Commit 9366e019 authored by's avatar

Fix Trac #8485.

The problem was that the renamer treated role annotations by looking
up the annotated type in the module being compiled. If this check
succeeded, it was assumed that the annotated type was being compiled
at the same time. But this assumption is false! In GHCi (and Template
Haskell), sometimes compilation within one module can be staged. So,
now there is a more intricate check for orphan role annotations. This
also has the benefit of producing better error messages.
parent 7cb10ba4
......@@ -22,7 +22,7 @@ module RnEnv (
lookupSubBndrGREs, lookupConstructorFields,
lookupSyntaxName, lookupSyntaxNames, lookupIfThenElse,
lookupGreRn, lookupGreRn_maybe,
lookupGlobalOccInThisModule, lookupGreLocalRn_maybe,
getLookupOccRn, addUsedRdrNames,
newLocalBndrRn, newLocalBndrsRn,
......@@ -704,19 +704,6 @@ lookupGreLocalRn_maybe rdr_name
lookup_fn env = filter isLocalGRE (lookupGRE_RdrName rdr_name env)
lookupGlobalOccInThisModule :: RdrName -> RnM Name
-- If not found, add error message
lookupGlobalOccInThisModule rdr_name
| Just n <- isExact_maybe rdr_name
= do { n' <- lookupExactOcc n; return n' }
| otherwise
= do { mb_gre <- lookupGreLocalRn_maybe rdr_name
; case mb_gre of
Just gre -> return $ gre_name gre
Nothing -> do { traceRn (text "lookupGlobalInThisModule" <+> ppr rdr_name)
; unboundName WL_LocalTop rdr_name } }
lookupGreRn_help :: RdrName -- Only used in error message
-> (GlobalRdrEnv -> [GlobalRdrElt]) -- Lookup function
-> RnM (Maybe GlobalRdrElt)
......@@ -892,12 +892,21 @@ rnTyClDecls extra_deps tycl_ds
raw_groups = map flattenSCC sccs
-- See Note [Role annotations in the renamer]
groups = [ TyClGroup { group_tyclds = gp
, group_roles = roles }
| gp <- raw_groups
, let roles = mapMaybe ( lookupNameEnv role_annot_env
. tcdName
. unLoc ) gp ]
(groups, orphan_roles)
= foldr (\group (groups_acc, orphans_acc) ->
let names = map (tcdName . unLoc) group
roles = mapMaybe (lookupNameEnv orphans_acc) names
orphans' = delListFromNameEnv orphans_acc names
-- there doesn't seem to be an interface to
-- do the above more efficiently
in ( TyClGroup { group_tyclds = group
, group_roles = roles } : groups_acc
, orphans' )
([], role_annot_env)
; mapM_ orphanRoleAnnotErr (nameEnvElts orphan_roles)
; traceRn (text "rnTycl" <+> (ppr ds_w_fvs $$ ppr sccs))
; return (groups, all_fvs) }
......@@ -1031,7 +1040,7 @@ rnRoleAnnots role_annots
rn_role_annot1 (RoleAnnotDecl tycon roles)
= do { -- the name is an *occurrence*
tycon' <- wrapLocM lookupGlobalOccInThisModule tycon
tycon' <- wrapLocM lookupGlobalOccRn tycon
; return $ RoleAnnotDecl tycon' roles }
dupRoleAnnotErr :: [LRoleAnnotDecl RdrName] -> RnM ()
......@@ -1050,6 +1059,15 @@ dupRoleAnnotErr list
cmp_annot (L loc1 _) (L loc2 _) = loc1 `compare` loc2
orphanRoleAnnotErr :: LRoleAnnotDecl Name -> RnM ()
orphanRoleAnnotErr (L loc decl)
= addErrAt loc $
hang (text "Role annotation for a type previously declared:")
2 (ppr decl) $$
parens (text "The role annotation must be given where" <+>
quotes (ppr $ roleAnnotDeclName decl) <+>
text "is declared.")
rnDataDefn :: HsDocContext -> HsDataDefn RdrName -> RnM (HsDataDefn Name, FreeVars)
rnDataDefn doc (HsDataDefn { dd_ND = new_or_data, dd_cType = cType
, dd_ctxt = context, dd_cons = condecls
......@@ -1186,14 +1204,25 @@ type, if any. Then, this map can be used to add the role annotations to the
groups after dependency analysis.
This process checks for duplicate role annotations, where we must be careful
to filter out the unbound annotations to avoid reporting spurious duplicates.
We hold off doing other checks until validity checking in the type checker.
Also, note that the tycon in a role annotation is renamed with
lookupGlobalInThisModule. We want only annotations for local declarations.
Because all of these are in scope by this point, this renaming technique
also effectively identifies any orphan role annotations. Annotations on
declarations that don't support them is checked for in the type-checker.
to do the check *before* renaming to avoid calling all unbound names duplicates
of one another.
The renaming process, as usual, might identify and report errors for unbound
names. We exclude the annotations for unbound names in the annotation
environment to avoid spurious errors for orphaned annotations.
We then (in rnTyClDecls) do a check for orphan role annotations (role
annotations without an accompanying type decl). The check works by folding
over raw_groups (of type [[TyClDecl Name]]), selecting out the relevant
role declarations for each group, as well as diminishing the annotation
environment. After the fold is complete, anything left over in the name
environment must be an orphan, and errors are generated.
An earlier version of this algorithm short-cut the orphan check by renaming
only with names declared in this module. But, this check is insufficient in
the case of staged module compilation (Template Haskell, GHCi).
See #8485. With the new lookup process (which includes types declared in other
modules), we get better error messages, too.
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