> Maybe (LInjectivityAnn GhcPs) -- Injectivity annotation
-> P (LTyClDecl GhcPs)
mkFamDecl loc info lhs ksig injAnn
= do { (tc, tparams, fixity, ann) <- checkTyClHdr False lhs
; addAnnsAt loc ann -- Add any API Annotations to the top SrcSpan
; (tyvars, anns) <- checkTyVars (ppr info) equals_or_where tc tparams
; addAnnsAt loc anns -- Add any API Annotations to the top SrcSpan
; return (L loc (FamDecl noExtField (FamilyDecl
{ fdExt = noExtField
, fdInfo = info, fdLName = tc
, fdTyVars = tyvars
, fdFixity = fixity
, fdResultSig = ksig
, fdInjectivityAnn = injAnn }))) }
where
equals_or_where = case info of
DataFamily -> empty
OpenTypeFamily -> empty
ClosedTypeFamily {} -> whereDots
mkSpliceDecl :: LHsExpr GhcPs -> HsDecl GhcPs
-- If the user wrote
-- [pads| ... ] then return a QuasiQuoteD
-- $(e) then return a SpliceD
-- but if they wrote, say,
-- f x then behave as if they'd written $(f x)
-- ie a SpliceD
--
-- Typed splices are not allowed at the top level, thus we do not represent them
-- as spliced declaration. See #10945
mkSpliceDecl lexpr@(L loc expr)
| HsSpliceE _ splice@(HsUntypedSplice {}) <- expr
= SpliceD noExtField (SpliceDecl noExtField (L loc splice) ExplicitSplice)
| HsSpliceE _ splice@(HsQuasiQuote {}) <- expr
= SpliceD noExtField (SpliceDecl noExtField (L loc splice) ExplicitSplice)
| otherwise
= SpliceD noExtField (SpliceDecl noExtField (L loc (mkUntypedSplice BareSplice lexpr))
ImplicitSplice)
mkRoleAnnotDecl :: SrcSpan
-> Located RdrName -- type being annotated
-> [Located (Maybe FastString)] -- roles
-> P (LRoleAnnotDecl GhcPs)
mkRoleAnnotDecl loc tycon roles
= do { roles' <- mapM parse_role roles
; return $ L loc $ RoleAnnotDecl noExtField tycon roles' }
where
role_data_type = dataTypeOf (undefined :: Role)
all_roles = map fromConstr $ dataTypeConstrs role_data_type
possible_roles = [(fsFromRole role, role) | role <- all_roles]
parse_role (L loc_role Nothing) = return $ L loc_role Nothing
parse_role (L loc_role (Just role))
= case lookup role possible_roles of
Just found_role -> return $ L loc_role $ Just found_role
Nothing ->
let nearby = fuzzyLookup (unpackFS role)
(mapFst unpackFS possible_roles)
in
addFatalError $ Error (ErrIllegalRoleName role nearby) [] loc_role
-- | Converts a list of 'LHsTyVarBndr's annotated with their 'Specificity' to
-- binders without annotations. Only accepts specified variables, and errors if
-- any of the provided binders has an 'InferredSpec' annotation.
fromSpecTyVarBndrs :: [LHsTyVarBndr Specificity GhcPs] -> P [LHsTyVarBndr () GhcPs]
fromSpecTyVarBndrs = mapM fromSpecTyVarBndr
-- | Converts 'LHsTyVarBndr' annotated with its 'Specificity' to one without
-- annotations. Only accepts specified variables, and errors if the provided
-- binder has an 'InferredSpec' annotation.
fromSpecTyVarBndr :: LHsTyVarBndr Specificity GhcPs -> P (LHsTyVarBndr () GhcPs)
fromSpecTyVarBndr bndr = case bndr of
(L loc (UserTyVar xtv flag idp)) -> (check_spec flag loc)
>> return (L loc $ UserTyVar xtv () idp)
(L loc (KindedTyVar xtv flag idp k)) -> (check_spec flag loc)
>> return (L loc $ KindedTyVar xtv () idp k)
where
check_spec :: Specificity -> SrcSpan -> P ()
check_spec SpecifiedSpec _ = return ()
check_spec InferredSpec loc = addFatalError $ Error ErrInferredTypeVarNotAllowed [] loc
{- **********************************************************************
#cvBinds-etc# Converting to @HsBinds@, etc.
********************************************************************* -}
-- | Function definitions are restructured here. Each is assumed to be recursive
-- initially, and non recursive definitions are discovered by the dependency
-- analyser.
-- | Groups together bindings for a single function
cvTopDecls :: OrdList (LHsDecl GhcPs) -> [LHsDecl GhcPs]
cvTopDecls decls = getMonoBindAll (fromOL decls)
-- Declaration list may only contain value bindings and signatures.
cvBindGroup :: OrdList (LHsDecl GhcPs) -> P (HsValBinds GhcPs)
cvBindGroup binding
= do { (mbs, sigs, fam_ds, tfam_insts
, dfam_insts, _) <- cvBindsAndSigs binding
; ASSERT( null fam_ds && null tfam_insts && null dfam_insts)
return $ ValBinds noExtField mbs sigs }
cvBindsAndSigs :: OrdList (LHsDecl GhcPs)
-> P (LHsBinds GhcPs, [LSig GhcPs], [LFamilyDecl GhcPs]
, [LTyFamInstDecl GhcPs], [LDataFamInstDecl GhcPs], [LDocDecl])
-- Input decls contain just value bindings and signatures
-- and in case of class or instance declarations also
-- associated type declarations. They might also contain Haddock comments.
cvBindsAndSigs fb = do
fb' <- drop_bad_decls (fromOL fb)
return (partitionBindsAndSigs (getMonoBindAll fb'))
where
-- cvBindsAndSigs is called in several places in the parser,
-- and its items can be produced by various productions:
--
-- * decl (when parsing a where clause or a let-expression)
-- * decl_inst (when parsing an instance declaration)
-- * decl_cls (when parsing a class declaration)
--
-- partitionBindsAndSigs can handle almost all declaration forms produced
-- by the aforementioned productions, except for SpliceD, which we filter
-- out here (in drop_bad_decls).
--
-- We're not concerned with every declaration form possible, such as those
-- produced by the topdecl parser production, because cvBindsAndSigs is not
-- called on top-level declarations.
drop_bad_decls [] = return []
drop_bad_decls (L l (SpliceD _ d) : ds) = do
addError $ Error (ErrDeclSpliceNotAtTopLevel d) [] l
drop_bad_decls ds
drop_bad_decls (d:ds) = (d:) <$> drop_bad_decls ds
-----------------------------------------------------------------------------
-- Group function bindings into equation groups
getMonoBind :: LHsBind GhcPs -> [LHsDecl GhcPs]
-> (LHsBind GhcPs, [LHsDecl GhcPs])
-- Suppose (b',ds') = getMonoBind b ds
-- ds is a list of parsed bindings
-- b is a MonoBinds that has just been read off the front
-- Then b' is the result of grouping more equations from ds that
-- belong with b into a single MonoBinds, and ds' is the depleted
-- list of parsed bindings.
--
-- All Haddock comments between equations inside the group are
-- discarded.
--
-- No AndMonoBinds or EmptyMonoBinds here; just single equations
getMonoBind (L loc1 (FunBind { fun_id = fun_id1@(L _ f1)
, fun_matches =
MG { mg_alts = (L _ mtchs1) } }))
binds
| has_args mtchs1
= go mtchs1 loc1 binds []
where
go mtchs loc
((L loc2 (ValD _ (FunBind { fun_id = (L _ f2)
, fun_matches =
MG { mg_alts = (L _ mtchs2) } })))
: binds) _
| f1 == f2 = go (mtchs2 ++ mtchs)
(combineSrcSpans loc loc2) binds []
go mtchs loc (doc_decl@(L loc2 (DocD {})) : binds) doc_decls
= let doc_decls' = doc_decl : doc_decls
in go mtchs (combineSrcSpans loc loc2) binds doc_decls'
go mtchs loc binds doc_decls
= ( L loc (makeFunBind fun_id1 (reverse mtchs))
, (reverse doc_decls) ++ binds)
-- Reverse the final matches, to get it back in the right order
-- Do the same thing with the trailing doc comments
getMonoBind bind binds = (bind, binds)
-- Group together adjacent FunBinds for every function.
getMonoBindAll :: [LHsDecl GhcPs] -> [LHsDecl GhcPs]
getMonoBindAll [] = []
getMonoBindAll (L l (ValD _ b) : ds) =
let (L l' b', ds') = getMonoBind (L l b) ds
in L l' (ValD noExtField b') : getMonoBindAll ds'
getMonoBindAll (d : ds) = d : getMonoBindAll ds
has_args :: [LMatch GhcPs (LHsExpr GhcPs)] -> Bool
has_args [] = panic "GHC.Parser.PostProcess.has_args"
has_args (L _ (Match { m_pats = args }) : _) = not (null args)
-- Don't group together FunBinds if they have
-- no arguments. This is necessary now that variable bindings
-- with no arguments are now treated as FunBinds rather
-- than pattern bindings (tests/rename/should_fail/rnfail002).
{- **********************************************************************
#PrefixToHS-utils# Utilities for conversion
********************************************************************* -}
{- Note [Parsing data constructors is hard]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The problem with parsing data constructors is that they look a lot like types.
Compare:
(s1) data T = C t1 t2
(s2) type T = C t1 t2
Syntactically, there's little difference between these declarations, except in
(s1) 'C' is a data constructor, but in (s2) 'C' is a type constructor.
This similarity would pose no problem if we knew ahead of time if we are
parsing a type or a constructor declaration. Looking at (s1) and (s2), a simple
(but wrong!) rule comes to mind: in 'data' declarations assume we are parsing
data constructors, and in other contexts (e.g. 'type' declarations) assume we
are parsing type constructors.
This simple rule does not work because of two problematic cases:
(p1) data T = C t1 t2 :+ t3
(p2) data T = C t1 t2 => t3
In (p1) we encounter (:+) and it turns out we are parsing an infix data
declaration, so (C t1 t2) is a type and 'C' is a type constructor.
In (p2) we encounter (=>) and it turns out we are parsing an existential
context, so (C t1 t2) is a constraint and 'C' is a type constructor.
As the result, in order to determine whether (C t1 t2) declares a data
constructor, a type, or a context, we would need unlimited lookahead which
'happy' is not so happy with.
-}
-- | Reinterpret a type constructor, including type operators, as a data
-- constructor.
-- See Note [Parsing data constructors is hard]
tyConToDataCon :: SrcSpan -> RdrName -> Either Error (Located RdrName)
tyConToDataCon loc tc
| isTcOcc occ || isDataOcc occ
, isLexCon (occNameFS occ)
= return (L loc (setRdrNameSpace tc srcDataName))
| otherwise
= Left $ Error (ErrNotADataCon tc) [] loc
where
occ = rdrNameOcc tc
mkPatSynMatchGroup :: Located RdrName
-> Located (OrdList (LHsDecl GhcPs))
-> P (MatchGroup GhcPs (LHsExpr GhcPs))
mkPatSynMatchGroup (L loc patsyn_name) (L _ decls) =
do { matches <- mapM fromDecl (fromOL decls)
; when (null matches) (wrongNumberErr loc)
; return $ mkMatchGroup FromSource matches }
where
fromDecl (L loc decl@(ValD _ (PatBind _
pat@(L _ (ConPat NoExtField ln@(L _ name) details))
rhs _))) =
do { unless (name == patsyn_name) $
wrongNameBindingErr loc decl
; match <- case details of
PrefixCon pats -> return $ Match { m_ext = noExtField
, m_ctxt = ctxt, m_pats = pats
, m_grhss = rhs }
where
ctxt = FunRhs { mc_fun = ln
, mc_fixity = Prefix
, mc_strictness = NoSrcStrict }
InfixCon p1 p2 -> return $ Match { m_ext = noExtField
, m_ctxt = ctxt
, m_pats = [p1, p2]
, m_grhss = rhs }
where
ctxt = FunRhs { mc_fun = ln
, mc_fixity = Infix
, mc_strictness = NoSrcStrict }
RecCon{} -> recordPatSynErr loc pat
; return $ L loc match }
fromDecl (L loc decl) = extraDeclErr loc decl
extraDeclErr loc decl =
addFatalError $ Error (ErrNoSingleWhereBindInPatSynDecl patsyn_name decl) [] loc
wrongNameBindingErr loc decl =
addFatalError $ Error (ErrInvalidWhereBindInPatSynDecl patsyn_name decl) [] loc
wrongNumberErr loc =
addFatalError $ Error (ErrEmptyWhereInPatSynDecl patsyn_name) [] loc
recordPatSynErr :: SrcSpan -> LPat GhcPs -> P a
recordPatSynErr loc pat =
addFatalError $ Error (ErrRecordSyntaxInPatSynDecl pat) [] loc
mkConDeclH98 :: Located RdrName -> Maybe [LHsTyVarBndr Specificity GhcPs]
-> Maybe (LHsContext GhcPs) -> HsConDeclH98Details GhcPs
-> ConDecl GhcPs
mkConDeclH98 name mb_forall mb_cxt args
= ConDeclH98 { con_ext = noExtField
, con_name = name
, con_forall = noLoc $ isJust mb_forall
, con_ex_tvs = mb_forall `orElse` []
, con_mb_cxt = mb_cxt
, con_args = args
, con_doc = Nothing }
-- | Construct a GADT-style data constructor from the constructor names and
-- their type. Some interesting aspects of this function:
--
-- * This splits up the constructor type into its quantified type variables (if
-- provided), context (if provided), argument types, and result type, and
-- records whether this is a prefix or record GADT constructor. See
-- Note [GADT abstract syntax] in "GHC.Hs.Decls" for more details.
