ghc-8.2.1: basicTypes/RdrName.hs
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}
{-# LANGUAGE CPP, DeriveDataTypeable #-}
-- |
-- #name_types#
-- GHC uses several kinds of name internally:
--
-- * 'OccName.OccName': see "OccName#name_types"
--
-- * 'RdrName.RdrName' is the type of names that come directly from the parser. They
-- have not yet had their scoping and binding resolved by the renamer and can be
-- thought of to a first approximation as an 'OccName.OccName' with an optional module
-- qualifier
--
-- * 'Name.Name': see "Name#name_types"
--
-- * 'Id.Id': see "Id#name_types"
--
-- * 'Var.Var': see "Var#name_types"
module RdrName (
-- * The main type
RdrName(..), -- Constructors exported only to BinIface
-- ** Construction
mkRdrUnqual, mkRdrQual,
mkUnqual, mkVarUnqual, mkQual, mkOrig,
nameRdrName, getRdrName,
-- ** Destruction
rdrNameOcc, rdrNameSpace, demoteRdrName,
isRdrDataCon, isRdrTyVar, isRdrTc, isQual, isQual_maybe, isUnqual,
isOrig, isOrig_maybe, isExact, isExact_maybe, isSrcRdrName,
-- * Local mapping of 'RdrName' to 'Name.Name'
LocalRdrEnv, emptyLocalRdrEnv, extendLocalRdrEnv, extendLocalRdrEnvList,
lookupLocalRdrEnv, lookupLocalRdrOcc,
elemLocalRdrEnv, inLocalRdrEnvScope,
localRdrEnvElts, delLocalRdrEnvList,
-- * Global mapping of 'RdrName' to 'GlobalRdrElt's
GlobalRdrEnv, emptyGlobalRdrEnv, mkGlobalRdrEnv, plusGlobalRdrEnv,
lookupGlobalRdrEnv, extendGlobalRdrEnv, greOccName, shadowNames,
pprGlobalRdrEnv, globalRdrEnvElts,
lookupGRE_RdrName, lookupGRE_Name, lookupGRE_FieldLabel,
getGRE_NameQualifier_maybes,
transformGREs, pickGREs, pickGREsModExp,
-- * GlobalRdrElts
gresFromAvails, gresFromAvail, localGREsFromAvail, availFromGRE,
greUsedRdrName, greRdrNames, greSrcSpan, greQualModName,
gresToAvailInfo,
-- ** Global 'RdrName' mapping elements: 'GlobalRdrElt', 'Provenance', 'ImportSpec'
GlobalRdrElt(..), isLocalGRE, isRecFldGRE, greLabel,
unQualOK, qualSpecOK, unQualSpecOK,
pprNameProvenance,
Parent(..),
ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
importSpecLoc, importSpecModule, isExplicitItem, bestImport
) where
#include "HsVersions.h"
import Module
import Name
import Avail
import NameSet
import Maybes
import SrcLoc
import FastString
import FieldLabel
import Outputable
import Unique
import UniqFM
import UniqSet
import Util
import NameEnv
import Data.Data
import Data.List( sortBy, foldl', nub )
{-
************************************************************************
* *
\subsection{The main data type}
* *
************************************************************************
-}
-- | Reader Name
--
-- Do not use the data constructors of RdrName directly: prefer the family
-- of functions that creates them, such as 'mkRdrUnqual'
--
-- - Note: A Located RdrName will only have API Annotations if it is a
-- compound one,
-- e.g.
--
-- > `bar`
-- > ( ~ )
--
-- - 'ApiAnnotation.AnnKeywordId' : 'ApiAnnotation.AnnType',
-- 'ApiAnnotation.AnnOpen' @'('@ or @'['@ or @'[:'@,
-- 'ApiAnnotation.AnnClose' @')'@ or @']'@ or @':]'@,,
-- 'ApiAnnotation.AnnBackquote' @'`'@,
-- 'ApiAnnotation.AnnVal','ApiAnnotation.AnnTildehsh',
-- 'ApiAnnotation.AnnTilde',
-- For details on above see note [Api annotations] in ApiAnnotation
data RdrName
= Unqual OccName
-- ^ Unqualified name
--
-- Used for ordinary, unqualified occurrences, e.g. @x@, @y@ or @Foo@.
-- Create such a 'RdrName' with 'mkRdrUnqual'
| Qual ModuleName OccName
-- ^ Qualified name
--
-- A qualified name written by the user in
-- /source/ code. The module isn't necessarily
-- the module where the thing is defined;
-- just the one from which it is imported.
-- Examples are @Bar.x@, @Bar.y@ or @Bar.Foo@.
-- Create such a 'RdrName' with 'mkRdrQual'
| Orig Module OccName
-- ^ Original name
--
-- An original name; the module is the /defining/ module.
-- This is used when GHC generates code that will be fed
-- into the renamer (e.g. from deriving clauses), but where
-- we want to say \"Use Prelude.map dammit\". One of these
-- can be created with 'mkOrig'
| Exact Name
-- ^ Exact name
--
-- We know exactly the 'Name'. This is used:
--
-- (1) When the parser parses built-in syntax like @[]@
-- and @(,)@, but wants a 'RdrName' from it
--
-- (2) By Template Haskell, when TH has generated a unique name
--
-- Such a 'RdrName' can be created by using 'getRdrName' on a 'Name'
deriving Data
{-
************************************************************************
* *
\subsection{Simple functions}
* *
************************************************************************
-}
instance HasOccName RdrName where
occName = rdrNameOcc
rdrNameOcc :: RdrName -> OccName
rdrNameOcc (Qual _ occ) = occ
rdrNameOcc (Unqual occ) = occ
rdrNameOcc (Orig _ occ) = occ
rdrNameOcc (Exact name) = nameOccName name
rdrNameSpace :: RdrName -> NameSpace
rdrNameSpace = occNameSpace . rdrNameOcc
-- demoteRdrName lowers the NameSpace of RdrName.
