fix: Ignore equal reference assignments. Fixes #648

__tests__/patch.js

@@ -1256,3 +1256,24 @@ test("maps can store __proto__, prototype and constructor props", () => {
 	expect(newMap.get("prototype").polluted).toBe("yes")
 	expect(obj.polluted).toBe(undefined)
 })
+
+test("#648 assigning object to itself should not change patches", () => {
+	const input = {
+		obj: {
+			value: 200
+		}
+	}
+
+	const [nextState, patches] = produceWithPatches(input, draft => {
+		draft.obj.value = 1
+		draft.obj = draft.obj
+	})
+
+	expect(patches).toEqual([
+		{
+			op: "replace",
+			path: ["obj", "value"],
+			value: 1
+		}
+	])
+})

src/core/proxy.ts

@@ -157,6 +157,9 @@ export const objectTraps: ProxyHandler<ProxyState> = {
 			prepareCopy(state)
 			markChanged(state)
 		}
+
+		if (state.copy_![prop] === value && typeof value !== "number") return true
+
 		// @ts-ignore
 		state.copy_![prop] = value
 		state.assigned_[prop] = true