mkGadtDecl :: [Located RdrName]
-> LHsType GhcPs
-> P (ConDecl GhcPs, [AddAnn])
mkGadtDecl names ty = do
let (args, res_ty, anns)
| L _ (HsFunTy _ _w (L loc (HsRecTy _ rf)) res_ty) <- body_ty
= (RecConGADT (L loc rf), res_ty, [])
| otherwise
= let (arg_types, res_type, anns) = splitHsFunType body_ty
in (PrefixConGADT arg_types, res_type, anns)
pure ( ConDeclGADT { con_g_ext = noExtField
, con_names = names
, con_forall = L (getLoc ty) $ isJust mtvs
, con_qvars = fromMaybe [] mtvs
, con_mb_cxt = mcxt
, con_g_args = args
, con_res_ty = res_ty
, con_doc = Nothing }
, anns )
where
(mtvs, mcxt, body_ty) = splitLHsGadtTy ty
setRdrNameSpace :: RdrName -> NameSpace -> RdrName
-- ^ This rather gruesome function is used mainly by the parser.
-- When parsing:
--
-- > data T a = T | T1 Int
--
-- we parse the data constructors as /types/ because of parser ambiguities,
-- so then we need to change the /type constr/ to a /data constr/
--
-- The exact-name case /can/ occur when parsing:
--
-- > data [] a = [] | a : [a]
--
-- For the exact-name case we return an original name.
setRdrNameSpace (Unqual occ) ns = Unqual (setOccNameSpace ns occ)
setRdrNameSpace (Qual m occ) ns = Qual m (setOccNameSpace ns occ)
setRdrNameSpace (Orig m occ) ns = Orig m (setOccNameSpace ns occ)
setRdrNameSpace (Exact n) ns
| Just thing <- wiredInNameTyThing_maybe n
= setWiredInNameSpace thing ns
-- Preserve Exact Names for wired-in things,
-- notably tuples and lists
| isExternalName n
= Orig (nameModule n) occ
| otherwise -- This can happen when quoting and then
-- splicing a fixity declaration for a type
= Exact (mkSystemNameAt (nameUnique n) occ (nameSrcSpan n))
where
occ = setOccNameSpace ns (nameOccName n)
setWiredInNameSpace :: TyThing -> NameSpace -> RdrName
setWiredInNameSpace (ATyCon tc) ns
| isDataConNameSpace ns
= ty_con_data_con tc
| isTcClsNameSpace ns
= Exact (getName tc) -- No-op
setWiredInNameSpace (AConLike (RealDataCon dc)) ns
| isTcClsNameSpace ns
= data_con_ty_con dc
| isDataConNameSpace ns
= Exact (getName dc) -- No-op
setWiredInNameSpace thing ns
= pprPanic "setWiredinNameSpace" (pprNameSpace ns <+> ppr thing)
ty_con_data_con :: TyCon -> RdrName
ty_con_data_con tc
| isTupleTyCon tc
, Just dc <- tyConSingleDataCon_maybe tc
= Exact (getName dc)
| tc `hasKey` listTyConKey
= Exact nilDataConName
| otherwise -- See Note [setRdrNameSpace for wired-in names]
= Unqual (setOccNameSpace srcDataName (getOccName tc))
data_con_ty_con :: DataCon -> RdrName
data_con_ty_con dc
| let tc = dataConTyCon dc
, isTupleTyCon tc
= Exact (getName tc)
| dc `hasKey` nilDataConKey
= Exact listTyConName
| otherwise -- See Note [setRdrNameSpace for wired-in names]
= Unqual (setOccNameSpace tcClsName (getOccName dc))
{- Note [setRdrNameSpace for wired-in names]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In GHC.Types, which declares (:), we have
infixr 5 :
The ambiguity about which ":" is meant is resolved by parsing it as a
data constructor, but then using dataTcOccs to try the type constructor too;
and that in turn calls setRdrNameSpace to change the name-space of ":" to
tcClsName. There isn't a corresponding ":" type constructor, but it's painful
to make setRdrNameSpace partial, so we just make an Unqual name instead. It
really doesn't matter!
-}
eitherToP :: MonadP m => Either Error a -> m a
-- Adapts the Either monad to the P monad
eitherToP (Left err) = addFatalError err
eitherToP (Right thing) = return thing
checkTyVars :: SDoc -> SDoc -> Located RdrName -> [LHsTypeArg GhcPs]
-> P ( LHsQTyVars GhcPs -- the synthesized type variables
, [AddAnn] ) -- action which adds annotations
-- ^ Check whether the given list of type parameters are all type variables
-- (possibly with a kind signature).
checkTyVars pp_what equals_or_where tc tparms
= do { (tvs, anns) <- fmap unzip $ mapM check tparms
; return (mkHsQTvs tvs, concat anns) }
where
check (HsTypeArg _ ki@(L loc _)) = addFatalError $ Error (ErrUnexpectedTypeAppInDecl ki pp_what (unLoc tc)) [] loc
check (HsValArg ty) = chkParens [] ty
check (HsArgPar sp) = addFatalError $ Error (ErrMalformedDecl pp_what (unLoc tc)) [] sp
-- Keep around an action for adjusting the annotations of extra parens
chkParens :: [AddAnn] -> LHsType GhcPs
-> P (LHsTyVarBndr () GhcPs, [AddAnn])
chkParens acc (L l (HsParTy _ ty)) = chkParens (mkParensApiAnn l ++ acc) ty
chkParens acc ty = do
tv <- chk ty
return (tv, reverse acc)
-- Check that the name space is correct!
chk :: LHsType GhcPs -> P (LHsTyVarBndr () GhcPs)
chk (L l (HsKindSig _ (L lv (HsTyVar _ _ (L _ tv))) k))
| isRdrTyVar tv = return (L l (KindedTyVar noExtField () (L lv tv) k))
chk (L l (HsTyVar _ _ (L ltv tv)))
| isRdrTyVar tv = return (L l (UserTyVar noExtField () (L ltv tv)))
chk t@(L loc _)
= addFatalError $ Error (ErrUnexpectedTypeInDecl t pp_what (unLoc tc) tparms equals_or_where) [] loc
whereDots, equalsDots :: SDoc
-- Second argument to checkTyVars
whereDots = text "where ..."
equalsDots = text "= ..."
checkDatatypeContext :: Maybe (LHsContext GhcPs) -> P ()
checkDatatypeContext Nothing = return ()
checkDatatypeContext (Just c)
= do allowed <- getBit DatatypeContextsBit
unless allowed $ addError $ Error (ErrIllegalDataTypeContext c) [] (getLoc c)
type LRuleTyTmVar = Located RuleTyTmVar
data RuleTyTmVar = RuleTyTmVar (Located RdrName) (Maybe (LHsType GhcPs))
-- ^ Essentially a wrapper for a @RuleBndr GhcPs@
-- turns RuleTyTmVars into RuleBnrs - this is straightforward
mkRuleBndrs :: [LRuleTyTmVar] -> [LRuleBndr GhcPs]
mkRuleBndrs = fmap (fmap cvt_one)
where cvt_one (RuleTyTmVar v Nothing) = RuleBndr noExtField v
cvt_one (RuleTyTmVar v (Just sig)) =
RuleBndrSig noExtField v (mkHsPatSigType sig)
-- turns RuleTyTmVars into HsTyVarBndrs - this is more interesting
mkRuleTyVarBndrs :: [LRuleTyTmVar] -> [LHsTyVarBndr () GhcPs]
mkRuleTyVarBndrs = fmap (fmap cvt_one)
where cvt_one (RuleTyTmVar v Nothing)
= UserTyVar noExtField () (fmap tm_to_ty v)
cvt_one (RuleTyTmVar v (Just sig))
= KindedTyVar noExtField () (fmap tm_to_ty v) sig
-- takes something in namespace 'varName' to something in namespace 'tvName'
tm_to_ty (Unqual occ) = Unqual (setOccNameSpace tvName occ)
tm_to_ty _ = panic "mkRuleTyVarBndrs"
-- See note [Parsing explicit foralls in Rules] in Parser.y
checkRuleTyVarBndrNames :: [LHsTyVarBndr flag GhcPs] -> P ()
checkRuleTyVarBndrNames = mapM_ (check . fmap hsTyVarName)
where check (L loc (Unqual occ)) =
-- TODO: don't use string here, OccName has a Unique/FastString
when ((occNameString occ ==) `any` ["forall","family","role"])
(addFatalError $ Error (ErrParseErrorOnInput occ) [] loc)
check _ = panic "checkRuleTyVarBndrNames"
checkRecordSyntax :: (MonadP m, Outputable a) => Located a -> m (Located a)
checkRecordSyntax lr@(L loc r)
= do allowed <- getBit TraditionalRecordSyntaxBit
unless allowed $ addError $ Error (ErrIllegalTraditionalRecordSyntax (ppr r)) [] loc
return lr
-- | Check if the gadt_constrlist is empty. Only raise parse error for
-- `data T where` to avoid affecting existing error message, see #8258.
checkEmptyGADTs :: Located ([AddAnn], [LConDecl GhcPs])
-> P (Located ([AddAnn], [LConDecl GhcPs]))
checkEmptyGADTs gadts@(L span (_, [])) -- Empty GADT declaration.
= do gadtSyntax <- getBit GadtSyntaxBit -- GADTs implies GADTSyntax
unless gadtSyntax $ addError $ Error ErrIllegalWhereInDataDecl [] span
return gadts
checkEmptyGADTs gadts = return gadts -- Ordinary GADT declaration.
checkTyClHdr :: Bool -- True <=> class header
-- False <=> type header
-> LHsType GhcPs
-> P (Located RdrName, -- the head symbol (type or class name)
[LHsTypeArg GhcPs], -- parameters of head symbol
LexicalFixity, -- the declaration is in infix format
[AddAnn]) -- API Annotation for HsParTy when stripping parens
-- Well-formedness check and decomposition of type and class heads.