-- see Note [Demotion] in OccName
demoteRdrName :: RdrName -> Maybe RdrName
demoteRdrName (Unqual occ) = fmap Unqual (demoteOccName occ)
demoteRdrName (Qual m occ) = fmap (Qual m) (demoteOccName occ)
demoteRdrName (Orig _ _) = panic "demoteRdrName"
demoteRdrName (Exact _) = panic "demoteRdrName"
-- These two are the basic constructors
mkRdrUnqual :: OccName -> RdrName
mkRdrUnqual occ = Unqual occ
mkRdrQual :: ModuleName -> OccName -> RdrName
mkRdrQual mod occ = Qual mod occ
mkOrig :: Module -> OccName -> RdrName
mkOrig mod occ = Orig mod occ
---------------
-- These two are used when parsing source files
-- They do encode the module and occurrence names
mkUnqual :: NameSpace -> FastString -> RdrName
mkUnqual sp n = Unqual (mkOccNameFS sp n)
mkVarUnqual :: FastString -> RdrName
mkVarUnqual n = Unqual (mkVarOccFS n)
-- | Make a qualified 'RdrName' in the given namespace and where the 'ModuleName' and
-- the 'OccName' are taken from the first and second elements of the tuple respectively
mkQual :: NameSpace -> (FastString, FastString) -> RdrName
mkQual sp (m, n) = Qual (mkModuleNameFS m) (mkOccNameFS sp n)
getRdrName :: NamedThing thing => thing -> RdrName
getRdrName name = nameRdrName (getName name)
nameRdrName :: Name -> RdrName
nameRdrName name = Exact name
-- Keep the Name even for Internal names, so that the
-- unique is still there for debug printing, particularly
-- of Types (which are converted to IfaceTypes before printing)
nukeExact :: Name -> RdrName
nukeExact n
| isExternalName n = Orig (nameModule n) (nameOccName n)
| otherwise = Unqual (nameOccName n)
isRdrDataCon :: RdrName -> Bool
isRdrTyVar :: RdrName -> Bool
isRdrTc :: RdrName -> Bool
isRdrDataCon rn = isDataOcc (rdrNameOcc rn)
isRdrTyVar rn = isTvOcc (rdrNameOcc rn)
isRdrTc rn = isTcOcc (rdrNameOcc rn)
isSrcRdrName :: RdrName -> Bool
isSrcRdrName (Unqual _) = True
isSrcRdrName (Qual _ _) = True
isSrcRdrName _ = False
isUnqual :: RdrName -> Bool
isUnqual (Unqual _) = True
isUnqual _ = False
isQual :: RdrName -> Bool
isQual (Qual _ _) = True
isQual _ = False
isQual_maybe :: RdrName -> Maybe (ModuleName, OccName)
isQual_maybe (Qual m n) = Just (m,n)
isQual_maybe _ = Nothing
isOrig :: RdrName -> Bool
isOrig (Orig _ _) = True
isOrig _ = False
isOrig_maybe :: RdrName -> Maybe (Module, OccName)
isOrig_maybe (Orig m n) = Just (m,n)
isOrig_maybe _ = Nothing
isExact :: RdrName -> Bool
isExact (Exact _) = True
isExact _ = False
isExact_maybe :: RdrName -> Maybe Name
isExact_maybe (Exact n) = Just n
isExact_maybe _ = Nothing
{-
************************************************************************
* *
\subsection{Instances}
* *
************************************************************************
-}
instance Outputable RdrName where
ppr (Exact name) = ppr name
ppr (Unqual occ) = ppr occ
ppr (Qual mod occ) = ppr mod <> dot <> ppr occ
ppr (Orig mod occ) = getPprStyle (\sty -> pprModulePrefix sty mod occ <> ppr occ)
instance OutputableBndr RdrName where
pprBndr _ n
| isTvOcc (rdrNameOcc n) = char '@' <+> ppr n
| otherwise = ppr n
pprInfixOcc rdr = pprInfixVar (isSymOcc (rdrNameOcc rdr)) (ppr rdr)
pprPrefixOcc rdr
| Just name <- isExact_maybe rdr = pprPrefixName name
-- pprPrefixName has some special cases, so
-- we delegate to them rather than reproduce them
| otherwise = pprPrefixVar (isSymOcc (rdrNameOcc rdr)) (ppr rdr)
instance Eq RdrName where
(Exact n1) == (Exact n2) = n1==n2
-- Convert exact to orig
(Exact n1) == r2@(Orig _ _) = nukeExact n1 == r2
r1@(Orig _ _) == (Exact n2) = r1 == nukeExact n2
(Orig m1 o1) == (Orig m2 o2) = m1==m2 && o1==o2
(Qual m1 o1) == (Qual m2 o2) = m1==m2 && o1==o2
(Unqual o1) == (Unqual o2) = o1==o2
_ == _ = False
instance Ord RdrName where
a <= b = case (a `compare` b) of { LT -> True; EQ -> True; GT -> False }
a < b = case (a `compare` b) of { LT -> True; EQ -> False; GT -> False }
a >= b = case (a `compare` b) of { LT -> False; EQ -> True; GT -> True }
a > b = case (a `compare` b) of { LT -> False; EQ -> False; GT -> True }
-- Exact < Unqual < Qual < Orig
-- [Note: Apr 2004] We used to use nukeExact to convert Exact to Orig
-- before comparing so that Prelude.map == the exact Prelude.map, but
-- that meant that we reported duplicates when renaming bindings
-- generated by Template Haskell; e.g
-- do { n1 <- newName "foo"; n2 <- newName "foo";
-- <decl involving n1,n2> }
-- I think we can do without this conversion
compare (Exact n1) (Exact n2) = n1 `compare` n2
compare (Exact _) _ = LT
compare (Unqual _) (Exact _) = GT
compare (Unqual o1) (Unqual o2) = o1 `compare` o2
compare (Unqual _) _ = LT
compare (Qual _ _) (Exact _) = GT
compare (Qual _ _) (Unqual _) = GT
compare (Qual m1 o1) (Qual m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
compare (Qual _ _) (Orig _ _) = LT
compare (Orig m1 o1) (Orig m2 o2) = (o1 `compare` o2) `thenCmp` (m1 `compare` m2)
compare (Orig _ _) _ = GT
{-
************************************************************************
* *
LocalRdrEnv
* *
************************************************************************
-}
-- | Local Reader Environment
--
-- This environment is used to store local bindings
-- (@let@, @where@, lambda, @case@).
