Index: src/AST/Pass.impl.hpp
===================================================================
--- src/AST/Pass.impl.hpp	(revision 4c868cb2d605f52664207c4a1a18ed9f041e2057)
+++ src/AST/Pass.impl.hpp	(revision 7a8f62c3b4eb778892c95845d9cfbbf5e3c0d521)
@@ -67,11 +67,7 @@
 		}
 
-		/// mutate should NEVER create new decl since it risks invalidating weak refs
-		/// called by visit template with correct type information so static type checking should suffice
 		template< typename core_t, typename node_t >
 		static inline node_t* mutate(const node_t *node) {
-			// force copying non-decl nodes as a pure function
-			return std::is_base_of<PureVisitor, core_t>::value && !std::is_base_of<ast::Decl, node_t>::value
-			? ::ast::shallowCopy(node) : ::ast::mutate(node);
+			return std::is_base_of<PureVisitor, core_t>::value ? ::ast::shallowCopy(node) : ::ast::mutate(node);
 		}