[modules] When considering merging a newly-declared typedef into an imported
one, perform the import if the types match even if the imported declaration is
hidden. Otherwise, NamedDecl::declarationReplaces will drop one of the name
lookup entries, making the typedef effectively inaccessible from one of the
modules that declared it.
llvm-svn: 215306
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 5f65593..85c88a3 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -1725,6 +1725,43 @@
filter.done();
}
+/// Typedef declarations don't have linkage, but they still denote the same
+/// entity if their types are the same.
+/// FIXME: This is notionally doing the same thing as ASTReaderDecl's
+/// isSameEntity.
+static void filterNonConflictingPreviousTypedefDecls(ASTContext &Context,
+ TypedefNameDecl *Decl,
+ LookupResult &Previous) {
+ // This is only interesting when modules are enabled.
+ if (!Context.getLangOpts().Modules)
+ return;
+
+ // Empty sets are uninteresting.
+ if (Previous.empty())
+ return;
+
+ LookupResult::Filter Filter = Previous.makeFilter();
+ while (Filter.hasNext()) {
+ NamedDecl *Old = Filter.next();
+
+ // Non-hidden declarations are never ignored.
+ if (!Old->isHidden())
+ continue;
+
+ // Declarations of the same entity are not ignored, even if they have
+ // different linkages.
+ if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old))
+ if (Context.hasSameType(OldTD->getUnderlyingType(),
+ Decl->getUnderlyingType()))
+ continue;
+
+ if (!Old->isExternallyVisible())
+ Filter.erase();
+ }
+
+ Filter.done();
+}
+
bool Sema::isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New) {
QualType OldType;
if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
@@ -4835,7 +4872,7 @@
// in an outer scope, it isn't the same thing.
FilterLookupForScope(Previous, DC, S, /*ConsiderLinkage*/false,
/*AllowInlineNamespace*/false);
- filterNonConflictingPreviousDecls(Context, NewTD, Previous);
+ filterNonConflictingPreviousTypedefDecls(Context, NewTD, Previous);
if (!Previous.empty()) {
Redeclaration = true;
MergeTypedefNameDecl(NewTD, Previous);