-- Decomposes T ty1 .. tyn into (T, [ty1, ..., tyn])
-- Int :*: Bool into (:*:, [Int, Bool])
-- returning the pieces
checkTyClHdr is_cls ty
= goL ty [] [] Prefix
where
goL (L l ty) acc ann fix = go l ty acc ann fix
-- workaround to define '*' despite StarIsType
go lp (HsParTy _ (L l (HsStarTy _ isUni))) acc ann fix
= do { addWarning Opt_WarnStarBinder (WarnStarBinder l)
; let name = mkOccName tcClsName (starSym isUni)
; return (L l (Unqual name), acc, fix, (ann ++ mkParensApiAnn lp)) }
go _ (HsTyVar _ _ ltc@(L _ tc)) acc ann fix
| isRdrTc tc = return (ltc, acc, fix, ann)
go _ (HsOpTy _ t1 ltc@(L _ tc) t2) acc ann _fix
| isRdrTc tc = return (ltc, HsValArg t1:HsValArg t2:acc, Infix, ann)
go l (HsParTy _ ty) acc ann fix = goL ty acc (ann ++mkParensApiAnn l) fix
go _ (HsAppTy _ t1 t2) acc ann fix = goL t1 (HsValArg t2:acc) ann fix
go _ (HsAppKindTy l ty ki) acc ann fix = goL ty (HsTypeArg l ki:acc) ann fix
go l (HsTupleTy _ HsBoxedOrConstraintTuple ts) [] ann fix
= return (L l (nameRdrName tup_name), map HsValArg ts, fix, ann)
where
arity = length ts
tup_name | is_cls = cTupleTyConName arity
| otherwise = getName (tupleTyCon Boxed arity)
-- See Note [Unit tuples] in GHC.Hs.Type (TODO: is this still relevant?)
go l _ _ _ _
= addFatalError $ Error (ErrMalformedTyOrClDecl ty) [] l
-- | Yield a parse error if we have a function applied directly to a do block
-- etc. and BlockArguments is not enabled.
checkExpBlockArguments :: LHsExpr GhcPs -> PV ()
checkCmdBlockArguments :: LHsCmd GhcPs -> PV ()
(checkExpBlockArguments, checkCmdBlockArguments) = (checkExpr, checkCmd)
where
checkExpr :: LHsExpr GhcPs -> PV ()
checkExpr expr = case unLoc expr of
HsDo _ (DoExpr m) _ -> check (ErrDoInFunAppExpr m) expr
HsDo _ (MDoExpr m) _ -> check (ErrMDoInFunAppExpr m) expr
HsLam {} -> check ErrLambdaInFunAppExpr expr
HsCase {} -> check ErrCaseInFunAppExpr expr
HsLamCase {} -> check ErrLambdaCaseInFunAppExpr expr
HsLet {} -> check ErrLetInFunAppExpr expr
HsIf {} -> check ErrIfInFunAppExpr expr
HsProc {} -> check ErrProcInFunAppExpr expr
_ -> return ()
checkCmd :: LHsCmd GhcPs -> PV ()
checkCmd cmd = case unLoc cmd of
HsCmdLam {} -> check ErrLambdaCmdInFunAppCmd cmd
HsCmdCase {} -> check ErrCaseCmdInFunAppCmd cmd
HsCmdIf {} -> check ErrIfCmdInFunAppCmd cmd
HsCmdLet {} -> check ErrLetCmdInFunAppCmd cmd
HsCmdDo {} -> check ErrDoCmdInFunAppCmd cmd
_ -> return ()
check err a = do
blockArguments <- getBit BlockArgumentsBit
unless blockArguments $
addError $ Error (err a) [] (getLoc a)
-- | Validate the context constraints and break up a context into a list
-- of predicates.
--
-- @
-- (Eq a, Ord b) --> [Eq a, Ord b]
-- Eq a --> [Eq a]
-- (Eq a) --> [Eq a]
-- (((Eq a))) --> [Eq a]
-- @
checkContext :: LHsType GhcPs -> P ([AddAnn],LHsContext GhcPs)
checkContext (L l orig_t)
= check [] (L l orig_t)
where
check anns (L lp (HsTupleTy _ HsBoxedOrConstraintTuple ts))
-- (Eq a, Ord b) shows up as a tuple type. Only boxed tuples can
-- be used as context constraints.
= return (anns ++ mkParensApiAnn lp,L l ts) -- Ditto ()
check anns (L lp1 (HsParTy _ ty))
-- to be sure HsParTy doesn't get into the way
= check anns' ty
where anns' = if l == lp1 then anns
else (anns ++ mkParensApiAnn lp1)
-- no need for anns, returning original
check _anns _t = return ([],L l [L l orig_t])
checkImportDecl :: Maybe (Located Token)
-> Maybe (Located Token)
-> P ()
checkImportDecl mPre mPost = do
let whenJust mg f = maybe (pure ()) f mg
importQualifiedPostEnabled <- getBit ImportQualifiedPostBit
-- Error if 'qualified' found in postpositive position and
-- 'ImportQualifiedPost' is not in effect.
whenJust mPost $ \post ->
when (not importQualifiedPostEnabled) $
failOpNotEnabledImportQualifiedPost (getLoc post)
-- Error if 'qualified' occurs in both pre and postpositive
-- positions.
whenJust mPost $ \post ->
when (isJust mPre) $
failOpImportQualifiedTwice (getLoc post)
-- Warn if 'qualified' found in prepositive position and
-- 'Opt_WarnPrepositiveQualifiedModule' is enabled.
whenJust mPre $ \pre ->
warnPrepositiveQualifiedModule (getLoc pre)
-- -------------------------------------------------------------------------
-- Checking Patterns.
-- We parse patterns as expressions and check for valid patterns below,
-- converting the expression into a pattern at the same time.
checkPattern :: Located (PatBuilder GhcPs) -> P (LPat GhcPs)
checkPattern = runPV . checkLPat
checkPattern_hints :: [Hint] -> PV (Located (PatBuilder GhcPs)) -> P (LPat GhcPs)
checkPattern_hints hints pp = runPV_hints hints (pp >>= checkLPat)
checkLPat :: Located (PatBuilder GhcPs) -> PV (LPat GhcPs)
checkLPat e@(L l _) = checkPat l e []
checkPat :: SrcSpan -> Located (PatBuilder GhcPs) -> [LPat GhcPs]
-> PV (LPat GhcPs)
checkPat loc (L l e@(PatBuilderVar (L _ c))) args
| isRdrDataCon c = return . L loc $ ConPat
{ pat_con_ext = noExtField
, pat_con = L l c
, pat_args = PrefixCon args
}
| not (null args) && patIsRec c =
add_hint SuggestRecursiveDo $
patFail l (ppr e)
checkPat loc (L _ (PatBuilderApp f e)) args
= do p <- checkLPat e
checkPat loc f (p : args)
checkPat loc (L _ e) []
= do p <- checkAPat loc e
return (L loc p)
checkPat loc e _
= patFail loc (ppr e)
checkAPat :: SrcSpan -> PatBuilder GhcPs -> PV (Pat GhcPs)
checkAPat loc e0 = do
nPlusKPatterns <- getBit NPlusKPatternsBit
case e0 of
PatBuilderPat p -> return p
PatBuilderVar x -> return (VarPat noExtField x)
-- Overloaded numeric patterns (e.g. f 0 x = x)
-- Negation is recorded separately, so that the literal is zero or +ve
-- NB. Negative *primitive* literals are already handled by the lexer
PatBuilderOverLit pos_lit -> return (mkNPat (L loc pos_lit) Nothing)
-- n+k patterns
PatBuilderOpApp
(L nloc (PatBuilderVar (L _ n)))
(L _ plus)
(L lloc (PatBuilderOverLit lit@(OverLit {ol_val = HsIntegral {}})))
| nPlusKPatterns && (plus == plus_RDR)
-> return (mkNPlusKPat (L nloc n) (L lloc lit))
-- Improve error messages for the @-operator when the user meant an @-pattern
PatBuilderOpApp _ op _ | opIsAt (unLoc op) -> do
addError $ Error ErrAtInPatPos [] (getLoc op)
return (WildPat noExtField)
PatBuilderOpApp l (L cl c) r
| isRdrDataCon c -> do
l <- checkLPat l
r <- checkLPat r
return $ ConPat
{ pat_con_ext = noExtField
, pat_con = L cl c
, pat_args = InfixCon l r
}
PatBuilderPar e -> checkLPat e >>= (return . (ParPat noExtField))
_ -> patFail loc (ppr e0)
placeHolderPunRhs :: DisambECP b => PV (Located b)
-- The RHS of a punned record field will be filled in by the renamer
-- It's better not to make it an error, in case we want to print it when
-- debugging
placeHolderPunRhs = mkHsVarPV (noLoc pun_RDR)
plus_RDR, pun_RDR :: RdrName
plus_RDR = mkUnqual varName (fsLit "+") -- Hack
pun_RDR = mkUnqual varName (fsLit "pun-right-hand-side")
checkPatField :: LHsRecField GhcPs (Located (PatBuilder GhcPs))
-> PV (LHsRecField GhcPs (LPat GhcPs))
checkPatField (L l fld) = do p <- checkLPat (hsRecFieldArg fld)
return (L l (fld { hsRecFieldArg = p }))
patFail :: SrcSpan -> SDoc -> PV a
patFail loc e = addFatalError $ Error (ErrParseErrorInPat e) [] loc
patIsRec :: RdrName -> Bool
patIsRec e = e == mkUnqual varName (fsLit "rec")
---------------------------------------------------------------------------
-- Check Equation Syntax
checkValDef :: Located (PatBuilder GhcPs)
-> Maybe (LHsType GhcPs)
-> Located (a,GRHSs GhcPs (LHsExpr GhcPs))
-> P ([AddAnn],HsBind GhcPs)
checkValDef lhs (Just sig) grhss
-- x :: ty = rhs parses as a *pattern* binding
= do lhs' <- runPV $ mkHsTySigPV (combineLocs lhs sig) lhs sig >>= checkLPat
checkPatBind lhs' grhss
checkValDef lhs Nothing g@(L l (_,grhss))
= do { mb_fun <- isFunLhs lhs
; case mb_fun of
Just (fun, is_infix, pats, ann) ->
checkFunBind NoSrcStrict ann (getLoc lhs)
fun is_infix pats (L l grhss)
Nothing -> do
lhs' <- checkPattern lhs
checkPatBind lhs' g }
checkFunBind :: SrcStrictness
-> [AddAnn]
-> SrcSpan
-> Located RdrName
-> LexicalFixity
-> [Located (PatBuilder GhcPs)]
-> Located (GRHSs GhcPs (LHsExpr GhcPs))
-> P ([AddAnn],HsBind GhcPs)
checkFunBind strictness ann lhs_loc fun is_infix pats (L rhs_span grhss)
= do ps <- runPV_hints param_hints (mapM checkLPat pats)
let match_span = combineSrcSpans lhs_loc rhs_span
-- Add back the annotations stripped from any HsPar values in the lhs
-- mapM_ (\a -> a match_span) ann
return (ann, makeFunBind fun
[L match_span (Match { m_ext = noExtField
, m_ctxt = FunRhs
{ mc_fun = fun
, mc_fixity = is_infix
, mc_strictness = strictness }
, m_pats = ps
, m_grhss = grhss })])
-- The span of the match covers the entire equation.
-- That isn't quite right, but it'll do for now.
where
param_hints
| Infix <- is_infix = [SuggestInfixBindMaybeAtPat (unLoc fun)]
| otherwise = []
makeFunBind :: Located RdrName -> [LMatch GhcPs (LHsExpr GhcPs)]
-> HsBind GhcPs
-- Like GHC.Hs.Utils.mkFunBind, but we need to be able to set the fixity too
makeFunBind fn ms
= FunBind { fun_ext = noExtField,
fun_id = fn,
fun_matches = mkMatchGroup FromSource ms,
fun_tick = [] }
-- See Note [FunBind vs PatBind]
checkPatBind :: LPat GhcPs
-> Located (a,GRHSs GhcPs (LHsExpr GhcPs))
-> P ([AddAnn],HsBind GhcPs)
checkPatBind lhs (L rhs_span (_,grhss))
| BangPat _ p <- unLoc lhs
, VarPat _ v <- unLoc p
= return ([], makeFunBind v [L match_span (m v)])
where
match_span = combineSrcSpans (getLoc lhs) rhs_span
m v = Match { m_ext = noExtField
, m_ctxt = FunRhs { mc_fun = v
, mc_fixity = Prefix
, mc_strictness = SrcStrict }
, m_pats = []
, m_grhss = grhss }
checkPatBind lhs (L _ (_,grhss))
= return ([],PatBind noExtField lhs grhss ([],[]))
checkValSigLhs :: LHsExpr GhcPs -> P (Located RdrName)
checkValSigLhs (L _ (HsVar _ lrdr@(L _ v)))
| isUnqual v
, not (isDataOcc (rdrNameOcc v))
= return lrdr
checkValSigLhs lhs@(L l _)
= addFatalError $ Error (ErrInvalidTypeSignature lhs) [] l
checkDoAndIfThenElse
:: (Outputable a, Outputable b, Outputable c)
=> (a -> Bool -> b -> Bool -> c -> ErrorDesc)
-> Located a -> Bool -> Located b -> Bool -> Located c -> PV ()
checkDoAndIfThenElse err guardExpr semiThen thenExpr semiElse elseExpr
| semiThen || semiElse = do
doAndIfThenElse <- getBit DoAndIfThenElseBit
let e = err (unLoc guardExpr)
semiThen (unLoc thenExpr)
semiElse (unLoc elseExpr)
loc = combineLocs guardExpr elseExpr
unless doAndIfThenElse $ addError (Error e [] loc)
| otherwise = return ()
isFunLhs :: Located (PatBuilder GhcPs)
-> P (Maybe (Located RdrName, LexicalFixity, [Located (PatBuilder GhcPs)],[AddAnn]))
-- A variable binding is parsed as a FunBind.
-- Just (fun, is_infix, arg_pats) if e is a function LHS
isFunLhs e = go e [] []
where
go (L loc (PatBuilderVar (L _ f))) es ann
| not (isRdrDataCon f) = return (Just (L loc f, Prefix, es, ann))
go (L _ (PatBuilderApp f e)) es ann = go f (e:es) ann
go (L l (PatBuilderPar e)) es@(_:_) ann = go e es (ann ++ mkParensApiAnn l)
go (L loc (PatBuilderOpApp l (L loc' op) r)) es ann
| not (isRdrDataCon op) -- We have found the function!
