[Git][ghc/ghc][master] Turn "ambiguous import" error into a panic
Marge Bot (@marge-bot)
gitlab at gitlab.haskell.org
Mon May 15 15:27:19 UTC 2023
Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC
Commits:
5b9e9300 by sheaf at 2023-05-15T11:26:59-04:00
Turn "ambiguous import" error into a panic
This error should never occur, as a lookup of a type or data constructor
should never be ambiguous. This is because a single module cannot export
multiple Names with the same OccName, as per item (1) of
Note [Exporting duplicate declarations] in GHC.Tc.Gen.Export.
This code path was intended to handle duplicate record fields, but the
rest of the code had since been refactored to handle those in a
different way.
We also remove the AmbiguousImport constructor of IELookupError, as
it is no longer used.
Fixes #23302
- - - - -
1 changed file:
- compiler/GHC/Rename/Names.hs
Changes:
=====================================
compiler/GHC/Rename/Names.hs
=====================================
@@ -1196,27 +1196,42 @@ filterImports hsc_env iface decl_spec (Just (want_hiding, L l import_items))
hiding_spec = ImpSpec { is_decl = decl_spec, is_item = ImpAll }
imp_occ_env = mkImportOccEnv hsc_env decl_spec all_avails
- -- Look up a RdrName used in an import, failing if it is ambiguous
- -- (e.g. because it refers to multiple record fields)
- lookup_name :: IE GhcPs -> RdrName -> IELookupM ImpOccItem
- lookup_name ie rdr = do
- xs <- lookup_names ie rdr
- case xs of
- [cax] -> return cax
- _ -> failLookupWith (AmbiguousImport rdr (map imp_item xs))
+ -- Look up a parent (type constructor, class or data constructor)
+ -- in an import.
+ lookup_parent :: IE GhcPs -> RdrName -> IELookupM ImpOccItem
+ lookup_parent ie rdr =
+ assertPpr (not $ isVarNameSpace ns)
+ (vcat [ text "filterImports lookup_parent: unexpected variable"
+ , text "rdr:" <+> ppr rdr
+ , text "namespace:" <+> pprNameSpace ns ]) $
+ do { xs <- lookup_names ie rdr
+ ; case xs of
+ cax :| [] -> return cax
+ _ -> pprPanic "filter_imports lookup_parent ambiguous" $
+ vcat [ text "rdr:" <+> ppr rdr
+ , text "lookups:" <+> ppr (fmap imp_item xs) ] }
+ -- Looking up non-variables is always unambiguous,
+ -- as there can be at most one corresponding item
+ -- in the imp_occ_env.
+ -- See item (1) of Note [Exporting duplicate declarations]
+ -- in GHC.Tc.Gen.Export.
+ where
+ occ = rdrNameOcc rdr
+ ns = occNameSpace occ
-- Look up a RdrName used in an import, returning multiple values if there
-- are several fields with the same name exposed by the module
- lookup_names :: IE GhcPs -> RdrName -> IELookupM [ImpOccItem]
+ lookup_names :: IE GhcPs -> RdrName -> IELookupM (NonEmpty ImpOccItem)
lookup_names ie rdr
| isQual rdr
= failLookupWith (QualImportError rdr)
- | null lookups
- = failLookupWith (BadImport ie BadImportIsParent)
| otherwise
- = return $ concatMap nonDetNameEnvElts lookups
+ = case lookups of
+ [] -> failLookupWith (BadImport ie BadImportIsParent)
+ item:items -> return $ item :| items
where
- lookups = lookupOccEnv_WithFields imp_occ_env (rdrNameOcc rdr)
+ lookups = concatMap nonDetNameEnvElts
+ $ lookupOccEnv_WithFields imp_occ_env (rdrNameOcc rdr)
lookup_lie :: LIE GhcPs -> TcRn [(LIE GhcRn, [GlobalRdrElt])]
lookup_lie (L loc ieRdr)
@@ -1248,10 +1263,9 @@ filterImports hsc_env iface decl_spec (Just (want_hiding, L l import_items))
Succeeded a -> return (Just a)
lookup_err_msg err = case err of
- BadImport ie sub -> badImportItemErr iface decl_spec ie sub all_avails
- IllegalImport -> pure ImportLookupIllegal
+ BadImport ie sub -> badImportItemErr iface decl_spec ie sub all_avails
+ IllegalImport -> pure ImportLookupIllegal
QualImportError rdr -> pure (ImportLookupQualified rdr)
- AmbiguousImport rdr xs -> pure (ImportLookupAmbiguous rdr xs)
-- For each import item, we convert its RdrNames to Names,
-- and at the same time compute all the GlobalRdrElt corresponding
@@ -1269,12 +1283,12 @@ filterImports hsc_env iface decl_spec (Just (want_hiding, L l import_items))
-- See Note [Importing DuplicateRecordFields]
xs <- lookup_names ie (ieWrappedName n)
return ( [ (IEVar noExtField (L l (replaceWrappedName n name)), [gre])
- | ImpOccItem { imp_item = gre } <- xs
+ | ImpOccItem { imp_item = gre } <- NE.toList xs
, let name = greName gre ]
, [] )
IEThingAll _ (L l tc) -> do
- ImpOccItem gre child_gres _ <- lookup_name ie $ ieWrappedName tc
+ ImpOccItem gre child_gres _ <- lookup_parent ie $ ieWrappedName tc
let name = greName gre
warns
@@ -1299,19 +1313,19 @@ filterImports hsc_env iface decl_spec (Just (want_hiding, L l import_items))
-- Here the 'C' can be a data constructor
-- *or* a type/class, or even both
-> let tc = ieWrappedName tc'
- tc_name = lookup_name ie tc
- dc_name = lookup_name ie (setRdrNameSpace tc srcDataName)
+ tc_name = lookup_parent ie tc
+ dc_name = lookup_parent ie (setRdrNameSpace tc srcDataName)
in
case catIELookupM [ tc_name, dc_name ] of
[] -> failLookupWith (BadImport ie BadImportIsParent)
names -> return ([mkIEThingAbs tc' l (imp_item name) | name <- names], [])
| otherwise
- -> do ImpOccItem { imp_item = gre } <- lookup_name ie (ieWrappedName tc')
+ -> do ImpOccItem { imp_item = gre } <- lookup_parent ie (ieWrappedName tc')
return ([mkIEThingAbs tc' l gre], [])
IEThingWith xt ltc@(L l rdr_tc) wc rdr_ns -> do
ImpOccItem { imp_item = gre, imp_bundled = subnames }
- <- lookup_name (IEThingAbs noAnn ltc) (ieWrappedName rdr_tc)
+ <- lookup_parent (IEThingAbs noAnn ltc) (ieWrappedName rdr_tc)
let name = greName gre
-- Look up the children in the sub-names of the parent
@@ -1358,7 +1372,6 @@ data IELookupError
= QualImportError RdrName
| BadImport (IE GhcPs) BadImportIsSubordinate
| IllegalImport
- | AmbiguousImport RdrName [GlobalRdrElt] -- e.g. a duplicated field name as a top-level import
failLookupWith :: IELookupError -> IELookupM a
failLookupWith err = Failed err
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/5b9e9300c3766a3ef4b19a2274ecc6e8c56fe86c
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/5b9e9300c3766a3ef4b19a2274ecc6e8c56fe86c
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