-- It is keyed by OccName, because we never use it for qualified names
-- We keep the current mapping, *and* the set of all Names in scope
-- Reason: see Note [Splicing Exact names] in RnEnv
data LocalRdrEnv = LRE { lre_env :: OccEnv Name
, lre_in_scope :: NameSet }
instance Outputable LocalRdrEnv where
ppr (LRE {lre_env = env, lre_in_scope = ns})
= hang (text "LocalRdrEnv {")
2 (vcat [ text "env =" <+> pprOccEnv ppr_elt env
, text "in_scope ="
<+> pprUFM (getUniqSet ns) (braces . pprWithCommas ppr)
] <+> char '}')
where
ppr_elt name = parens (ppr (getUnique (nameOccName name))) <+> ppr name
-- So we can see if the keys line up correctly
emptyLocalRdrEnv :: LocalRdrEnv
emptyLocalRdrEnv = LRE { lre_env = emptyOccEnv
, lre_in_scope = emptyNameSet }
extendLocalRdrEnv :: LocalRdrEnv -> Name -> LocalRdrEnv
-- The Name should be a non-top-level thing
extendLocalRdrEnv lre@(LRE { lre_env = env, lre_in_scope = ns }) name
= WARN( isExternalName name, ppr name )
lre { lre_env = extendOccEnv env (nameOccName name) name
, lre_in_scope = extendNameSet ns name }
extendLocalRdrEnvList :: LocalRdrEnv -> [Name] -> LocalRdrEnv
extendLocalRdrEnvList lre@(LRE { lre_env = env, lre_in_scope = ns }) names
= WARN( any isExternalName names, ppr names )
lre { lre_env = extendOccEnvList env [(nameOccName n, n) | n <- names]
, lre_in_scope = extendNameSetList ns names }
lookupLocalRdrEnv :: LocalRdrEnv -> RdrName -> Maybe Name
lookupLocalRdrEnv (LRE { lre_env = env, lre_in_scope = ns }) rdr
| Unqual occ <- rdr
= lookupOccEnv env occ
-- See Note [Local bindings with Exact Names]
| Exact name <- rdr
, name `elemNameSet` ns
= Just name
| otherwise
= Nothing
lookupLocalRdrOcc :: LocalRdrEnv -> OccName -> Maybe Name
lookupLocalRdrOcc (LRE { lre_env = env }) occ = lookupOccEnv env occ
elemLocalRdrEnv :: RdrName -> LocalRdrEnv -> Bool
elemLocalRdrEnv rdr_name (LRE { lre_env = env, lre_in_scope = ns })
= case rdr_name of
Unqual occ -> occ `elemOccEnv` env
Exact name -> name `elemNameSet` ns -- See Note [Local bindings with Exact Names]
Qual {} -> False
Orig {} -> False
localRdrEnvElts :: LocalRdrEnv -> [Name]
localRdrEnvElts (LRE { lre_env = env }) = occEnvElts env
inLocalRdrEnvScope :: Name -> LocalRdrEnv -> Bool
-- This is the point of the NameSet
inLocalRdrEnvScope name (LRE { lre_in_scope = ns }) = name `elemNameSet` ns
delLocalRdrEnvList :: LocalRdrEnv -> [OccName] -> LocalRdrEnv
delLocalRdrEnvList lre@(LRE { lre_env = env }) occs
= lre { lre_env = delListFromOccEnv env occs }
{-
Note [Local bindings with Exact Names]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
With Template Haskell we can make local bindings that have Exact Names.
Computing shadowing etc may use elemLocalRdrEnv (at least it certainly
does so in RnTpes.bindHsQTyVars), so for an Exact Name we must consult
the in-scope-name-set.
************************************************************************
* *
GlobalRdrEnv
* *
************************************************************************
-}
-- | Global Reader Environment
type GlobalRdrEnv = OccEnv [GlobalRdrElt]
-- ^ Keyed by 'OccName'; when looking up a qualified name
-- we look up the 'OccName' part, and then check the 'Provenance'
-- to see if the appropriate qualification is valid. This
-- saves routinely doubling the size of the env by adding both
-- qualified and unqualified names to the domain.
--
-- The list in the codomain is required because there may be name clashes
-- These only get reported on lookup, not on construction
--
-- INVARIANT 1: All the members of the list have distinct
-- 'gre_name' fields; that is, no duplicate Names
--
-- INVARIANT 2: Imported provenance => Name is an ExternalName
-- However LocalDefs can have an InternalName. This
-- happens only when type-checking a [d| ... |] Template
-- Haskell quotation; see this note in RnNames
-- Note [Top-level Names in Template Haskell decl quotes]
--
-- INVARIANT 3: If the GlobalRdrEnv maps [occ -> gre], then
-- greOccName gre = occ
--
-- NB: greOccName gre is usually the same as
-- nameOccName (gre_name gre), but not always in the
-- case of record seectors; see greOccName
-- | Global Reader Element
--
-- An element of the 'GlobalRdrEnv'
data GlobalRdrElt
= GRE { gre_name :: Name
, gre_par :: Parent
, gre_lcl :: Bool -- ^ True <=> the thing was defined locally
, gre_imp :: [ImportSpec] -- ^ In scope through these imports
} deriving (Data, Eq)
-- INVARIANT: either gre_lcl = True or gre_imp is non-empty
-- See Note [GlobalRdrElt provenance]
-- | The children of a Name are the things that are abbreviated by the ".."