= return (Just (L loc' op, Infix, (l:r:es), ann))
| otherwise -- Infix data con; keep going
= do { mb_l <- go l es ann
; case mb_l of
Just (op', Infix, j : k : es', ann')
-> return (Just (op', Infix, j : op_app : es', ann'))
where
op_app = L loc (PatBuilderOpApp k
(L loc' op) r)
_ -> return Nothing }
go _ _ _ = return Nothing
mkBangTy :: SrcStrictness -> LHsType GhcPs -> HsType GhcPs
mkBangTy strictness =
HsBangTy noExtField (HsSrcBang NoSourceText NoSrcUnpack strictness)
-- | Result of parsing @{-\# UNPACK \#-}@ or @{-\# NOUNPACK \#-}@.
data UnpackednessPragma =
UnpackednessPragma [AddAnn] SourceText SrcUnpackedness
-- | Annotate a type with either an @{-\# UNPACK \#-}@ or a @{-\# NOUNPACK \#-}@ pragma.
addUnpackednessP :: MonadP m => Located UnpackednessPragma -> LHsType GhcPs -> m (LHsType GhcPs)
addUnpackednessP (L lprag (UnpackednessPragma anns prag unpk)) ty = do
let l' = combineSrcSpans lprag (getLoc ty)
t' = addUnpackedness ty
addAnnsAt l' anns
return (L l' t')
where
-- If we have a HsBangTy that only has a strictness annotation,
-- such as ~T or !T, then add the pragma to the existing HsBangTy.
--
-- Otherwise, wrap the type in a new HsBangTy constructor.
addUnpackedness (L _ (HsBangTy x bang t))
| HsSrcBang NoSourceText NoSrcUnpack strictness <- bang
= HsBangTy x (HsSrcBang prag unpk strictness) t
addUnpackedness t
= HsBangTy noExtField (HsSrcBang prag unpk NoSrcStrict) t
---------------------------------------------------------------------------
-- | Check for monad comprehensions
--
-- If the flag MonadComprehensions is set, return a 'MonadComp' context,
-- otherwise use the usual 'ListComp' context
checkMonadComp :: PV (HsStmtContext GhcRn)
checkMonadComp = do
monadComprehensions <- getBit MonadComprehensionsBit
return $ if monadComprehensions
then MonadComp
else ListComp
-- -------------------------------------------------------------------------
-- Expression/command/pattern ambiguity.
-- See Note [Ambiguous syntactic categories]
--
-- See Note [Ambiguous syntactic categories]
--
-- This newtype is required to avoid impredicative types in monadic
-- productions. That is, in a production that looks like
--
-- | ... {% return (ECP ...) }
--
-- we are dealing with
-- P ECP
-- whereas without a newtype we would be dealing with
-- P (forall b. DisambECP b => PV (Located b))
--
newtype ECP =
ECP { unECP :: forall b. DisambECP b => PV (Located b) }
ecpFromExp :: LHsExpr GhcPs -> ECP
ecpFromExp a = ECP (ecpFromExp' a)
ecpFromCmd :: LHsCmd GhcPs -> ECP
ecpFromCmd a = ECP (ecpFromCmd' a)
-- | Disambiguate infix operators.
-- See Note [Ambiguous syntactic categories]
class DisambInfixOp b where
mkHsVarOpPV :: Located RdrName -> PV (Located b)
mkHsConOpPV :: Located RdrName -> PV (Located b)
mkHsInfixHolePV :: SrcSpan -> PV (Located b)
instance DisambInfixOp (HsExpr GhcPs) where
mkHsVarOpPV v = return $ L (getLoc v) (HsVar noExtField v)
mkHsConOpPV v = return $ L (getLoc v) (HsVar noExtField v)
mkHsInfixHolePV l = return $ L l hsHoleExpr
instance DisambInfixOp RdrName where
mkHsConOpPV (L l v) = return $ L l v
mkHsVarOpPV (L l v) = return $ L l v
mkHsInfixHolePV l = addFatalError $ Error ErrInvalidInfixHole [] l
-- | Disambiguate constructs that may appear when we do not know ahead of time whether we are
-- parsing an expression, a command, or a pattern.
-- See Note [Ambiguous syntactic categories]
class b ~ (Body b) GhcPs => DisambECP b where
-- | See Note [Body in DisambECP]
type Body b :: Type -> Type
-- | Return a command without ambiguity, or fail in a non-command context.
ecpFromCmd' :: LHsCmd GhcPs -> PV (Located b)
-- | Return an expression without ambiguity, or fail in a non-expression context.
ecpFromExp' :: LHsExpr GhcPs -> PV (Located b)
-- | Disambiguate "\... -> ..." (lambda)
mkHsLamPV :: SrcSpan -> MatchGroup GhcPs (Located b) -> PV (Located b)
-- | Disambiguate "let ... in ..."
mkHsLetPV :: SrcSpan -> LHsLocalBinds GhcPs -> Located b -> PV (Located b)
-- | Infix operator representation
type InfixOp b
-- | Bring superclass constraints on InfixOp into scope.
-- See Note [UndecidableSuperClasses for associated types]
superInfixOp :: (DisambInfixOp (InfixOp b) => PV (Located b )) -> PV (Located b)
-- | Disambiguate "f # x" (infix operator)
mkHsOpAppPV :: SrcSpan -> Located b -> Located (InfixOp b) -> Located b -> PV (Located b)
-- | Disambiguate "case ... of ..."
mkHsCasePV :: SrcSpan -> LHsExpr GhcPs -> MatchGroup GhcPs (Located b) -> PV (Located b)
-- | Disambiguate @\\case ...@ (lambda case)
mkHsLamCasePV :: SrcSpan -> MatchGroup GhcPs (Located b) -> PV (Located b)
-- | Function argument representation
type FunArg b
-- | Bring superclass constraints on FunArg into scope.
-- See Note [UndecidableSuperClasses for associated types]
superFunArg :: (DisambECP (FunArg b) => PV (Located b)) -> PV (Located b)
-- | Disambiguate "f x" (function application)
mkHsAppPV :: SrcSpan -> Located b -> Located (FunArg b) -> PV (Located b)
-- | Disambiguate "f @t" (visible type application)
mkHsAppTypePV :: SrcSpan -> Located b -> LHsType GhcPs -> PV (Located b)
-- | Disambiguate "if ... then ... else ..."
mkHsIfPV :: SrcSpan
-> LHsExpr GhcPs
-> Bool -- semicolon?
-> Located b
-> Bool -- semicolon?
-> Located b
-> PV (Located b)
-- | Disambiguate "do { ... }" (do notation)
mkHsDoPV ::
SrcSpan ->
Maybe ModuleName ->
Located [LStmt GhcPs (Located b)] ->
PV (Located b)
-- | Disambiguate "( ... )" (parentheses)
mkHsParPV :: SrcSpan -> Located b -> PV (Located b)
-- | Disambiguate a variable "f" or a data constructor "MkF".
mkHsVarPV :: Located RdrName -> PV (Located b)
-- | Disambiguate a monomorphic literal
mkHsLitPV :: Located (HsLit GhcPs) -> PV (Located b)
-- | Disambiguate an overloaded literal
mkHsOverLitPV :: Located (HsOverLit GhcPs) -> PV (Located b)
-- | Disambiguate a wildcard
mkHsWildCardPV :: SrcSpan -> PV (Located b)
-- | Disambiguate "a :: t" (type annotation)
mkHsTySigPV :: SrcSpan -> Located b -> LHsType GhcPs -> PV (Located b)
-- | Disambiguate "[a,b,c]" (list syntax)
mkHsExplicitListPV :: SrcSpan -> [Located b] -> PV (Located b)
-- | Disambiguate "$(...)" and "[quasi|...|]" (TH splices)
mkHsSplicePV :: Located (HsSplice GhcPs) -> PV (Located b)
-- | Disambiguate "f { a = b, ... }" syntax (record construction and record updates)
mkHsRecordPV ::
SrcSpan ->
SrcSpan ->
Located b ->
([LHsRecField GhcPs (Located b)], Maybe SrcSpan) ->
PV (Located b)
-- | Disambiguate "-a" (negation)
mkHsNegAppPV :: SrcSpan -> Located b -> PV (Located b)
-- | Disambiguate "(# a)" (right operator section)
mkHsSectionR_PV :: SrcSpan -> Located (InfixOp b) -> Located b -> PV (Located b)
-- | Disambiguate "(a -> b)" (view pattern)
mkHsViewPatPV :: SrcSpan -> LHsExpr GhcPs -> Located b -> PV (Located b)
-- | Disambiguate "a@b" (as-pattern)
mkHsAsPatPV :: SrcSpan -> Located RdrName -> Located b -> PV (Located b)
-- | Disambiguate "~a" (lazy pattern)
mkHsLazyPatPV :: SrcSpan -> Located b -> PV (Located b)
-- | Disambiguate "!a" (bang pattern)
mkHsBangPatPV :: SrcSpan -> Located b -> PV (Located b)
-- | Disambiguate tuple sections and unboxed sums
mkSumOrTuplePV :: SrcSpan -> Boxity -> SumOrTuple b -> PV (Located b)
-- | Validate infixexp LHS to reject unwanted {-# SCC ... #-} pragmas
rejectPragmaPV :: Located b -> PV ()
{- Note [UndecidableSuperClasses for associated types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(This Note is about the code in GHC, not about the user code that we are parsing)
Assume we have a class C with an associated type T:
class C a where
type T a
...
If we want to add 'C (T a)' as a superclass, we need -XUndecidableSuperClasses:
{-# LANGUAGE UndecidableSuperClasses #-}
class C (T a) => C a where
type T a
...
Unfortunately, -XUndecidableSuperClasses don't work all that well, sometimes
making GHC loop. The workaround is to bring this constraint into scope
manually with a helper method:
class C a where
type T a
superT :: (C (T a) => r) -> r
In order to avoid ambiguous types, 'r' must mention 'a'.
For consistency, we use this approach for all constraints on associated types,
even when -XUndecidableSuperClasses are not required.
-}
{- Note [Body in DisambECP]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are helper functions (mkBodyStmt, mkBindStmt, unguardedRHS, etc) that
require their argument to take a form of (body GhcPs) for some (body :: Type ->
*). To satisfy this requirement, we say that (b ~ Body b GhcPs) in the
superclass constraints of DisambECP.
The alternative is to change mkBodyStmt, mkBindStmt, unguardedRHS, etc, to drop
this requirement. It is possible and would allow removing the type index of
PatBuilder, but leads to worse type inference, breaking some code in the
typechecker.
