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%
% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\begin{code}
{-# LANGUAGE 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, setRdrNameSpace,
isRdrDataCon, isRdrTyVar, isRdrTc, isQual, isQual_maybe, isUnqual,
isOrig, isOrig_maybe, isExact, isExact_maybe, isSrcRdrName,
-- ** Printing
showRdrName,
-- * Local mapping of 'RdrName' to 'Name.Name'
LocalRdrEnv, emptyLocalRdrEnv, extendLocalRdrEnv, extendLocalRdrEnvList,
lookupLocalRdrEnv, lookupLocalRdrOcc, elemLocalRdrEnv,
-- * Global mapping of 'RdrName' to 'GlobalRdrElt's
GlobalRdrEnv, emptyGlobalRdrEnv, mkGlobalRdrEnv, plusGlobalRdrEnv,
lookupGlobalRdrEnv, extendGlobalRdrEnv,
pprGlobalRdrEnv, globalRdrEnvElts,
lookupGRE_RdrName, lookupGRE_Name, getGRE_NameQualifier_maybes,
transformGREs, findLocalDupsRdrEnv, pickGREs,
-- ** Global 'RdrName' mapping elements: 'GlobalRdrElt', 'Provenance', 'ImportSpec'
GlobalRdrElt(..), isLocalGRE, unQualOK, qualSpecOK, unQualSpecOK,
Provenance(..), pprNameProvenance,
Parent(..),
ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..),
importSpecLoc, importSpecModule, isExplicitItem
) where
#include "HsVersions.h"
import Module
import Name
import Maybes
import SrcLoc
import FastString
import Outputable
import Unique
import Util
import StaticFlags( opt_PprStyle_Debug )
import Data.Data
\end{code}
%************************************************************************
%* *
\subsection{The main data type}
%* *
%************************************************************************
\begin{code}
-- | Do not use the data constructors of RdrName directly: prefer the family
-- of functions that creates them, such as 'mkRdrUnqual'
data RdrName
= Unqual OccName
-- ^ Used for ordinary, unqualified occurrences, e.g. @x@, @y@ or @Foo@.
-- Create such a 'RdrName' with 'mkRdrUnqual'
| Qual ModuleName OccName
-- ^ 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
-- ^ 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
-- ^ 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, Typeable)
\end{code}
%************************************************************************
%* *
\subsection{Simple functions}
%* *
%************************************************************************
\begin{code}
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
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 = ASSERT( isExternalName n )
Orig (nameModule n)
(setOccNameSpace ns (nameOccName n))
\end{code}
\begin{code}
-- 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)
\end{code}
\begin{code}
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
\end{code}
%************************************************************************
%* *
\subsection{Instances}
%* *
%************************************************************************
\begin{code}
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 name <> ppr occ)
where name = mkExternalName (mkUniqueGrimily 0) mod occ noSrcSpan
-- Note [Outputable Orig RdrName] in HscTypes
instance OutputableBndr RdrName where
pprBndr _ n
| isTvOcc (rdrNameOcc n) = char '@' <+> ppr n
| otherwise = ppr n
showRdrName :: RdrName -> String
showRdrName r = showSDoc (ppr r)
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
\end{code}
%************************************************************************
%* *
LocalRdrEnv
%* *
%************************************************************************
\begin{code}
-- | 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
type LocalRdrEnv = OccEnv Name
emptyLocalRdrEnv :: LocalRdrEnv
emptyLocalRdrEnv = emptyOccEnv
extendLocalRdrEnv :: LocalRdrEnv -> Name -> LocalRdrEnv
extendLocalRdrEnv env name
= extendOccEnv env (nameOccName name) name
extendLocalRdrEnvList :: LocalRdrEnv -> [Name] -> LocalRdrEnv
extendLocalRdrEnvList env names
= extendOccEnvList env [(nameOccName n, n) | n <- names]
lookupLocalRdrEnv :: LocalRdrEnv -> RdrName -> Maybe Name
lookupLocalRdrEnv env (Unqual occ) = lookupOccEnv env occ
lookupLocalRdrEnv _ _ = Nothing
lookupLocalRdrOcc :: LocalRdrEnv -> OccName -> Maybe Name
lookupLocalRdrOcc env occ = lookupOccEnv env occ
elemLocalRdrEnv :: RdrName -> LocalRdrEnv -> Bool
elemLocalRdrEnv rdr_name env
| isUnqual rdr_name = rdrNameOcc rdr_name `elemOccEnv` env
| otherwise = False
\end{code}
%************************************************************************
%* *
GlobalRdrEnv
%* *
%************************************************************************
\begin{code}
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: All the members of the list have distinct
-- 'gre_name' fields; that is, no duplicate Names
--
-- INVARIANT: 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]
-- | An element of the 'GlobalRdrEnv'
data GlobalRdrElt
= GRE { gre_name :: Name,
gre_par :: Parent,
gre_prov :: Provenance -- ^ Why it's in scope
}
-- | The children of a Name are the things that are abbreviated by the ".."
