warn when component includes one-time reactive declarations

src/compiler/compile/render_dom/index.ts

@@ -402,6 +402,15 @@ export default function dom(
 			`;
 		}
 		
+		if (component.compile_options.dev && fixed_reactive_declarations.length) {
+			fixed_reactive_declarations.forEach((v) =>
+				component.warn(v, {
+					code: "one-time-reactive-declaration",
+					message: `${component.name.name} includes a one-time reactive declaration, consider making it a part of the static top level statements instead.`,
+				})
+			);
+		}
+
 		const return_value = {
 			type: 'ArrayExpression',
 			elements: initial_context.map(member => ({