diff options
Diffstat (limited to 'compiler/rename/RnNames.lhs')
| -rw-r--r-- | compiler/rename/RnNames.lhs | 80 |
1 files changed, 13 insertions, 67 deletions
diff --git a/compiler/rename/RnNames.lhs b/compiler/rename/RnNames.lhs index b1a61db2a2..553c3ef81a 100644 --- a/compiler/rename/RnNames.lhs +++ b/compiler/rename/RnNames.lhs @@ -7,7 +7,7 @@ module RnNames ( rnImports, getLocalNonValBinders, rnExports, extendGlobalRdrEnvRn, - gresFromAvails, lookupTcdName, + gresFromAvails, reportUnusedNames, finishWarnings, ) where @@ -528,6 +528,18 @@ getLocalNonValBinders fixity_env ; names@(main_name : _) <- mapM newTopSrcBinder bndrs ; return (AvailTC main_name names) } + new_assoc :: LInstDecl RdrName -> RnM [AvailInfo] + new_assoc (L _ (FamInstDecl d)) + = do { avail <- new_ti Nothing d + ; return [avail] } + new_assoc (L _ (ClsInstDecl inst_ty _ _ ats)) + | Just (_, _, L loc cls_rdr, _) <- splitLHsInstDeclTy_maybe inst_ty + = do { cls_nm <- setSrcSpan loc $ lookupGlobalOccRn cls_rdr + ; mapM (new_ti (Just cls_nm) . unLoc) ats } + | otherwise + = return [] -- Do not crash on ill-formed instances + -- Eg instance !Show Int Trac #3811c + new_ti :: Maybe Name -> FamInstDecl RdrName -> RnM AvailInfo new_ti mb_cls ti_decl -- ONLY for type/data instances = ASSERT( isFamInstDecl ti_decl ) @@ -535,37 +547,6 @@ getLocalNonValBinders fixity_env ; sub_names <- mapM newTopSrcBinder (hsTyClDeclBinders ti_decl) ; return (AvailTC (unLoc main_name) sub_names) } -- main_name is not bound here! - - new_assoc :: LInstDecl RdrName -> RnM [AvailInfo] - new_assoc (L _ (FamInstDecl d)) - = do { avail <- new_ti Nothing d - ; return [avail] } - new_assoc (L _ (ClsInstDecl inst_ty _ _ ats)) - = do { mb_cls_nm <- get_cls_parent inst_ty - ; mapM (new_ti mb_cls_nm . unLoc) ats } - where - get_cls_parent inst_ty - | Just (_, _, L loc cls_rdr, _) <- splitLHsInstDeclTy_maybe inst_ty - = setSrcSpan loc $ do { nm <- lookupGlobalOccRn cls_rdr; return (Just nm) } - | otherwise - = return Nothing - -lookupTcdName :: Maybe Name -> TyClDecl RdrName -> RnM (Located Name) --- Used for TyData and TySynonym only, --- both ordinary ones and family instances --- See Note [Family instance binders] -lookupTcdName mb_cls tc_decl - | not (isFamInstDecl tc_decl) -- The normal case - = ASSERT2( isNothing mb_cls, ppr tc_rdr ) -- Parser prevents this - lookupLocatedTopBndrRn tc_rdr - - | Just cls <- mb_cls -- Associated type; c.f RnBinds.rnMethodBind - = wrapLocM (lookupInstDeclBndr cls (ptext (sLit "associated type"))) tc_rdr - - | otherwise -- Family instance; tc_rdr is an *occurrence* - = lookupLocatedOccRn tc_rdr - where - tc_rdr = tcdLName tc_decl \end{code} Note [Looking up family names in family instances] @@ -586,41 +567,6 @@ Solution is simple: process the type family declarations first, extend the environment, and then process the type instances. -Note [Family instance binders] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Consider - data family F a - data instance F T = X1 | X2 - -The 'data instance' decl has an *occurrence* of F (and T), and *binds* -X1 and X2. (This is unlike a normal data type declaration which would -bind F too.) So we want an AvailTC F [X1,X2]. - -Now consider a similar pair: - class C a where - data G a - instance C S where - data G S = Y1 | Y2 - -The 'data G S' *binds* Y1 and Y2, and has an *occurrence* of G. - -But there is a small complication: in an instance decl, we don't use -qualified names on the LHS; instead we use the class to disambiguate. -Thus: - module M where - import Blib( G ) - class C a where - data G a - instance C S where - data G S = Y1 | Y2 -Even though there are two G's in scope (M.G and Blib.G), the occurence -of 'G' in the 'instance C S' decl is unambiguous, becuase C has only -one associated type called G. This is exactly what happens for methods, -and it is only consistent to do the same thing for types. That's the -role of the function lookupTcdName; the (Maybe Name) give the class of -the encloseing instance decl, if any. - - %************************************************************************ %* * \subsection{Filtering imports} |