-- notation in export lists. See Note [Parents]
data Parent = NoParent
| ParentIs { par_is :: Name }
| FldParent { par_is :: Name, par_lbl :: Maybe FieldLabelString }
-- ^ See Note [Parents for record fields]
deriving (Eq, Data, Typeable)
instance Outputable Parent where
ppr NoParent = empty
ppr (ParentIs n) = text "parent:" <> ppr n
ppr (FldParent n f) = text "fldparent:"
<> ppr n <> colon <> ppr f
plusParent :: Parent -> Parent -> Parent
-- See Note [Combining parents]
plusParent p1@(ParentIs _) p2 = hasParent p1 p2
plusParent p1@(FldParent _ _) p2 = hasParent p1 p2
plusParent p1 p2@(ParentIs _) = hasParent p2 p1
plusParent p1 p2@(FldParent _ _) = hasParent p2 p1
plusParent _ _ = NoParent
hasParent :: Parent -> Parent -> Parent
#ifdef DEBUG
hasParent p NoParent = p
hasParent p p'
| p /= p' = pprPanic "hasParent" (ppr p <+> ppr p') -- Parents should agree
#endif
hasParent p _ = p
{- Note [GlobalRdrElt provenance]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The gre_lcl and gre_imp fields of a GlobalRdrElt describe its "provenance",
i.e. how the Name came to be in scope. It can be in scope two ways:
- gre_lcl = True: it is bound in this module
- gre_imp: a list of all the imports that brought it into scope
It's an INVARIANT that you have one or the other; that is, either
gre_lcl is True, or gre_imp is non-empty.
It is just possible to have *both* if there is a module loop: a Name
is defined locally in A, and also brought into scope by importing a
module that SOURCE-imported A. Exapmle (Trac #7672):
A.hs-boot module A where
data T
B.hs module B(Decl.T) where
import {-# SOURCE #-} qualified A as Decl
A.hs module A where
import qualified B
data T = Z | S B.T
In A.hs, 'T' is locally bound, *and* imported as B.T.
Note [Parents]
~~~~~~~~~~~~~~~~~
Parent Children
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
data T Data constructors
Record-field ids
data family T Data constructors and record-field ids
of all visible data instances of T
class C Class operations
Associated type constructors
~~~~~~~~~~~~~~~~~~~~~~~~~
Constructor Meaning
~~~~~~~~~~~~~~~~~~~~~~~~
NoParent Can not be bundled with a type constructor.
ParentIs n Can be bundled with the type constructor corresponding to
n.
FldParent See Note [Parents for record fields]
Note [Parents for record fields]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For record fields, in addition to the Name of the type constructor
(stored in par_is), we use FldParent to store the field label. This
extra information is used for identifying overloaded record fields
during renaming.
In a definition arising from a normal module (without
-XDuplicateRecordFields), par_lbl will be Nothing, meaning that the
field's label is the same as the OccName of the selector's Name. The
GlobalRdrEnv will contain an entry like this:
"x" |-> GRE x (FldParent T Nothing) LocalDef
When -XDuplicateRecordFields is enabled for the module that contains
T, the selector's Name will be mangled (see comments in FieldLabel).
Thus we store the actual field label in par_lbl, and the GlobalRdrEnv
entry looks like this:
"x" |-> GRE $sel:x:MkT (FldParent T (Just "x")) LocalDef
Note that the OccName used when adding a GRE to the environment
(greOccName) now depends on the parent field: for FldParent it is the
field label, if present, rather than the selector name.
~~
Record pattern synonym selectors are treated differently. Their parent
information is `NoParent` in the module in which they are defined. This is because
a pattern synonym `P` has no parent constructor either.
However, if `f` is bundled with a type constructor `T` then whenever `f` is
imported the parent will use the `Parent` constructor so the parent of `f` is
now `T`.
Note [Combining parents]
~~~~~~~~~~~~~~~~~~~~~~~~
With an associated type we might have
module M where
class C a where
data T a
op :: T a -> a
instance C Int where
data T Int = TInt
instance C Bool where
data T Bool = TBool
Then: C is the parent of T
T is the parent of TInt and TBool
So: in an export list
C(..) is short for C( op, T )
T(..) is short for T( TInt, TBool )
Module M exports everything, so its exports will be
AvailTC C [C,T,op]
AvailTC T [T,TInt,TBool]
On import we convert to GlobalRdrElt and then combine
those. For T that will mean we have
one GRE with Parent C
one GRE with NoParent
That's why plusParent picks the "best" case.
-}
-- | make a 'GlobalRdrEnv' where all the elements point to the same
-- Provenance (useful for "hiding" imports, or imports with no details).
gresFromAvails :: Maybe ImportSpec -> [AvailInfo] -> [GlobalRdrElt]
-- prov = Nothing => locally bound
-- Just spec => imported as described by spec
gresFromAvails prov avails
= concatMap (gresFromAvail (const prov)) avails
localGREsFromAvail :: AvailInfo -> [GlobalRdrElt]
-- Turn an Avail into a list of LocalDef GlobalRdrElts
localGREsFromAvail = gresFromAvail (const Nothing)
gresFromAvail :: (Name -> Maybe ImportSpec) -> AvailInfo -> [GlobalRdrElt]
gresFromAvail prov_fn avail
= map mk_gre (availNonFldNames avail) ++ map mk_fld_gre (availFlds avail)
where
mk_gre n
= case prov_fn n of -- Nothing => bound locally
-- Just is => imported from 'is'
Nothing -> GRE { gre_name = n, gre_par = mkParent n avail
, gre_lcl = True, gre_imp = [] }
Just is -> GRE { gre_name = n, gre_par = mkParent n avail
, gre_lcl = False, gre_imp = [is] }
mk_fld_gre (FieldLabel { flLabel = lbl, flIsOverloaded = is_overloaded
, flSelector = n })
= case prov_fn n of -- Nothing => bound locally
-- Just is => imported from 'is'
Nothing -> GRE { gre_name = n, gre_par = FldParent (availName avail) mb_lbl
, gre_lcl = True, gre_imp = [] }
Just is -> GRE { gre_name = n, gre_par = FldParent (availName avail) mb_lbl
, gre_lcl = False, gre_imp = [is] }
where
mb_lbl | is_overloaded = Just lbl
| otherwise = Nothing
greQualModName :: GlobalRdrElt -> ModuleName
-- Get a suitable module qualifier for the GRE
-- (used in mkPrintUnqualified)
-- Prerecondition: the gre_name is always External
greQualModName gre@(GRE { gre_name = name, gre_lcl = lcl, gre_imp = iss })
| lcl, Just mod <- nameModule_maybe name = moduleName mod
| (is:_) <- iss = is_as (is_decl is)
| otherwise = pprPanic "greQualModName" (ppr gre)
greUsedRdrName :: GlobalRdrElt -> RdrName
-- For imported things, return a RdrName to add to the used-RdrName
-- set, which is used to generate unused-import-decl warnings.
