diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
index 6fe85a1298fcb..783a5f1788039 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp
@@ -482,6 +482,15 @@ void ClangASTSource::FindExternalLexicalDecls(
       if (!copied_decl)
         continue;
 
+      // FIXME: We should add the copied decl to the 'decls' list. This would
+      // add the copied Decl into the DeclContext and make sure that we
+      // correctly propagate that we added some Decls back to Clang.
+      // By leaving 'decls' empty we incorrectly return false from
+      // DeclContext::LoadLexicalDeclsFromExternalStorage which might cause
+      // lookup issues later on.
+      // We can't just add them for now as the ASTImporter already added the
+      // decl into the DeclContext and this would add it twice.
+
       if (FieldDecl *copied_field = dyn_cast<FieldDecl>(copied_decl)) {
         QualType copied_field_type = copied_field->getType();