-}
instance DisambECP (HsCmd GhcPs) where
type Body (HsCmd GhcPs) = HsCmd
ecpFromCmd' = return
ecpFromExp' (L l e) = cmdFail l (ppr e)
mkHsLamPV l mg = return $ L l (HsCmdLam noExtField mg)
mkHsLetPV l bs e = return $ L l (HsCmdLet noExtField bs e)
type InfixOp (HsCmd GhcPs) = HsExpr GhcPs
superInfixOp m = m
mkHsOpAppPV l c1 op c2 = do
let cmdArg c = L (getLoc c) $ HsCmdTop noExtField c
return $ L l $ HsCmdArrForm noExtField op Infix Nothing [cmdArg c1, cmdArg c2]
mkHsCasePV l c mg = return $ L l (HsCmdCase noExtField c mg)
mkHsLamCasePV l mg = return $ L l (HsCmdLamCase noExtField mg)
type FunArg (HsCmd GhcPs) = HsExpr GhcPs
superFunArg m = m
mkHsAppPV l c e = do
checkCmdBlockArguments c
checkExpBlockArguments e
return $ L l (HsCmdApp noExtField c e)
mkHsAppTypePV l c t = cmdFail l (ppr c <+> text "@" <> ppr t)
mkHsIfPV l c semi1 a semi2 b = do
checkDoAndIfThenElse ErrSemiColonsInCondCmd c semi1 a semi2 b
return $ L l (mkHsCmdIf c a b)
mkHsDoPV l Nothing stmts = return $ L l (HsCmdDo noExtField stmts)
mkHsDoPV l (Just m) _ = addFatalError $ Error (ErrQualifiedDoInCmd m) [] l
mkHsParPV l c = return $ L l (HsCmdPar noExtField c)
mkHsVarPV (L l v) = cmdFail l (ppr v)
mkHsLitPV (L l a) = cmdFail l (ppr a)
mkHsOverLitPV (L l a) = cmdFail l (ppr a)
mkHsWildCardPV l = cmdFail l (text "_")
mkHsTySigPV l a sig = cmdFail l (ppr a <+> text "::" <+> ppr sig)
mkHsExplicitListPV l xs = cmdFail l $
brackets (fsep (punctuate comma (map ppr xs)))
mkHsSplicePV (L l sp) = cmdFail l (ppr sp)
mkHsRecordPV l _ a (fbinds, ddLoc) = cmdFail l $
ppr a <+> ppr (mk_rec_fields fbinds ddLoc)
mkHsNegAppPV l a = cmdFail l (text "-" <> ppr a)
mkHsSectionR_PV l op c = cmdFail l $
let pp_op = fromMaybe (panic "cannot print infix operator")
(ppr_infix_expr (unLoc op))
in pp_op <> ppr c
mkHsViewPatPV l a b = cmdFail l $
ppr a <+> text "->" <+> ppr b
mkHsAsPatPV l v c = cmdFail l $
pprPrefixOcc (unLoc v) <> text "@" <> ppr c
mkHsLazyPatPV l c = cmdFail l $
text "~" <> ppr c
mkHsBangPatPV l c = cmdFail l $
text "!" <> ppr c
mkSumOrTuplePV l boxity a = cmdFail l (pprSumOrTuple boxity a)
rejectPragmaPV _ = return ()
cmdFail :: SrcSpan -> SDoc -> PV a
cmdFail loc e = addFatalError $ Error (ErrParseErrorInCmd e) [] loc
instance DisambECP (HsExpr GhcPs) where
type Body (HsExpr GhcPs) = HsExpr
ecpFromCmd' (L l c) = do
addError $ Error (ErrArrowCmdInExpr c) [] l
return (L l hsHoleExpr)
ecpFromExp' = return
mkHsLamPV l mg = return $ L l (HsLam noExtField mg)
mkHsLetPV l bs c = return $ L l (HsLet noExtField bs c)
type InfixOp (HsExpr GhcPs) = HsExpr GhcPs
superInfixOp m = m
mkHsOpAppPV l e1 op e2 =
return $ L l $ OpApp noExtField e1 op e2
mkHsCasePV l e mg = return $ L l (HsCase noExtField e mg)
mkHsLamCasePV l mg = return $ L l (HsLamCase noExtField mg)
type FunArg (HsExpr GhcPs) = HsExpr GhcPs
superFunArg m = m
mkHsAppPV l e1 e2 = do
checkExpBlockArguments e1
checkExpBlockArguments e2
return $ L l (HsApp noExtField e1 e2)
mkHsAppTypePV l e t = do
checkExpBlockArguments e
return $ L l (HsAppType noExtField e (mkHsWildCardBndrs t))
mkHsIfPV l c semi1 a semi2 b = do
checkDoAndIfThenElse ErrSemiColonsInCondExpr c semi1 a semi2 b
return $ L l (mkHsIf c a b)
mkHsDoPV l mod stmts = return $ L l (HsDo noExtField (DoExpr mod) stmts)
mkHsParPV l e = return $ L l (HsPar noExtField e)
mkHsVarPV v@(getLoc -> l) = return $ L l (HsVar noExtField v)
mkHsLitPV (L l a) = return $ L l (HsLit noExtField a)
mkHsOverLitPV (L l a) = return $ L l (HsOverLit noExtField a)
mkHsWildCardPV l = return $ L l hsHoleExpr
mkHsTySigPV l a sig = return $ L l (ExprWithTySig noExtField a (mkLHsSigWcType sig))
mkHsExplicitListPV l xs = return $ L l (ExplicitList noExtField Nothing xs)
mkHsSplicePV sp = return $ mapLoc (HsSpliceE noExtField) sp
mkHsRecordPV l lrec a (fbinds, ddLoc) = do
r <- mkRecConstrOrUpdate a lrec (fbinds, ddLoc)
checkRecordSyntax (L l r)
mkHsNegAppPV l a = return $ L l (NegApp noExtField a noSyntaxExpr)
mkHsSectionR_PV l op e = return $ L l (SectionR noExtField op e)
mkHsViewPatPV l a b = addError (Error (ErrViewPatInExpr a b) [] l)
>> return (L l hsHoleExpr)
mkHsAsPatPV l v e = addError (Error (ErrTypeAppWithoutSpace (unLoc v) e) [] l)
>> return (L l hsHoleExpr)
mkHsLazyPatPV l e = addError (Error (ErrLazyPatWithoutSpace e) [] l)
>> return (L l hsHoleExpr)
mkHsBangPatPV l e = addError (Error (ErrBangPatWithoutSpace e) [] l)
>> return (L l hsHoleExpr)
mkSumOrTuplePV = mkSumOrTupleExpr
rejectPragmaPV (L _ (OpApp _ _ _ e)) =
-- assuming left-associative parsing of operators
rejectPragmaPV e
rejectPragmaPV (L l (HsPragE _ prag _)) = addError $ Error (ErrUnallowedPragma prag) [] l
rejectPragmaPV _ = return ()
hsHoleExpr :: HsExpr GhcPs
hsHoleExpr = HsUnboundVar noExtField (mkVarOcc "_")
instance DisambECP (PatBuilder GhcPs) where
type Body (PatBuilder GhcPs) = PatBuilder
ecpFromCmd' (L l c) = addFatalError $ Error (ErrArrowCmdInPat c) [] l
ecpFromExp' (L l e) = addFatalError $ Error (ErrArrowExprInPat e) [] l
mkHsLamPV l _ = addFatalError $ Error ErrLambdaInPat [] l
mkHsLetPV l _ _ = addFatalError $ Error ErrLetInPat [] l
type InfixOp (PatBuilder GhcPs) = RdrName
superInfixOp m = m
mkHsOpAppPV l p1 op p2 = return $ L l $ PatBuilderOpApp p1 op p2
mkHsCasePV l _ _ = addFatalError $ Error ErrCaseInPat [] l
mkHsLamCasePV l _ = addFatalError $ Error ErrLambdaCaseInPat [] l
type FunArg (PatBuilder GhcPs) = PatBuilder GhcPs
superFunArg m = m
mkHsAppPV l p1 p2 = return $ L l (PatBuilderApp p1 p2)
mkHsAppTypePV l _ _ = addFatalError $ Error ErrTypeAppInPat [] l
mkHsIfPV l _ _ _ _ _ = addFatalError $ Error ErrIfTheElseInPat [] l
mkHsDoPV l _ _ = addFatalError $ Error ErrDoNotationInPat [] l
mkHsParPV l p = return $ L l (PatBuilderPar p)
mkHsVarPV v@(getLoc -> l) = return $ L l (PatBuilderVar v)
mkHsLitPV lit@(L l a) = do
checkUnboxedStringLitPat lit
return $ L l (PatBuilderPat (LitPat noExtField a))
mkHsOverLitPV (L l a) = return $ L l (PatBuilderOverLit a)
mkHsWildCardPV l = return $ L l (PatBuilderPat (WildPat noExtField))
mkHsTySigPV l b sig = do
p <- checkLPat b
return $ L l (PatBuilderPat (SigPat noExtField p (mkHsPatSigType sig)))
mkHsExplicitListPV l xs = do
ps <- traverse checkLPat xs
return (L l (PatBuilderPat (ListPat noExtField ps)))
mkHsSplicePV (L l sp) = return $ L l (PatBuilderPat (SplicePat noExtField sp))
mkHsRecordPV l _ a (fbinds, ddLoc) = do
r <- mkPatRec a (mk_rec_fields fbinds ddLoc)
checkRecordSyntax (L l r)
mkHsNegAppPV l (L lp p) = do
lit <- case p of
PatBuilderOverLit pos_lit -> return (L lp pos_lit)
_ -> patFail l (text "-" <> ppr p)
return $ L l (PatBuilderPat (mkNPat lit (Just noSyntaxExpr)))
mkHsSectionR_PV l op p = patFail l (pprInfixOcc (unLoc op) <> ppr p)
mkHsViewPatPV l a b = do
p <- checkLPat b
return $ L l (PatBuilderPat (ViewPat noExtField a p))
mkHsAsPatPV l v e = do
p <- checkLPat e
return $ L l (PatBuilderPat (AsPat noExtField v p))
mkHsLazyPatPV l e = do
p <- checkLPat e
return $ L l (PatBuilderPat (LazyPat noExtField p))
mkHsBangPatPV l e = do
p <- checkLPat e
let pb = BangPat noExtField p
hintBangPat l pb
return $ L l (PatBuilderPat pb)
mkSumOrTuplePV = mkSumOrTuplePat
rejectPragmaPV _ = return ()
checkUnboxedStringLitPat :: Located (HsLit GhcPs) -> PV ()
checkUnboxedStringLitPat (L loc lit) =
case lit of
HsStringPrim _ _ -- Trac #13260
-> addFatalError $ Error (ErrIllegalUnboxedStringInPat lit) [] loc
_ -> return ()
mkPatRec ::
Located (PatBuilder GhcPs) ->
HsRecFields GhcPs (Located (PatBuilder GhcPs)) ->
PV (PatBuilder GhcPs)
mkPatRec (unLoc -> PatBuilderVar c) (HsRecFields fs dd)
| isRdrDataCon (unLoc c)
= do fs <- mapM checkPatField fs
return $ PatBuilderPat $ ConPat
{ pat_con_ext = noExtField
, pat_con = c
, pat_args = RecCon (HsRecFields fs dd)
}
mkPatRec p _ =
addFatalError $ Error (ErrInvalidRecordCon (unLoc p)) [] (getLoc p)
-- | Disambiguate constructs that may appear when we do not know
-- ahead of time whether we are parsing a type or a newtype/data constructor.
--
-- See Note [Ambiguous syntactic categories] for the general idea.
--
-- See Note [Parsing data constructors is hard] for the specific issue this
-- particular class is solving.
--
class DisambTD b where
-- | Process the head of a type-level function/constructor application,
-- i.e. the @H@ in @H a b c@.
mkHsAppTyHeadPV :: LHsType GhcPs -> PV (Located b)
-- | Disambiguate @f x@ (function application or prefix data constructor).
mkHsAppTyPV :: Located b -> LHsType GhcPs -> PV (Located b)
-- | Disambiguate @f \@t@ (visible kind application)
mkHsAppKindTyPV :: Located b -> SrcSpan -> LHsType GhcPs -> PV (Located b)
-- | Disambiguate @f \# x@ (infix operator)
mkHsOpTyPV :: LHsType GhcPs -> Located RdrName -> LHsType GhcPs -> PV (Located b)
-- | Disambiguate @{-\# UNPACK \#-} t@ (unpack/nounpack pragma)
mkUnpackednessPV :: Located UnpackednessPragma -> Located b -> PV (Located b)
instance DisambTD (HsType GhcPs) where
mkHsAppTyHeadPV = return
mkHsAppTyPV t1 t2 = return (mkHsAppTy t1 t2)
mkHsAppKindTyPV t l_at ki = return (mkHsAppKindTy l' t ki)
where l' = combineSrcSpans l_at (getLoc ki)
mkHsOpTyPV t1 op t2 = return (mkLHsOpTy t1 op t2)
mkUnpackednessPV = addUnpackednessP
dataConBuilderCon :: DataConBuilder -> Located RdrName
dataConBuilderCon (PrefixDataConBuilder _ dc) = dc
dataConBuilderCon (InfixDataConBuilder _ dc _) = dc
dataConBuilderDetails :: DataConBuilder -> HsConDeclH98Details GhcPs
-- Detect when the record syntax is used:
-- data T = MkT { ... }
dataConBuilderDetails (PrefixDataConBuilder flds _)
| [L l_t (HsRecTy _ fields)] <- toList flds
= RecCon (L l_t fields)
-- Normal prefix constructor, e.g. data T = MkT A B C
dataConBuilderDetails (PrefixDataConBuilder flds _)
= PrefixCon (map hsLinear (toList flds))
-- Infix constructor, e.g. data T = Int :! Bool
dataConBuilderDetails (InfixDataConBuilder lhs _ rhs)
= InfixCon (hsLinear lhs) (hsLinear rhs)
instance DisambTD DataConBuilder where
mkHsAppTyHeadPV = tyToDataConBuilder
mkHsAppTyPV (L l (PrefixDataConBuilder flds fn)) t =
return $
L (combineSrcSpans l (getLoc t))
(PrefixDataConBuilder (flds `snocOL` t) fn)
mkHsAppTyPV (L _ InfixDataConBuilder{}) _ =
-- This case is impossible because of the way
-- the grammar in Parser.y is written (see infixtype/ftype).