-- Return a Qual RdrName if poss, so that identifies the most
-- specific ImportSpec. See Trac #10890 for some good examples.
greUsedRdrName gre@GRE{ gre_name = name, gre_lcl = lcl, gre_imp = iss }
| lcl, Just mod <- nameModule_maybe name = Qual (moduleName mod) occ
| not (null iss), is <- bestImport iss = Qual (is_as (is_decl is)) occ
| otherwise = pprTrace "greUsedRdrName" (ppr gre) (Unqual occ)
where
occ = greOccName gre
greRdrNames :: GlobalRdrElt -> [RdrName]
greRdrNames gre@GRE{ gre_lcl = lcl, gre_imp = iss }
= (if lcl then [unqual] else []) ++ concatMap do_spec (map is_decl iss)
where
occ = greOccName gre
unqual = Unqual occ
do_spec decl_spec
| is_qual decl_spec = [qual]
| otherwise = [unqual,qual]
where qual = Qual (is_as decl_spec) occ
-- the SrcSpan that pprNameProvenance prints out depends on whether
-- the Name is defined locally or not: for a local definition the
-- definition site is used, otherwise the location of the import
-- declaration. We want to sort the export locations in
-- exportClashErr by this SrcSpan, we need to extract it:
greSrcSpan :: GlobalRdrElt -> SrcSpan
greSrcSpan gre@(GRE { gre_name = name, gre_lcl = lcl, gre_imp = iss } )
| lcl = nameSrcSpan name
| (is:_) <- iss = is_dloc (is_decl is)
| otherwise = pprPanic "greSrcSpan" (ppr gre)
mkParent :: Name -> AvailInfo -> Parent
mkParent _ (Avail _) = NoParent
mkParent n (AvailTC m _ _) | n == m = NoParent
| otherwise = ParentIs m
greParentName :: GlobalRdrElt -> Maybe Name
greParentName gre = case gre_par gre of
NoParent -> Nothing
ParentIs n -> Just n
FldParent n _ -> Just n
-- | Takes a list of distinct GREs and folds them
-- into AvailInfos. This is more efficient than mapping each individual
-- GRE to an AvailInfo and the folding using `plusAvail` but needs the
-- uniqueness assumption.
gresToAvailInfo :: [GlobalRdrElt] -> [AvailInfo]
gresToAvailInfo gres
= ASSERT( nub gres == gres ) nameEnvElts avail_env
where
avail_env :: NameEnv AvailInfo -- keyed by the parent
avail_env = foldl' add emptyNameEnv gres
add :: NameEnv AvailInfo -> GlobalRdrElt -> NameEnv AvailInfo
add env gre = extendNameEnv_Acc comb availFromGRE env
(fromMaybe (gre_name gre)
(greParentName gre)) gre
where
-- We want to insert the child `k` into a list of children but
-- need to maintain the invariant that the parent is first.
--
-- We also use the invariant that `k` is not already in `ns`.
insertChildIntoChildren :: Name -> [Name] -> Name -> [Name]
insertChildIntoChildren _ [] k = [k]
insertChildIntoChildren p (n:ns) k
| p == k = k:n:ns
| otherwise = n:k:ns
comb :: GlobalRdrElt -> AvailInfo -> AvailInfo
comb _ (Avail n) = Avail n -- Duplicated name
comb gre (AvailTC m ns fls) =
let n = gre_name gre
in case gre_par gre of
NoParent -> AvailTC m (n:ns) fls -- Not sure this ever happens
ParentIs {} -> AvailTC m (insertChildIntoChildren m ns n) fls
FldParent _ mb_lbl -> AvailTC m ns (mkFieldLabel n mb_lbl : fls)
availFromGRE :: GlobalRdrElt -> AvailInfo
availFromGRE (GRE { gre_name = me, gre_par = parent })
= case parent of
ParentIs p -> AvailTC p [me] []
NoParent | isTyConName me -> AvailTC me [me] []
| otherwise -> avail me
FldParent p mb_lbl -> AvailTC p [] [mkFieldLabel me mb_lbl]
mkFieldLabel :: Name -> Maybe FastString -> FieldLabel
mkFieldLabel me mb_lbl =
case mb_lbl of
Nothing -> FieldLabel { flLabel = occNameFS (nameOccName me)
, flIsOverloaded = False
, flSelector = me }
Just lbl -> FieldLabel { flLabel = lbl
, flIsOverloaded = True
, flSelector = me }
emptyGlobalRdrEnv :: GlobalRdrEnv
emptyGlobalRdrEnv = emptyOccEnv
globalRdrEnvElts :: GlobalRdrEnv -> [GlobalRdrElt]
globalRdrEnvElts env = foldOccEnv (++) [] env
instance Outputable GlobalRdrElt where
ppr gre = hang (ppr (gre_name gre) <+> ppr (gre_par gre))
2 (pprNameProvenance gre)
pprGlobalRdrEnv :: Bool -> GlobalRdrEnv -> SDoc
pprGlobalRdrEnv locals_only env
= vcat [ text "GlobalRdrEnv" <+> ppWhen locals_only (ptext (sLit "(locals only)"))
<+> lbrace
, nest 2 (vcat [ pp (remove_locals gre_list) | gre_list <- occEnvElts env ]
<+> rbrace) ]
where
remove_locals gres | locals_only = filter isLocalGRE gres
| otherwise = gres
pp [] = empty
pp gres = hang (ppr occ
<+> parens (text "unique" <+> ppr (getUnique occ))
<> colon)
2 (vcat (map ppr gres))
where
occ = nameOccName (gre_name (head gres))
lookupGlobalRdrEnv :: GlobalRdrEnv -> OccName -> [GlobalRdrElt]
lookupGlobalRdrEnv env occ_name = case lookupOccEnv env occ_name of
Nothing -> []
Just gres -> gres
greOccName :: GlobalRdrElt -> OccName
greOccName (GRE{gre_par = FldParent{par_lbl = Just lbl}}) = mkVarOccFS lbl
greOccName gre = nameOccName (gre_name gre)
lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
lookupGRE_RdrName rdr_name env
= case lookupOccEnv env (rdrNameOcc rdr_name) of
Nothing -> []
Just gres -> pickGREs rdr_name gres
lookupGRE_Name :: GlobalRdrEnv -> Name -> Maybe GlobalRdrElt
-- ^ Look for precisely this 'Name' in the environment. This tests
-- whether it is in scope, ignoring anything else that might be in
-- scope with the same 'OccName'.
