1 files changed, 9 insertions, 2 deletions
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 77a1a7f4990..67feef16f26 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -2311,9 +2311,16 @@ ASTNodeImporter::VisitTypedefNameDecl(TypedefNameDecl *D, bool IsAlias) {
       if (!FoundDecl->isInIdentifierNamespace(IDNS))
         continue;
       if (auto *FoundTypedef = dyn_cast<TypedefNameDecl>(FoundDecl)) {
-        if (Importer.IsStructurallyEquivalent(
-                D->getUnderlyingType(), FoundTypedef->getUnderlyingType()))
+        QualType FromUT = D->getUnderlyingType();
+        QualType FoundUT = FoundTypedef->getUnderlyingType();
+        if (Importer.IsStructurallyEquivalent(FromUT, FoundUT)) {
+          // If the "From" context has a complete underlying type but we
+          // already have a complete underlying type then return with that.
+          if (!FromUT->isIncompleteType() && !FoundUT->isIncompleteType())
             return Importer.MapImported(D, FoundTypedef);
+        }
+        // FIXME Handle redecl chain.
+        break;
       }
 
       ConflictingDecls.push_back(FoundDecl);