panic "mkHsAppTyPV: InfixDataConBuilder"
mkHsAppKindTyPV lhs l_at ki =
addFatalError $ Error (ErrUnexpectedKindAppInDataCon (unLoc lhs) (unLoc ki)) [] l_at
mkHsOpTyPV lhs (L l_tc tc) rhs = do
check_no_ops (unLoc rhs) -- check the RHS because parsing type operators is right-associative
data_con <- eitherToP $ tyConToDataCon l_tc tc
return $ L l (InfixDataConBuilder lhs data_con rhs)
where
l = combineLocs lhs rhs
check_no_ops (HsBangTy _ _ t) = check_no_ops (unLoc t)
check_no_ops (HsOpTy{}) =
addError $ Error (ErrInvalidInfixDataCon (unLoc lhs) tc (unLoc rhs)) [] l
check_no_ops _ = return ()
mkUnpackednessPV unpk constr_stuff
| L _ (InfixDataConBuilder lhs data_con rhs) <- constr_stuff
= -- When the user writes data T = {-# UNPACK #-} Int :+ Bool
-- we apply {-# UNPACK #-} to the LHS
do lhs' <- addUnpackednessP unpk lhs
let l = combineLocs unpk constr_stuff
return $ L l (InfixDataConBuilder lhs' data_con rhs)
| otherwise =
do addError $ Error ErrUnpackDataCon [] (getLoc unpk)
return constr_stuff
tyToDataConBuilder :: LHsType GhcPs -> PV (Located DataConBuilder)
tyToDataConBuilder (L l (HsTyVar _ NotPromoted (L _ v))) = do
data_con <- eitherToP $ tyConToDataCon l v
return $ L l (PrefixDataConBuilder nilOL data_con)
tyToDataConBuilder (L l (HsTupleTy _ HsBoxedOrConstraintTuple ts)) = do
let data_con = L l (getRdrName (tupleDataCon Boxed (length ts)))
return $ L l (PrefixDataConBuilder (toOL ts) data_con)
tyToDataConBuilder t =
addFatalError $ Error (ErrInvalidDataCon (unLoc t)) [] (getLoc t)
{- Note [Ambiguous syntactic categories]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
There are places in the grammar where we do not know whether we are parsing an
expression or a pattern without unlimited lookahead (which we do not have in
'happy'):
View patterns:
f (Con a b ) = ... -- 'Con a b' is a pattern
f (Con a b -> x) = ... -- 'Con a b' is an expression
do-notation:
do { Con a b <- x } -- 'Con a b' is a pattern
do { Con a b } -- 'Con a b' is an expression
Guards:
x | True <- p && q = ... -- 'True' is a pattern
x | True = ... -- 'True' is an expression
Top-level value/function declarations (FunBind/PatBind):
f ! a -- TH splice
f ! a = ... -- function declaration
Until we encounter the = sign, we don't know if it's a top-level
TemplateHaskell splice where ! is used, or if it's a function declaration
where ! is bound.
There are also places in the grammar where we do not know whether we are
parsing an expression or a command:
proc x -> do { (stuff) -< x } -- 'stuff' is an expression
proc x -> do { (stuff) } -- 'stuff' is a command
Until we encounter arrow syntax (-<) we don't know whether to parse 'stuff'
as an expression or a command.
In fact, do-notation is subject to both ambiguities:
proc x -> do { (stuff) -< x } -- 'stuff' is an expression
proc x -> do { (stuff) <- f -< x } -- 'stuff' is a pattern
proc x -> do { (stuff) } -- 'stuff' is a command
There are many possible solutions to this problem. For an overview of the ones
we decided against, see Note [Resolving parsing ambiguities: non-taken alternatives]
The solution that keeps basic definitions (such as HsExpr) clean, keeps the
concerns local to the parser, and does not require duplication of hsSyn types,
or an extra pass over the entire AST, is to parse into an overloaded
parser-validator (a so-called tagless final encoding):
class DisambECP b where ...
instance DisambECP (HsCmd GhcPs) where ...
instance DisambECP (HsExp GhcPs) where ...
instance DisambECP (PatBuilder GhcPs) where ...
The 'DisambECP' class contains functions to build and validate 'b'. For example,
to add parentheses we have:
mkHsParPV :: DisambECP b => SrcSpan -> Located b -> PV (Located b)
'mkHsParPV' will wrap the inner value in HsCmdPar for commands, HsPar for
expressions, and 'PatBuilderPar' for patterns (later transformed into ParPat,
see Note [PatBuilder]).
Consider the 'alts' production used to parse case-of alternatives:
alts :: { Located ([AddAnn],[LMatch GhcPs (LHsExpr GhcPs)]) }
: alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
We abstract over LHsExpr GhcPs, and it becomes:
alts :: { forall b. DisambECP b => PV (Located ([AddAnn],[LMatch GhcPs (Located b)])) }
: alts1 { $1 >>= \ $1 ->
return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts { $2 >>= \ $2 ->
return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
Compared to the initial definition, the added bits are:
forall b. DisambECP b => PV ( ... ) -- in the type signature
$1 >>= \ $1 -> return $ -- in one reduction rule
$2 >>= \ $2 -> return $ -- in another reduction rule
The overhead is constant relative to the size of the rest of the reduction
rule, so this approach scales well to large parser productions.
Note that we write ($1 >>= \ $1 -> ...), so the second $1 is in a binding
position and shadows the previous $1. We can do this because internally
'happy' desugars $n to happy_var_n, and the rationale behind this idiom
is to be able to write (sLL $1 $>) later on. The alternative would be to
write this as ($1 >>= \ fresh_name -> ...), but then we couldn't refer
to the last fresh name as $>.
Finally, we instantiate the polymorphic type to a concrete one, and run the
parser-validator, for example:
stmt :: { forall b. DisambECP b => PV (LStmt GhcPs (Located b)) }
e_stmt :: { LStmt GhcPs (LHsExpr GhcPs) }
: stmt {% runPV $1 }
In e_stmt, three things happen:
1. we instantiate: b ~ HsExpr GhcPs
2. we embed the PV computation into P by using runPV
3. we run validation by using a monadic production, {% ... }
At this point the ambiguity is resolved.
-}
{- Note [Resolving parsing ambiguities: non-taken alternatives]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Alternative I, extra constructors in GHC.Hs.Expr
------------------------------------------------
We could add extra constructors to HsExpr to represent command-specific and
pattern-specific syntactic constructs. Under this scheme, we parse patterns
and commands as expressions and rejig later. This is what GHC used to do, and
it polluted 'HsExpr' with irrelevant constructors:
* for commands: 'HsArrForm', 'HsArrApp'
* for patterns: 'EWildPat', 'EAsPat', 'EViewPat', 'ELazyPat'
(As of now, we still do that for patterns, but we plan to fix it).
There are several issues with this:
* The implementation details of parsing are leaking into hsSyn definitions.
* Code that uses HsExpr has to panic on these impossible-after-parsing cases.
* HsExpr is arbitrarily selected as the extension basis. Why not extend
HsCmd or HsPat with extra constructors instead?
Alternative II, extra constructors in GHC.Hs.Expr for GhcPs
-----------------------------------------------------------
We could address some of the problems with Alternative I by using Trees That
Grow and extending HsExpr only in the GhcPs pass. However, GhcPs corresponds to
the output of parsing, not to its intermediate results, so we wouldn't want
them there either.
Alternative III, extra constructors in GHC.Hs.Expr for GhcPrePs
---------------------------------------------------------------
We could introduce a new pass, GhcPrePs, to keep GhcPs pristine.
Unfortunately, creating a new pass would significantly bloat conversion code
and slow down the compiler by adding another linear-time pass over the entire
AST. For example, in order to build HsExpr GhcPrePs, we would need to build
HsLocalBinds GhcPrePs (as part of HsLet), and we never want HsLocalBinds
GhcPrePs.
Alternative IV, sum type and bottom-up data flow
------------------------------------------------
Expressions and commands are disjoint. There are no user inputs that could be
interpreted as either an expression or a command depending on outer context:
5 -- definitely an expression
x -< y -- definitely a command
Even though we have both 'HsLam' and 'HsCmdLam', we can look at
the body to disambiguate:
\p -> 5 -- definitely an expression
\p -> x -< y -- definitely a command
This means we could use a bottom-up flow of information to determine
whether we are parsing an expression or a command, using a sum type
for intermediate results:
Either (LHsExpr GhcPs) (LHsCmd GhcPs)
There are two problems with this:
* We cannot handle the ambiguity between expressions and
patterns, which are not disjoint.
* Bottom-up flow of information leads to poor error messages. Consider
if ... then 5 else (x -< y)
Do we report that '5' is not a valid command or that (x -< y) is not a
valid expression? It depends on whether we want the entire node to be
'HsIf' or 'HsCmdIf', and this information flows top-down, from the
surrounding parsing context (are we in 'proc'?)
Alternative V, backtracking with parser combinators
---------------------------------------------------
One might think we could sidestep the issue entirely by using a backtracking
parser and doing something along the lines of (try pExpr <|> pPat).
Turns out, this wouldn't work very well, as there can be patterns inside
expressions (e.g. via 'case', 'let', 'do') and expressions inside patterns
(e.g. view patterns). To handle this, we would need to backtrack while
backtracking, and unbound levels of backtracking lead to very fragile
performance.
Alternative VI, an intermediate data type
-----------------------------------------
There are common syntactic elements of expressions, commands, and patterns
(e.g. all of them must have balanced parentheses), and we can capture this
common structure in an intermediate data type, Frame:
data Frame
= FrameVar RdrName
-- ^ Identifier: Just, map, BS.length
| FrameTuple [LTupArgFrame] Boxity
-- ^ Tuple (section): (a,b) (a,b,c) (a,,) (,a,)
| FrameTySig LFrame (LHsSigWcType GhcPs)
-- ^ Type signature: x :: ty
| FramePar (SrcSpan, SrcSpan) LFrame
-- ^ Parentheses
| FrameIf LFrame LFrame LFrame
-- ^ If-expression: if p then x else y
| FrameCase LFrame [LFrameMatch]
-- ^ Case-expression: case x of { p1 -> e1; p2 -> e2 }
| FrameDo (HsStmtContext GhcRn) [LFrameStmt]
-- ^ Do-expression: do { s1; a <- s2; s3 }
...
| FrameExpr (HsExpr GhcPs) -- unambiguously an expression
| FramePat (HsPat GhcPs) -- unambiguously a pattern
| FrameCommand (HsCmd GhcPs) -- unambiguously a command
To determine which constructors 'Frame' needs to have, we take the union of
intersections between HsExpr, HsCmd, and HsPat.
The intersection between HsPat and HsExpr:
HsPat = VarPat | TuplePat | SigPat | ParPat | ...
HsExpr = HsVar | ExplicitTuple | ExprWithTySig | HsPar | ...
-------------------------------------------------------------------
Frame = FrameVar | FrameTuple | FrameTySig | FramePar | ...
The intersection between HsCmd and HsExpr:
HsCmd = HsCmdIf | HsCmdCase | HsCmdDo | HsCmdPar
HsExpr = HsIf | HsCase | HsDo | HsPar
------------------------------------------------
Frame = FrameIf | FrameCase | FrameDo | FramePar
The intersection between HsCmd and HsPat:
HsPat = ParPat | ...
HsCmd = HsCmdPar | ...
-----------------------
Frame = FramePar | ...
Take the union of each intersection and this yields the final 'Frame' data
type. The problem with this approach is that we end up duplicating a good
portion of hsSyn:
Frame for HsExpr, HsPat, HsCmd
TupArgFrame for HsTupArg
FrameMatch for Match
FrameStmt for StmtLR
FrameGRHS for GRHS
FrameGRHSs for GRHSs
...
Alternative VII, a product type
-------------------------------
We could avoid the intermediate representation of Alternative VI by parsing
into a product of interpretations directly:
type ExpCmdPat = ( PV (LHsExpr GhcPs)
, PV (LHsCmd GhcPs)
, PV (LHsPat GhcPs) )
This means that in positions where we do not know whether to produce
expression, a pattern, or a command, we instead produce a parser-validator for
each possible option.
Then, as soon as we have parsed far enough to resolve the ambiguity, we pick
the appropriate component of the product, discarding the rest:
checkExpOf3 (e, _, _) = e -- interpret as an expression
checkCmdOf3 (_, c, _) = c -- interpret as a command
checkPatOf3 (_, _, p) = p -- interpret as a pattern
We can easily define ambiguities between arbitrary subsets of interpretations.