lookupGRE_Name env name
= lookupGRE_Name_OccName env name (nameOccName name)
lookupGRE_FieldLabel :: GlobalRdrEnv -> FieldLabel -> Maybe GlobalRdrElt
-- ^ Look for a particular record field selector in the environment, where the
-- selector name and field label may be different: the GlobalRdrEnv is keyed on
-- the label. See Note [Parents for record fields] for why this happens.
lookupGRE_FieldLabel env fl
= lookupGRE_Name_OccName env (flSelector fl) (mkVarOccFS (flLabel fl))
lookupGRE_Name_OccName :: GlobalRdrEnv -> Name -> OccName -> Maybe GlobalRdrElt
-- ^ Look for precisely this 'Name' in the environment, but with an 'OccName'
-- that might differ from that of the 'Name'. See 'lookupGRE_FieldLabel' and
-- Note [Parents for record fields].
lookupGRE_Name_OccName env name occ
= case [ gre | gre <- lookupGlobalRdrEnv env occ
, gre_name gre == name ] of
[] -> Nothing
[gre] -> Just gre
gres -> pprPanic "lookupGRE_Name_OccName"
(ppr name $$ ppr occ $$ ppr gres)
-- See INVARIANT 1 on GlobalRdrEnv
getGRE_NameQualifier_maybes :: GlobalRdrEnv -> Name -> [Maybe [ModuleName]]
-- Returns all the qualifiers by which 'x' is in scope
-- Nothing means "the unqualified version is in scope"
-- [] means the thing is not in scope at all
getGRE_NameQualifier_maybes env name
= case lookupGRE_Name env name of
Just gre -> [qualifier_maybe gre]
Nothing -> []
where
qualifier_maybe (GRE { gre_lcl = lcl, gre_imp = iss })
| lcl = Nothing
| otherwise = Just $ map (is_as . is_decl) iss
isLocalGRE :: GlobalRdrElt -> Bool
isLocalGRE (GRE {gre_lcl = lcl }) = lcl
isRecFldGRE :: GlobalRdrElt -> Bool
isRecFldGRE (GRE {gre_par = FldParent{}}) = True
isRecFldGRE _ = False
-- Returns the field label of this GRE, if it has one
greLabel :: GlobalRdrElt -> Maybe FieldLabelString
greLabel (GRE{gre_par = FldParent{par_lbl = Just lbl}}) = Just lbl
greLabel (GRE{gre_name = n, gre_par = FldParent{}}) = Just (occNameFS (nameOccName n))
greLabel _ = Nothing
unQualOK :: GlobalRdrElt -> Bool
-- ^ Test if an unqualified version of this thing would be in scope
unQualOK (GRE {gre_lcl = lcl, gre_imp = iss })
| lcl = True
| otherwise = any unQualSpecOK iss
{- Note [GRE filtering]
~~~~~~~~~~~~~~~~~~~~~~~
(pickGREs rdr gres) takes a list of GREs which have the same OccName
as 'rdr', say "x". It does two things:
(a) filters the GREs to a subset that are in scope
* Qualified, as 'M.x' if want_qual is Qual M _
* Unqualified, as 'x' if want_unqual is Unqual _
(b) for that subset, filter the provenance field (gre_lcl and gre_imp)
to ones that brought it into scope qualified or unqualified resp.
Example:
module A ( f ) where
import qualified Foo( f )
import Baz( f )
f = undefined
Let's suppose that Foo.f and Baz.f are the same entity really, but the local
'f' is different, so there will be two GREs matching "f":
gre1: gre_lcl = True, gre_imp = []
gre2: gre_lcl = False, gre_imp = [ imported from Foo, imported from Bar ]
The use of "f" in the export list is ambiguous because it's in scope
from the local def and the import Baz(f); but *not* the import qualified Foo.
pickGREs returns two GRE
gre1: gre_lcl = True, gre_imp = []
gre2: gre_lcl = False, gre_imp = [ imported from Bar ]
Now the the "ambiguous occurrence" message can correctly report how the
ambiguity arises.
-}
pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
-- ^ Takes a list of GREs which have the right OccName 'x'
-- Pick those GREs that are are in scope
-- * Qualified, as 'M.x' if want_qual is Qual M _
-- * Unqualified, as 'x' if want_unqual is Unqual _
--
-- Return each such GRE, with its ImportSpecs filtered, to reflect
-- how it is in scope qualified or unqualified respectively.
-- See Note [GRE filtering]
pickGREs (Unqual {}) gres = mapMaybe pickUnqualGRE gres
pickGREs (Qual mod _) gres = mapMaybe (pickQualGRE mod) gres
pickGREs _ _ = [] -- I don't think this actually happens
pickUnqualGRE :: GlobalRdrElt -> Maybe GlobalRdrElt
pickUnqualGRE gre@(GRE { gre_lcl = lcl, gre_imp = iss })
| not lcl, null iss' = Nothing
| otherwise = Just (gre { gre_imp = iss' })
where
iss' = filter unQualSpecOK iss
pickQualGRE :: ModuleName -> GlobalRdrElt -> Maybe GlobalRdrElt
pickQualGRE mod gre@(GRE { gre_name = n, gre_lcl = lcl, gre_imp = iss })
| not lcl', null iss' = Nothing
| otherwise = Just (gre { gre_lcl = lcl', gre_imp = iss' })
where
iss' = filter (qualSpecOK mod) iss
lcl' = lcl && name_is_from mod n
name_is_from :: ModuleName -> Name -> Bool
name_is_from mod name = case nameModule_maybe name of
Just n_mod -> moduleName n_mod == mod
Nothing -> False
pickGREsModExp :: ModuleName -> [GlobalRdrElt] -> [(GlobalRdrElt,GlobalRdrElt)]
-- ^ Pick GREs that are in scope *both* qualified *and* unqualified
-- Return each GRE that is, as a pair
-- (qual_gre, unqual_gre)
-- These two GREs are the original GRE with imports filtered to express how
-- it is in scope qualified an unqualified respectively
--
-- Used only for the 'module M' item in export list;
-- see RnNames.exports_from_avail
pickGREsModExp mod gres = mapMaybe (pickBothGRE mod) gres
pickBothGRE :: ModuleName -> GlobalRdrElt -> Maybe (GlobalRdrElt, GlobalRdrElt)
pickBothGRE mod gre@(GRE { gre_name = n })
| isBuiltInSyntax n = Nothing
| Just gre1 <- pickQualGRE mod gre
, Just gre2 <- pickUnqualGRE gre = Just (gre1, gre2)
| otherwise = Nothing
where
-- isBuiltInSyntax filter out names for built-in syntax They
-- just clutter up the environment (esp tuples), and the
-- parser will generate Exact RdrNames for them, so the
-- cluttered envt is no use. Really, it's only useful for
-- GHC.Base and GHC.Tuple.