-- notation in export lists. See Note [Parents]
data Parent = NoParent | ParentIs Name
deriving (Eq)
{- 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
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 the 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.
-}
instance Outputable Parent where
ppr NoParent = empty
ppr (ParentIs n) = ptext (sLit "parent:") <> ppr n
plusParent :: Parent -> Parent -> Parent
-- See Note [Combining parents]
plusParent (ParentIs n) p2 = hasParent n p2
plusParent p1 (ParentIs n) = hasParent n p1
plusParent _ _ = NoParent
hasParent :: Name -> Parent -> Parent
#ifdef DEBUG
hasParent n (ParentIs n')
| n /= n' = pprPanic "hasParent" (ppr n <+> ppr n') -- Parents should agree
#endif
hasParent n _ = ParentIs n
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 :: GlobalRdrEnv -> SDoc
pprGlobalRdrEnv env
= vcat (map pp (occEnvElts env))
where
pp gres = ppr (nameOccName (gre_name (head gres))) <> colon <+>
vcat (map ppr gres)
\end{code}
\begin{code}
lookupGlobalRdrEnv :: GlobalRdrEnv -> OccName -> [GlobalRdrElt]
lookupGlobalRdrEnv env occ_name = case lookupOccEnv env occ_name of
Nothing -> []
Just gres -> gres
extendGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrElt -> GlobalRdrEnv
extendGlobalRdrEnv env gre = extendOccEnv_Acc (:) singleton env occ gre
where
occ = 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 -> [GlobalRdrElt]
lookupGRE_Name env name
= [ gre | gre <- lookupGlobalRdrEnv env (nameOccName name),
gre_name gre == name ]
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
= map (qualifier_maybe . gre_prov) . lookupGRE_Name env
where
qualifier_maybe LocalDef = Nothing
qualifier_maybe (Imported iss) = Just $ map (is_as . is_decl) iss
pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
-- ^ Take a list of GREs which have the right OccName
-- Pick those GREs that are suitable for this RdrName
-- And for those, keep only only the Provenances that are suitable
--
-- Consider:
--
-- @
-- 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.
-- The export of @f@ is ambiguous because it's in scope from the local def
-- and the import. The lookup of @Unqual f@ should return a GRE for
-- the locally-defined @f@, and a GRE for the imported @f@, with a /single/
-- provenance, namely the one for @Baz(f)@.
pickGREs rdr_name gres
= mapCatMaybes pick gres
where
rdr_is_unqual = isUnqual rdr_name
rdr_is_qual = isQual_maybe rdr_name
pick :: GlobalRdrElt -> Maybe GlobalRdrElt
pick gre@(GRE {gre_prov = LocalDef, gre_name = n}) -- Local def
| rdr_is_unqual = Just gre
| Just (mod,_) <- rdr_is_qual -- Qualified name
, Just n_mod <- nameModule_maybe n -- Binder is External
, mod == moduleName n_mod = Just gre
| otherwise = Nothing
pick gre@(GRE {gre_prov = Imported [is]}) -- Single import (efficiency)
| rdr_is_unqual,
not (is_qual (is_decl is)) = Just gre
| Just (mod,_) <- rdr_is_qual,
mod == is_as (is_decl is) = Just gre
| otherwise = Nothing
pick gre@(GRE {gre_prov = Imported is}) -- Multiple import
| null filtered_is = Nothing
| otherwise = Just (gre {gre_prov = Imported filtered_is})
where
filtered_is | rdr_is_unqual
= filter (not . is_qual . is_decl) is
| Just (mod,_) <- rdr_is_qual
= filter ((== mod) . is_as . is_decl) is
| otherwise
= []
isLocalGRE :: GlobalRdrElt -> Bool
isLocalGRE (GRE {gre_prov = LocalDef}) = True
isLocalGRE _ = False
unQualOK :: GlobalRdrElt -> Bool
-- ^ Test if an unqualifed version of this thing would be in scope
unQualOK (GRE {gre_prov = LocalDef}) = True
unQualOK (GRE {gre_prov = Imported is}) = any unQualSpecOK is
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
(nameOccName (gre_name gre))
gre
findLocalDupsRdrEnv :: GlobalRdrEnv -> [OccName] -> (GlobalRdrEnv, [[Name]])
-- ^ For each 'OccName', see if there are multiple local definitions
-- for it. If so, remove all but one (to suppress subsequent error messages)
-- and return a list of the duplicate bindings
findLocalDupsRdrEnv rdr_env occs
= go rdr_env [] occs
where
go rdr_env dups [] = (rdr_env, dups)
go rdr_env dups (occ:occs)
= case filter isLocalGRE gres of
[] -> WARN( True, ppr occ <+> ppr rdr_env )
go rdr_env dups occs -- Weird! No binding for occ
[_] -> go rdr_env dups occs -- The common case
dup_gres -> go (extendOccEnv rdr_env occ (head dup_gres : nonlocal_gres))
(map gre_name dup_gres : dups)
occs
where
gres = lookupOccEnv rdr_env occ `orElse` []
nonlocal_gres = filterOut isLocalGRE gres
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_prov = gre_prov g1 `plusProv` gre_prov 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
\end{code}
%************************************************************************
%* *
Provenance
%* *
%************************************************************************
\begin{code}
-- | The 'Provenance' of something says how it came to be in scope.