For example, when we know ahead of type that only an expression or a command is
possible, but not a pattern, we can use a smaller type:
type ExpCmd = (PV (LHsExpr GhcPs), PV (LHsCmd GhcPs))
checkExpOf2 (e, _) = e -- interpret as an expression
checkCmdOf2 (_, c) = c -- interpret as a command
However, there is a slight problem with this approach, namely code duplication
in parser productions. Consider the 'alts' production used to parse case-of
alternatives:
alts :: { Located ([AddAnn],[LMatch GhcPs (LHsExpr GhcPs)]) }
: alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
Under the new scheme, we have to completely duplicate its type signature and
each reduction rule:
alts :: { ( PV (Located ([AddAnn],[LMatch GhcPs (LHsExpr GhcPs)])) -- as an expression
, PV (Located ([AddAnn],[LMatch GhcPs (LHsCmd GhcPs)])) -- as a command
) }
: alts1
{ ( checkExpOf2 $1 >>= \ $1 ->
return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1)
, checkCmdOf2 $1 >>= \ $1 ->
return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1)
) }
| ';' alts
{ ( checkExpOf2 $2 >>= \ $2 ->
return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2)
, checkCmdOf2 $2 >>= \ $2 ->
return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2)
) }
And the same goes for other productions: 'altslist', 'alts1', 'alt', 'alt_rhs',
'ralt', 'gdpats', 'gdpat', 'exp', ... and so on. That is a lot of code!
Alternative VIII, a function from a GADT
----------------------------------------
We could avoid code duplication of the Alternative VII by representing the product
as a function from a GADT:
data ExpCmdG b where
ExpG :: ExpCmdG HsExpr
CmdG :: ExpCmdG HsCmd
type ExpCmd = forall b. ExpCmdG b -> PV (Located (b GhcPs))
checkExp :: ExpCmd -> PV (LHsExpr GhcPs)
checkCmd :: ExpCmd -> PV (LHsCmd GhcPs)
checkExp f = f ExpG -- interpret as an expression
checkCmd f = f CmdG -- interpret as a command
Consider the 'alts' production used to parse case-of alternatives:
alts :: { Located ([AddAnn],[LMatch GhcPs (LHsExpr GhcPs)]) }
: alts1 { sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts { sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
We abstract over LHsExpr, and it becomes:
alts :: { forall b. ExpCmdG b -> PV (Located ([AddAnn],[LMatch GhcPs (Located (b GhcPs))])) }
: alts1
{ \tag -> $1 tag >>= \ $1 ->
return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts
{ \tag -> $2 tag >>= \ $2 ->
return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
Note that 'ExpCmdG' is a singleton type, the value is completely
determined by the type:
when (b~HsExpr), tag = ExpG
when (b~HsCmd), tag = CmdG
This is a clear indication that we can use a class to pass this value behind
the scenes:
class ExpCmdI b where expCmdG :: ExpCmdG b
instance ExpCmdI HsExpr where expCmdG = ExpG
instance ExpCmdI HsCmd where expCmdG = CmdG
And now the 'alts' production is simplified, as we no longer need to
thread 'tag' explicitly:
alts :: { forall b. ExpCmdI b => PV (Located ([AddAnn],[LMatch GhcPs (Located (b GhcPs))])) }
: alts1 { $1 >>= \ $1 ->
return $ sL1 $1 (fst $ unLoc $1,snd $ unLoc $1) }
| ';' alts { $2 >>= \ $2 ->
return $ sLL $1 $> ((mj AnnSemi $1:(fst $ unLoc $2)),snd $ unLoc $2) }
This encoding works well enough, but introduces an extra GADT unlike the
tagless final encoding, and there's no need for this complexity.
-}
{- Note [PatBuilder]
~~~~~~~~~~~~~~~~~~~~
Unlike HsExpr or HsCmd, the Pat type cannot accommodate all intermediate forms,
so we introduce the notion of a PatBuilder.
Consider a pattern like this:
Con a b c
We parse arguments to "Con" one at a time in the fexp aexp parser production,
building the result with mkHsAppPV, so the intermediate forms are:
1. Con
2. Con a
3. Con a b
4. Con a b c
In 'HsExpr', we have 'HsApp', so the intermediate forms are represented like
this (pseudocode):
1. "Con"
2. HsApp "Con" "a"
3. HsApp (HsApp "Con" "a") "b"
3. HsApp (HsApp (HsApp "Con" "a") "b") "c"
Similarly, in 'HsCmd' we have 'HsCmdApp'. In 'Pat', however, what we have
instead is 'ConPatIn', which is very awkward to modify and thus unsuitable for
the intermediate forms.
We also need an intermediate representation to postpone disambiguation between
FunBind and PatBind. Consider:
a `Con` b = ...
a `fun` b = ...
How do we know that (a `Con` b) is a PatBind but (a `fun` b) is a FunBind? We
learn this by inspecting an intermediate representation in 'isFunLhs' and
seeing that 'Con' is a data constructor but 'f' is not. We need an intermediate
representation capable of representing both a FunBind and a PatBind, so Pat is
insufficient.
PatBuilder is an extension of Pat that is capable of representing intermediate
parsing results for patterns and function bindings:
data PatBuilder p
= PatBuilderPat (Pat p)
| PatBuilderApp (Located (PatBuilder p)) (Located (PatBuilder p))
| PatBuilderOpApp (Located (PatBuilder p)) (Located RdrName) (Located (PatBuilder p))
...
It can represent any pattern via 'PatBuilderPat', but it also has a variety of
other constructors which were added by following a simple principle: we never
pattern match on the pattern stored inside 'PatBuilderPat'.
-}
---------------------------------------------------------------------------
-- Miscellaneous utilities
-- | Check if a fixity is valid. We support bypassing the usual bound checks
-- for some special operators.
checkPrecP
:: Located (SourceText,Int) -- ^ precedence
-> Located (OrdList (Located RdrName)) -- ^ operators
-> P ()
checkPrecP (L l (_,i)) (L _ ol)
| 0 <= i, i <= maxPrecedence = pure ()
| all specialOp ol = pure ()
| otherwise = addFatalError $ Error (ErrPrecedenceOutOfRange i) [] l
where
-- If you change this, consider updating Note [Fixity of (->)] in GHC/Types.hs
specialOp op = unLoc op `elem` [ eqTyCon_RDR
, getRdrName unrestrictedFunTyCon ]
mkRecConstrOrUpdate
:: LHsExpr GhcPs
-> SrcSpan
-> ([LHsRecField GhcPs (LHsExpr GhcPs)], Maybe SrcSpan)
-> PV (HsExpr GhcPs)
mkRecConstrOrUpdate (L l (HsVar _ (L _ c))) _ (fs,dd)
| isRdrDataCon c
= return (mkRdrRecordCon (L l c) (mk_rec_fields fs dd))
mkRecConstrOrUpdate exp _ (fs,dd)
| Just dd_loc <- dd = addFatalError $ Error ErrDotsInRecordUpdate [] dd_loc
| otherwise = return (mkRdrRecordUpd exp (map (fmap mk_rec_upd_field) fs))
mkRdrRecordUpd :: LHsExpr GhcPs -> [LHsRecUpdField GhcPs] -> HsExpr GhcPs
mkRdrRecordUpd exp flds
= RecordUpd { rupd_ext = noExtField
, rupd_expr = exp
, rupd_flds = flds }
mkRdrRecordCon :: Located RdrName -> HsRecordBinds GhcPs -> HsExpr GhcPs
mkRdrRecordCon con flds
= RecordCon { rcon_ext = noExtField, rcon_con_name = con, rcon_flds = flds }
mk_rec_fields :: [Located (HsRecField (GhcPass p) arg)] -> Maybe SrcSpan -> HsRecFields (GhcPass p) arg
mk_rec_fields fs Nothing = HsRecFields { rec_flds = fs, rec_dotdot = Nothing }
mk_rec_fields fs (Just s) = HsRecFields { rec_flds = fs
, rec_dotdot = Just (L s (length fs)) }
mk_rec_upd_field :: HsRecField GhcPs (LHsExpr GhcPs) -> HsRecUpdField GhcPs
mk_rec_upd_field (HsRecField (L loc (FieldOcc _ rdr)) arg pun)
= HsRecField (L loc (Unambiguous noExtField rdr)) arg pun
mkInlinePragma :: SourceText -> (InlineSpec, RuleMatchInfo) -> Maybe Activation
-> InlinePragma
-- The (Maybe Activation) is because the user can omit
-- the activation spec (and usually does)
mkInlinePragma src (inl, match_info) mb_act
= InlinePragma { inl_src = src -- Note [Pragma source text] in GHC.Types.SourceText
, inl_inline = inl
, inl_sat = Nothing
, inl_act = act
, inl_rule = match_info }
where
act = case mb_act of
Just act -> act
Nothing -> -- No phase specified
case inl of
NoInline -> NeverActive
_other -> AlwaysActive
-----------------------------------------------------------------------------
-- utilities for foreign declarations
-- construct a foreign import declaration
--
mkImport :: Located CCallConv
-> Located Safety
-> (Located StringLiteral, Located RdrName, LHsSigType GhcPs)
-> P (HsDecl GhcPs)
mkImport cconv safety (L loc (StringLiteral esrc entity), v, ty) =
case unLoc cconv of
CCallConv -> mkCImport
CApiConv -> mkCImport
StdCallConv -> mkCImport
PrimCallConv -> mkOtherImport
JavaScriptCallConv -> mkOtherImport
where
-- Parse a C-like entity string of the following form:
-- "[static] [chname] [&] [cid]" | "dynamic" | "wrapper"
-- If 'cid' is missing, the function name 'v' is used instead as symbol
-- name (cf section 8.5.1 in Haskell 2010 report).
mkCImport = do
let e = unpackFS entity
case parseCImport cconv safety (mkExtName (unLoc v)) e (L loc esrc) of
Nothing -> addFatalError $ Error ErrMalformedEntityString [] loc
Just importSpec -> returnSpec importSpec
-- currently, all the other import conventions only support a symbol name in
-- the entity string. If it is missing, we use the function name instead.
mkOtherImport = returnSpec importSpec
where
entity' = if nullFS entity
then mkExtName (unLoc v)
else entity
funcTarget = CFunction (StaticTarget esrc entity' Nothing True)
importSpec = CImport cconv safety Nothing funcTarget (L loc esrc)
returnSpec spec = return $ ForD noExtField $ ForeignImport
{ fd_i_ext = noExtField
, fd_name = v
, fd_sig_ty = ty
, fd_fi = spec
}
-- the string "foo" is ambiguous: either a header or a C identifier. The
-- C identifier case comes first in the alternatives below, so we pick
-- that one.