-- Building GlobalRdrEnvs
plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv
plusGlobalRdrEnv env1 env2 = plusOccEnv_C (foldr insertGRE) env1 env2
mkGlobalRdrEnv :: [GlobalRdrElt] -> GlobalRdrEnv
mkGlobalRdrEnv gres
= foldr add emptyGlobalRdrEnv gres
where
add gre env = extendOccEnv_Acc insertGRE singleton env
(greOccName gre)
gre
insertGRE :: GlobalRdrElt -> [GlobalRdrElt] -> [GlobalRdrElt]
insertGRE new_g [] = [new_g]
insertGRE new_g (old_g : old_gs)
| gre_name new_g == gre_name old_g
= new_g `plusGRE` old_g : old_gs
| otherwise
= old_g : insertGRE new_g old_gs
plusGRE :: GlobalRdrElt -> GlobalRdrElt -> GlobalRdrElt
-- Used when the gre_name fields match
plusGRE g1 g2
= GRE { gre_name = gre_name g1
, gre_lcl = gre_lcl g1 || gre_lcl g2
, gre_imp = gre_imp g1 ++ gre_imp g2
, gre_par = gre_par g1 `plusParent` gre_par g2 }
transformGREs :: (GlobalRdrElt -> GlobalRdrElt)
-> [OccName]
-> GlobalRdrEnv -> GlobalRdrEnv
-- ^ Apply a transformation function to the GREs for these OccNames
transformGREs trans_gre occs rdr_env
= foldr trans rdr_env occs
where
trans occ env
= case lookupOccEnv env occ of
Just gres -> extendOccEnv env occ (map trans_gre gres)
Nothing -> env
extendGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrElt -> GlobalRdrEnv
extendGlobalRdrEnv env gre
= extendOccEnv_Acc insertGRE singleton env
(greOccName gre) gre
shadowNames :: GlobalRdrEnv -> [Name] -> GlobalRdrEnv
shadowNames = foldl shadowName
{- Note [GlobalRdrEnv shadowing]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before adding new names to the GlobalRdrEnv we nuke some existing entries;
this is "shadowing". The actual work is done by RdrEnv.shadowNames.
There are two reasons for shadowing:
* The GHCi REPL
- Ids bought into scope on the command line (eg let x = True) have
External Names, like Ghci4.x. We want a new binding for 'x' (say)
to override the existing binding for 'x'.
See Note [Interactively-bound Ids in GHCi] in HscTypes
- Data types also have Extenal Names, like Ghci4.T; but we still want
'T' to mean the newly-declared 'T', not an old one.
* Nested Template Haskell declaration brackets
See Note [Top-level Names in Template Haskell decl quotes] in RnNames
Consider a TH decl quote:
module M where
f x = h [d| f = 3 |]
We must shadow the outer declaration of 'f', else we'll get a
complaint when extending the GlobalRdrEnv, saying that there are two
bindings for 'f'. There are several tricky points:
- This shadowing applies even if the binding for 'f' is in a
where-clause, and hence is in the *local* RdrEnv not the *global*
RdrEnv. This is done in lcl_env_TH in extendGlobalRdrEnvRn.
- The External Name M.f from the enclosing module must certainly
still be available. So we don't nuke it entirely; we just make
it seem like qualified import.
- We only shadow *External* names (which come from the main module),
or from earlier GHCi commands. Do not shadow *Internal* names
because in the bracket
[d| class C a where f :: a
f = 4 |]
rnSrcDecls will first call extendGlobalRdrEnvRn with C[f] from the
class decl, and *separately* extend the envt with the value binding.
At that stage, the class op 'f' will have an Internal name.
-}
shadowName :: GlobalRdrEnv -> Name -> GlobalRdrEnv
-- Remove certain old GREs that share the same OccName as this new Name.
-- See Note [GlobalRdrEnv shadowing] for details
shadowName env name
= alterOccEnv (fmap alter_fn) env (nameOccName name)
where
alter_fn :: [GlobalRdrElt] -> [GlobalRdrElt]
alter_fn gres = mapMaybe (shadow_with name) gres
shadow_with :: Name -> GlobalRdrElt -> Maybe GlobalRdrElt
shadow_with new_name
old_gre@(GRE { gre_name = old_name, gre_lcl = lcl, gre_imp = iss })
= case nameModule_maybe old_name of
Nothing -> Just old_gre -- Old name is Internal; do not shadow
Just old_mod
| Just new_mod <- nameModule_maybe new_name
, new_mod == old_mod -- Old name same as new name; shadow completely
-> Nothing
| null iss' -- Nothing remains
-> Nothing
| otherwise
-> Just (old_gre { gre_lcl = False, gre_imp = iss' })
where
iss' = lcl_imp ++ mapMaybe (shadow_is new_name) iss
lcl_imp | lcl = [mk_fake_imp_spec old_name old_mod]
| otherwise = []
mk_fake_imp_spec old_name old_mod -- Urgh!
