--- lookupLocatedSigOccRn is used for type signatures and pragmas
--- Is this valid?
--- module A
--- import M( f )
--- f :: Int -> Int
--- f x = x
--- It's clear that the 'f' in the signature must refer to A.f
--- The Haskell98 report does not stipulate this, but it will!
--- So we must treat the 'f' in the signature in the same way
--- as the binding occurrence of 'f', using lookupBndrRn
-lookupLocatedSigOccRn :: Located RdrName -> RnM (Located Name)
-lookupLocatedSigOccRn = lookupLocatedBndrRn
-
--- lookupInstDeclBndr is used for the binders in an
--- instance declaration. Here we use the class name to
--- disambiguate.
-
-lookupLocatedInstDeclBndr :: Name -> Located RdrName -> RnM (Located Name)
-lookupLocatedInstDeclBndr cls = wrapLocM (lookupInstDeclBndr cls)
-
-lookupInstDeclBndr :: Name -> RdrName -> RnM Name
-lookupInstDeclBndr cls_name rdr_name
+
+-----------------------------------------------
+lookupInstDeclBndr :: Name -> Located RdrName -> RnM (Located Name)
+-- This is called on the method name on the left-hand side of an
+-- instance declaration binding. eg. instance Functor T where
+-- fmap = ...
+-- ^^^^ called on this
+-- Regardless of how many unqualified fmaps are in scope, we want
+-- the one that comes from the Functor class.
+--
+-- Furthermore, note that we take no account of whether the
+-- name is only in scope qualified. I.e. even if method op is
+-- in scope as M.op, we still allow plain 'op' on the LHS of
+-- an instance decl
+lookupInstDeclBndr cls rdr = lookup_located_sub_bndr is_op doc rdr
+ where
+ doc = ptext (sLit "method of class") <+> quotes (ppr cls)
+ is_op (GRE {gre_par = ParentIs n}) = n == cls
+ is_op _ = False
+
+-----------------------------------------------
+lookupRecordBndr :: Maybe (Located Name) -> Located RdrName -> RnM (Located Name)
+-- Used for record construction and pattern matching
+-- When the -fdisambiguate-record-fields flag is on, take account of the
+-- constructor name to disambiguate which field to use; it's just the
+-- same as for instance decls
+lookupRecordBndr Nothing rdr_name
+ = lookupLocatedGlobalOccRn rdr_name
+lookupRecordBndr (Just (L _ data_con)) rdr_name
+ = do { flag_on <- doptM Opt_DisambiguateRecordFields
+ ; if not flag_on
+ then lookupLocatedGlobalOccRn rdr_name
+ else do {
+ fields <- lookupConstructorFields data_con
+ ; let is_field gre = gre_name gre `elem` fields
+ ; lookup_located_sub_bndr is_field doc rdr_name
+ }}
+ where
+ doc = ptext (sLit "field of constructor") <+> quotes (ppr data_con)
+
+
+lookupConstructorFields :: Name -> RnM [Name]
+-- Look up the fields of a given constructor
+-- * For constructors from this module, use the record field env,
+-- which is itself gathered from the (as yet un-typechecked)
+-- data type decls
+--
+-- * For constructors from imported modules, use the *type* environment
+-- since imported modles are already compiled, the info is conveniently
+-- right there
+
+lookupConstructorFields con_name
+ = do { this_mod <- getModule
+ ; if nameIsLocalOrFrom this_mod con_name then
+ do { field_env <- getRecFieldEnv
+ ; return (lookupNameEnv field_env con_name `orElse` []) }
+ else
+ do { con <- tcLookupDataCon con_name
+ ; return (dataConFieldLabels con) } }
+
+-----------------------------------------------
+lookup_located_sub_bndr :: (GlobalRdrElt -> Bool)
+ -> SDoc -> Located RdrName
+ -> RnM (Located Name)
+lookup_located_sub_bndr is_good doc rdr_name
+ = wrapLocM (lookup_sub_bndr is_good doc) rdr_name
+
+lookup_sub_bndr :: (GlobalRdrElt -> Bool) -> SDoc -> RdrName -> RnM Name
+lookup_sub_bndr is_good doc rdr_name