-- It's quite elaborate so that we can give accurate unused-name warnings.
data Provenance
= LocalDef -- ^ The thing was defined locally
| Imported
[ImportSpec] -- ^ The thing was imported.
--
-- INVARIANT: the list of 'ImportSpec' is non-empty
data ImportSpec = ImpSpec { is_decl :: ImpDeclSpec,
is_item :: ImpItemSpec }
deriving( Eq, Ord )
-- | 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 PackageId 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
}
-- | 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.
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
-- Note [Comparing provenance]
-- Comparison of provenance is just used for grouping
-- error messages (in RnEnv.warnUnusedBinds)
instance Eq Provenance where
p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
instance Eq ImpDeclSpec where
p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
instance Eq ImpItemSpec where
p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
instance Ord Provenance where
compare LocalDef LocalDef = EQ
compare LocalDef (Imported _) = LT
compare (Imported _ ) LocalDef = GT
compare (Imported is1) (Imported is2) = compare (head is1)
{- See Note [Comparing provenance] -} (head is2)
instance Ord ImpDeclSpec where
compare is1 is2 = (is_mod is1 `compare` is_mod is2) `thenCmp`
(is_dloc is1 `compare` is_dloc is2)
instance Ord ImpItemSpec where
compare is1 is2 = is_iloc is1 `compare` is_iloc is2
\end{code}
\begin{code}
plusProv :: Provenance -> Provenance -> Provenance
-- Choose LocalDef over Imported
-- There is an obscure bug lurking here; in the presence
-- of recursive modules, something can be imported *and* locally
-- defined, and one might refer to it with a qualified name from
-- the import -- but I'm going to ignore that because it makes
-- the isLocalGRE predicate so much nicer this way
plusProv LocalDef LocalDef = panic "plusProv"
plusProv LocalDef _ = LocalDef
plusProv _ LocalDef = LocalDef
plusProv (Imported is1) (Imported is2) = Imported (is1++is2)
pprNameProvenance :: GlobalRdrElt -> SDoc
-- ^ Print out the place where the name was imported
pprNameProvenance (GRE {gre_name = name, gre_prov = LocalDef})
= ptext (sLit "defined at") <+> ppr (nameSrcLoc name)
pprNameProvenance (GRE {gre_name = name, gre_prov = Imported whys})
= case whys of
(why:_) | opt_PprStyle_Debug -> vcat (map pp_why whys)
| otherwise -> pp_why why
[] -> panic "pprNameProvenance"
where
pp_why why = sep [ppr why, ppr_defn_site why 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 (ptext (sLit "and originally defined") <+> pp_mod)
2 (pprLoc loc)
where
loc = nameSrcSpan name
defining_mod = nameModule name
same_module = importSpecModule imp_spec == moduleName defining_mod
pp_mod | same_module = empty
| otherwise = ptext (sLit "in") <+> quotes (ppr defining_mod)
instance Outputable ImportSpec where
ppr imp_spec
= ptext (sLit "imported") <+> qual
<+> ptext (sLit "from") <+> quotes (ppr (importSpecModule imp_spec))
<+> pprLoc (importSpecLoc imp_spec)
where
qual | is_qual (is_decl imp_spec) = ptext (sLit "qualified")
| otherwise = empty
pprLoc :: SrcSpan -> SDoc
pprLoc (RealSrcSpan s) = ptext (sLit "at") <+> ppr s
pprLoc (UnhelpfulSpan {}) = empty
\end{code}
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