= ImpSpec id_spec ImpAll
where
old_mod_name = moduleName old_mod
id_spec = ImpDeclSpec { is_mod = old_mod_name
, is_as = old_mod_name
, is_qual = True
, is_dloc = nameSrcSpan old_name }
shadow_is :: Name -> ImportSpec -> Maybe ImportSpec
shadow_is new_name is@(ImpSpec { is_decl = id_spec })
| Just new_mod <- nameModule_maybe new_name
, is_as id_spec == moduleName new_mod
= Nothing -- Shadow both qualified and unqualified
| otherwise -- Shadow unqualified only
= Just (is { is_decl = id_spec { is_qual = True } })
{-
************************************************************************
* *
ImportSpec
* *
************************************************************************
-}
-- | Import Specification
--
-- The 'ImportSpec' of something says how it came to be imported
-- It's quite elaborate so that we can give accurate unused-name warnings.
data ImportSpec = ImpSpec { is_decl :: ImpDeclSpec,
is_item :: ImpItemSpec }
deriving( Eq, Ord, Data )
-- | Import Declaration Specification
--
-- Describes a particular import declaration and is
-- shared among all the 'Provenance's for that decl
data ImpDeclSpec
= ImpDeclSpec {
is_mod :: ModuleName, -- ^ Module imported, e.g. @import Muggle@
-- Note the @Muggle@ may well not be
-- the defining module for this thing!
-- TODO: either should be Module, or there
-- should be a Maybe UnitId here too.
is_as :: ModuleName, -- ^ Import alias, e.g. from @as M@ (or @Muggle@ if there is no @as@ clause)
is_qual :: Bool, -- ^ Was this import qualified?
is_dloc :: SrcSpan -- ^ The location of the entire import declaration
} deriving Data
-- | Import Item Specification
--
-- Describes import info a particular Name
data ImpItemSpec
= ImpAll -- ^ The import had no import list,
-- or had a hiding list
| ImpSome {
is_explicit :: Bool,
is_iloc :: SrcSpan -- Location of the import item
} -- ^ The import had an import list.
-- The 'is_explicit' field is @True@ iff the thing was named
-- /explicitly/ in the import specs rather
-- than being imported as part of a "..." group. Consider:
--
-- > import C( T(..) )
--
-- Here the constructors of @T@ are not named explicitly;
-- only @T@ is named explicitly.
deriving Data
instance Eq ImpDeclSpec where
p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
instance Ord ImpDeclSpec where
compare is1 is2 = (is_mod is1 `compare` is_mod is2) `thenCmp`
(is_dloc is1 `compare` is_dloc is2)
instance Eq ImpItemSpec where
p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
instance Ord ImpItemSpec where
compare is1 is2 =
case (is1, is2) of
(ImpAll, ImpAll) -> EQ
(ImpAll, _) -> GT
(_, ImpAll) -> LT
(ImpSome _ l1, ImpSome _ l2) -> l1 `compare` l2
bestImport :: [ImportSpec] -> ImportSpec
-- Given a non-empty bunch of ImportSpecs, return the one that
-- imported the item most specifically (e.g. by name), using
-- textually-first as a tie breaker. This is used when reporting
-- redundant imports
bestImport iss
= case sortBy best iss of
(is:_) -> is
[] -> pprPanic "bestImport" (ppr iss)
where
best :: ImportSpec -> ImportSpec -> Ordering
-- Less means better
best (ImpSpec { is_item = item1, is_decl = d1 })
(ImpSpec { is_item = item2, is_decl = d2 })
= best_item item1 item2 `thenCmp` (is_dloc d1 `compare` is_dloc d2)
best_item :: ImpItemSpec -> ImpItemSpec -> Ordering
best_item ImpAll ImpAll = EQ
best_item ImpAll (ImpSome {}) = GT
best_item (ImpSome {}) ImpAll = LT
best_item (ImpSome { is_explicit = e1 })
(ImpSome { is_explicit = e2 }) = e2 `compare` e1
-- False < True, so if e1 is explicit and e2 is not, we get LT
unQualSpecOK :: ImportSpec -> Bool
-- ^ Is in scope unqualified?
unQualSpecOK is = not (is_qual (is_decl is))
qualSpecOK :: ModuleName -> ImportSpec -> Bool
-- ^ Is in scope qualified with the given module?
qualSpecOK mod is = mod == is_as (is_decl is)
importSpecLoc :: ImportSpec -> SrcSpan
importSpecLoc (ImpSpec decl ImpAll) = is_dloc decl
importSpecLoc (ImpSpec _ item) = is_iloc item
importSpecModule :: ImportSpec -> ModuleName
importSpecModule is = is_mod (is_decl is)
isExplicitItem :: ImpItemSpec -> Bool
isExplicitItem ImpAll = False
isExplicitItem (ImpSome {is_explicit = exp}) = exp
pprNameProvenance :: GlobalRdrElt -> SDoc
-- ^ Print out one place where the name was define/imported
-- (With -dppr-debug, print them all)
pprNameProvenance (GRE { gre_name = name, gre_lcl = lcl, gre_imp = iss })
= sdocWithPprDebug $ \dbg -> if dbg
then vcat pp_provs
else head pp_provs
where
pp_provs = pp_lcl ++ map pp_is iss
pp_lcl = if lcl then [text "defined at" <+> ppr (nameSrcLoc name)]
else []
pp_is is = sep [ppr is, ppr_defn_site is name]
-- If we know the exact definition point (which we may do with GHCi)
-- then show that too. But not if it's just "imported from X".
ppr_defn_site :: ImportSpec -> Name -> SDoc
ppr_defn_site imp_spec name
| same_module && not (isGoodSrcSpan loc)
= empty -- Nothing interesting to say
| otherwise
= parens $ hang (text "and originally defined" <+> pp_mod)
2 (pprLoc loc)
where
loc = nameSrcSpan name
defining_mod = ASSERT2( isExternalName name, ppr name ) nameModule name
same_module = importSpecModule imp_spec == moduleName defining_mod
pp_mod | same_module = empty
| otherwise = text "in" <+> quotes (ppr defining_mod)
instance Outputable ImportSpec where
ppr imp_spec
= text "imported" <+> qual
<+> text "from" <+> quotes (ppr (importSpecModule imp_spec))
<+> pprLoc (importSpecLoc imp_spec)
where
qual | is_qual (is_decl imp_spec) = text "qualified"
| otherwise = empty
pprLoc :: SrcSpan -> SDoc
pprLoc (RealSrcSpan s) = text "at" <+> ppr s
pprLoc (UnhelpfulSpan {}) = empty