parseCImport :: Located CCallConv -> Located Safety -> FastString -> String
-> Located SourceText
-> Maybe ForeignImport
parseCImport cconv safety nm str sourceText =
listToMaybe $ map fst $ filter (null.snd) $
readP_to_S parse str
where
parse = do
skipSpaces
r <- choice [
string "dynamic" >> return (mk Nothing (CFunction DynamicTarget)),
string "wrapper" >> return (mk Nothing CWrapper),
do optional (token "static" >> skipSpaces)
((mk Nothing <$> cimp nm) +++
(do h <- munch1 hdr_char
skipSpaces
mk (Just (Header (SourceText h) (mkFastString h)))
<$> cimp nm))
]
skipSpaces
return r
token str = do _ <- string str
toks <- look
case toks of
c : _
| id_char c -> pfail
_ -> return ()
mk h n = CImport cconv safety h n sourceText
hdr_char c = not (isSpace c)
-- header files are filenames, which can contain
-- pretty much any char (depending on the platform),
-- so just accept any non-space character
id_first_char c = isAlpha c || c == '_'
id_char c = isAlphaNum c || c == '_'
cimp nm = (ReadP.char '&' >> skipSpaces >> CLabel <$> cid)
+++ (do isFun <- case unLoc cconv of
CApiConv ->
option True
(do token "value"
skipSpaces
return False)
_ -> return True
cid' <- cid
return (CFunction (StaticTarget NoSourceText cid'
Nothing isFun)))
where
cid = return nm +++
(do c <- satisfy id_first_char
cs <- many (satisfy id_char)
return (mkFastString (c:cs)))
-- construct a foreign export declaration
--
mkExport :: Located CCallConv
-> (Located StringLiteral, Located RdrName, LHsSigType GhcPs)
-> P (HsDecl GhcPs)
mkExport (L lc cconv) (L le (StringLiteral esrc entity), v, ty)
= return $ ForD noExtField $
ForeignExport { fd_e_ext = noExtField, fd_name = v, fd_sig_ty = ty
, fd_fe = CExport (L lc (CExportStatic esrc entity' cconv))
(L le esrc) }
where
entity' | nullFS entity = mkExtName (unLoc v)
| otherwise = entity
-- Supplying the ext_name in a foreign decl is optional; if it
-- isn't there, the Haskell name is assumed. Note that no transformation
-- of the Haskell name is then performed, so if you foreign export (++),
-- it's external name will be "++". Too bad; it's important because we don't
-- want z-encoding (e.g. names with z's in them shouldn't be doubled)
--
mkExtName :: RdrName -> CLabelString
mkExtName rdrNm = mkFastString (occNameString (rdrNameOcc rdrNm))
--------------------------------------------------------------------------------
-- Help with module system imports/exports
data ImpExpSubSpec = ImpExpAbs
| ImpExpAll
| ImpExpList [Located ImpExpQcSpec]
| ImpExpAllWith [Located ImpExpQcSpec]
data ImpExpQcSpec = ImpExpQcName (Located RdrName)
| ImpExpQcType (Located RdrName)
| ImpExpQcWildcard
mkModuleImpExp :: Located ImpExpQcSpec -> ImpExpSubSpec -> P (IE GhcPs)
mkModuleImpExp (L l specname) subs =
case subs of
ImpExpAbs
| isVarNameSpace (rdrNameSpace name)
-> return $ IEVar noExtField (L l (ieNameFromSpec specname))
| otherwise -> IEThingAbs noExtField . L l <$> nameT
ImpExpAll -> IEThingAll noExtField . L l <$> nameT
ImpExpList xs ->
(\newName -> IEThingWith noExtField (L l newName)
NoIEWildcard (wrapped xs) []) <$> nameT
ImpExpAllWith xs ->
do allowed <- getBit PatternSynonymsBit
if allowed
then
let withs = map unLoc xs
pos = maybe NoIEWildcard IEWildcard
(findIndex isImpExpQcWildcard withs)
ies = wrapped $ filter (not . isImpExpQcWildcard . unLoc) xs
in (\newName
-> IEThingWith noExtField (L l newName) pos ies [])
<$> nameT
else addFatalError $ Error ErrIllegalPatSynExport [] l
where
name = ieNameVal specname
nameT =
if isVarNameSpace (rdrNameSpace name)
then addFatalError $ Error (ErrVarForTyCon name) [] l
else return $ ieNameFromSpec specname
ieNameVal (ImpExpQcName ln) = unLoc ln
ieNameVal (ImpExpQcType ln) = unLoc ln
ieNameVal (ImpExpQcWildcard) = panic "ieNameVal got wildcard"
ieNameFromSpec (ImpExpQcName ln) = IEName ln
ieNameFromSpec (ImpExpQcType ln) = IEType ln
ieNameFromSpec (ImpExpQcWildcard) = panic "ieName got wildcard"
wrapped = map (mapLoc ieNameFromSpec)
mkTypeImpExp :: Located RdrName -- TcCls or Var name space
-> P (Located RdrName)
mkTypeImpExp name =
do allowed <- getBit ExplicitNamespacesBit
unless allowed $ addError $ Error ErrIllegalExplicitNamespace [] (getLoc name)
return (fmap (`setRdrNameSpace` tcClsName) name)
checkImportSpec :: Located [LIE GhcPs] -> P (Located [LIE GhcPs])
checkImportSpec ie@(L _ specs) =
case [l | (L l (IEThingWith _ _ (IEWildcard _) _ _)) <- specs] of
[] -> return ie
(l:_) -> importSpecError l
where
importSpecError l =
addFatalError $ Error ErrIllegalImportBundleForm [] l
-- In the correct order
mkImpExpSubSpec :: [Located ImpExpQcSpec] -> P ([AddAnn], ImpExpSubSpec)
mkImpExpSubSpec [] = return ([], ImpExpList [])
mkImpExpSubSpec [L _ ImpExpQcWildcard] =
return ([], ImpExpAll)
mkImpExpSubSpec xs =
if (any (isImpExpQcWildcard . unLoc) xs)
then return $ ([], ImpExpAllWith xs)
else return $ ([], ImpExpList xs)
isImpExpQcWildcard :: ImpExpQcSpec -> Bool
isImpExpQcWildcard ImpExpQcWildcard = True
isImpExpQcWildcard _ = False
-----------------------------------------------------------------------------
-- Warnings and failures
warnPrepositiveQualifiedModule :: SrcSpan -> P ()
warnPrepositiveQualifiedModule span =
addWarning Opt_WarnPrepositiveQualifiedModule (WarnImportPreQualified span)
failOpNotEnabledImportQualifiedPost :: SrcSpan -> P ()
failOpNotEnabledImportQualifiedPost loc = addError $ Error ErrImportPostQualified [] loc
failOpImportQualifiedTwice :: SrcSpan -> P ()
failOpImportQualifiedTwice loc = addError $ Error ErrImportQualifiedTwice [] loc
warnStarIsType :: SrcSpan -> P ()
warnStarIsType span = addWarning Opt_WarnStarIsType (WarnStarIsType span)
failOpFewArgs :: MonadP m => Located RdrName -> m a
failOpFewArgs (L loc op) =
do { star_is_type <- getBit StarIsTypeBit
; addFatalError $ Error (ErrOpFewArgs (StarIsType star_is_type) op) [] loc }
-----------------------------------------------------------------------------
-- Misc utils
data PV_Context =
PV_Context
{ pv_options :: ParserOpts
, pv_hints :: [Hint] -- See Note [Parser-Validator Hint]
}
data PV_Accum =
PV_Accum
{ pv_warnings :: Bag Warning
, pv_errors :: Bag Error
, pv_annotations :: [(ApiAnnKey,[RealSrcSpan])]
, pv_comment_q :: [RealLocated AnnotationComment]
, pv_annotations_comments :: [(RealSrcSpan,[RealLocated AnnotationComment])]
}
data PV_Result a = PV_Ok PV_Accum a | PV_Failed PV_Accum
-- During parsing, we make use of several monadic effects: reporting parse errors,
-- accumulating warnings, adding API annotations, and checking for extensions. These
-- effects are captured by the 'MonadP' type class.
--
-- Sometimes we need to postpone some of these effects to a later stage due to
-- ambiguities described in Note [Ambiguous syntactic categories].
-- We could use two layers of the P monad, one for each stage:
--
-- abParser :: forall x. DisambAB x => P (P x)
--
-- The outer layer of P consumes the input and builds the inner layer, which
-- validates the input. But this type is not particularly helpful, as it obscures
-- the fact that the inner layer of P never consumes any input.
--
-- For clarity, we introduce the notion of a parser-validator: a parser that does
-- not consume any input, but may fail or use other effects. Thus we have:
--
-- abParser :: forall x. DisambAB x => P (PV x)
--
newtype PV a = PV { unPV :: PV_Context -> PV_Accum -> PV_Result a }
instance Functor PV where
fmap = liftM
instance Applicative PV where
pure a = a `seq` PV (\_ acc -> PV_Ok acc a)
(<*>) = ap
instance Monad PV where
m >>= f = PV $ \ctx acc ->
case unPV m ctx acc of
PV_Ok acc' a -> unPV (f a) ctx acc'
PV_Failed acc' -> PV_Failed acc'
runPV :: PV a -> P a
runPV = runPV_hints []
runPV_hints :: [Hint] -> PV a -> P a
runPV_hints hints m =
P $ \s ->
let
pv_ctx = PV_Context
{ pv_options = options s
, pv_hints = hints }
pv_acc = PV_Accum
{ pv_warnings = warnings s
, pv_errors = errors s
, pv_annotations = annotations s
, pv_comment_q = comment_q s
, pv_annotations_comments = annotations_comments s }
mkPState acc' =
s { warnings = pv_warnings acc'
, errors = pv_errors acc'
, annotations = pv_annotations acc'
, comment_q = pv_comment_q acc'
, annotations_comments = pv_annotations_comments acc' }
in
case unPV m pv_ctx pv_acc of
PV_Ok acc' a -> POk (mkPState acc') a
PV_Failed acc' -> PFailed (mkPState acc')
add_hint :: Hint -> PV a -> PV a
add_hint hint m =
let modifyHint ctx = ctx{pv_hints = pv_hints ctx ++ [hint]} in
PV (\ctx acc -> unPV m (modifyHint ctx) acc)
instance MonadP PV where
addError err@(Error e hints loc) =
PV $ \ctx acc ->
let err' | null (pv_hints ctx) = err
| otherwise = Error e (hints ++ pv_hints ctx) loc
in PV_Ok acc{pv_errors = err' `consBag` pv_errors acc} ()
addWarning option w =
PV $ \ctx acc ->
if warnopt option (pv_options ctx)
then PV_Ok acc{pv_warnings= w `consBag` pv_warnings acc} ()
else PV_Ok acc ()
addFatalError err =
addError err >> PV (const PV_Failed)
getBit ext =
PV $ \ctx acc ->
let b = ext `xtest` pExtsBitmap (pv_options ctx) in
PV_Ok acc $! b
addAnnotation (RealSrcSpan l _) a (RealSrcSpan v _) =
PV $ \_ acc ->
let
(comment_q', new_ann_comments) = allocateComments l (pv_comment_q acc)
annotations_comments' = new_ann_comments ++ pv_annotations_comments acc
annotations' = ((l,a), [v]) : pv_annotations acc
acc' = acc
{ pv_annotations = annotations'
, pv_comment_q = comment_q'
, pv_annotations_comments = annotations_comments' }
in
PV_Ok acc' ()
addAnnotation _ _ _ = return ()
{- Note [Parser-Validator Hint]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A PV computation is parametrized by a hint for error messages, which can be set
depending on validation context. We use this in checkPattern to fix #984.
Consider this example, where the user has forgotten a 'do':
f _ = do
x <- computation
case () of
_ ->
result <- computation
case () of () -> undefined
GHC parses it as follows:
f _ = do
x <- computation
(case () of
_ ->
result) <- computation
case () of () -> undefined
Note that this fragment is parsed as a pattern:
case () of
_ ->
result
We attempt to detect such cases and add a hint to the error messages:
T984.hs:6:9:
Parse error in pattern: case () of { _ -> result }
Possibly caused by a missing 'do'?
The "Possibly caused by a missing 'do'?" suggestion is the hint that is passed
as the 'pv_hints' field 'PV_Context'. When validating in a context other than
'bindpat' (a pattern to the left of <-), we set the hint to 'empty' and it has
no effect on the error messages.
-}
-- | Hint about bang patterns, assuming @BangPatterns@ is off.
hintBangPat :: SrcSpan -> Pat GhcPs -> PV ()
hintBangPat span e = do
bang_on <- getBit BangPatBit
unless bang_on $
addError $ Error (ErrIllegalBangPattern e) [] span
mkSumOrTupleExpr :: SrcSpan -> Boxity -> SumOrTuple (HsExpr GhcPs) -> PV (LHsExpr GhcPs)
-- Tuple
mkSumOrTupleExpr l boxity (Tuple es) =
return $ L l (ExplicitTuple noExtField (map toTupArg es) boxity)
where
toTupArg :: Located (Maybe (LHsExpr GhcPs)) -> LHsTupArg GhcPs
toTupArg = mapLoc (maybe missingTupArg (Present noExtField))
-- Sum
mkSumOrTupleExpr l Unboxed (Sum alt arity e) =
return $ L l (ExplicitSum noExtField alt arity e)
mkSumOrTupleExpr l Boxed a@Sum{} =
addFatalError $ Error (ErrUnsupportedBoxedSumExpr a) [] l
mkSumOrTuplePat :: SrcSpan -> Boxity -> SumOrTuple (PatBuilder GhcPs) -> PV (Located (PatBuilder GhcPs))
-- Tuple
mkSumOrTuplePat l boxity (Tuple ps) = do
ps' <- traverse toTupPat ps
return $ L l (PatBuilderPat (TuplePat noExtField ps' boxity))
where
toTupPat :: Located (Maybe (Located (PatBuilder GhcPs))) -> PV (LPat GhcPs)
toTupPat (L l p) = case p of
Nothing -> addFatalError $ Error ErrTupleSectionInPat [] l
Just p' -> checkLPat p'
-- Sum
mkSumOrTuplePat l Unboxed (Sum alt arity p) = do
p' <- checkLPat p
return $ L l (PatBuilderPat (SumPat noExtField p' alt arity))
mkSumOrTuplePat l Boxed a@Sum{} =
addFatalError $ Error (ErrUnsupportedBoxedSumPat a) [] l
mkLHsOpTy :: LHsType GhcPs -> Located RdrName -> LHsType GhcPs -> LHsType GhcPs
mkLHsOpTy x op y =
let loc = getLoc x `combineSrcSpans` getLoc op `combineSrcSpans` getLoc y
in L loc (mkHsOpTy x op y)
mkMultTy :: IsUnicodeSyntax -> Located Token -> LHsType GhcPs -> (HsArrow GhcPs, AddAnn)
mkMultTy u tok t@(L _ (HsTyLit _ (HsNumTy _ 1)))
= (HsLinearArrow u, AddAnn AnnPercentOne (combineLocs tok t))
mkMultTy u tok t = (HsExplicitMult u t, AddAnn AnnPercent (getLoc tok))
-----------------------------------------------------------------------------
-- Token symbols
starSym :: Bool -> String
starSym True = "★"
starSym False = "*"