Support freezing states that contain typed arrays

[targos]

🚀 Feature Proposal

We would like that recursive freeze works when the state contains typed arrays.

We don't expect typed arrays to be draftable, but to be able to use them in the state managed by Immer (like a native Date for example).

Motivation

Before v11.0.0, the freeze function skipped non-draftable objects:

immer/src/utils/common.ts

Lines 210 to 211 in e1996ce

	export function freeze<T>(obj: any, deep: boolean = false): T {
	if (isFrozen(obj) || isDraft(obj) || !isDraftable(obj)) return obj

Now it's no the case anymore:

immer/src/utils/common.ts

Lines 245 to 246 in d6c1202

	export function freeze<T>(obj: any, deep: boolean = false): T {
	if (isFrozen(obj) || isDraft(obj)) return obj

The effect of the new behaviour with typed arrays is that now it throws an error because we are not allowed to call Object.freeze on them:

> require('immer').produce({test: new Uint8Array(10)}, (x) => x)
Uncaught TypeError: Cannot freeze array buffer views with elements
    at Object.freeze (<anonymous>)
    at freeze (/project/node_modules/immer/dist/cjs/immer.cjs.development.js:236:5)
    at /project/node_modules/immer/dist/cjs/immer.cjs.development.js:241:9

Can this be solved in user-land code?

I don't think so (except by disabling auto-freeze).

Example

import { produce } from 'immer';

const state = {
  data: new Uint8Array(10)
};

const newState = produce(state, (draft) => {
  draft.data = new Uint8Array(15);
});

[markerikson]

I think I removed that because the isDraftable check then does a half-dozen more type instance checks (plain object, array, etc), and that was proving to be a hotspot.

I can go re-run my benchmarks and see how much of a difference it makes with the current implementation.

[Methuselah96]

We are having a similar issue with objects that contain classes.

For example, this used to work with immer 10, but throws an error in immer 11:

import { produce } from 'immer';

class MutableClass {
  value = 5;
}

const myObject = { someValue: 5, mutableClass: new MutableClass() };
const modifiedObject = produce(myObject, draft => {
  draft.someValue = 6;
});

modifiedObject.mutableClass.value = 6;

[Methuselah96]

I created #1192 as a separate issue to track the regression from v10 to v11, since this one sounds like it's just a feature proposal

[markerikson]

No, both of these really are the same issue, just manifesting differently (typed arrays throw as soon as you freeze them, classes throw if you mutate after freezing). I removed the || !isDraftable(obj) from freeze() in #1183, and can confirm that re-adding it fixes both of these cases.

Just put up #1193 to fix this.

Re-ran my benchmarks a few times. Results are a bit noisy, but in the ballpark enough that I don't see an immediately obviously meaningful difference in perf, so should be fine to add this back in.

[targos]

Thanks!

[markerikson]

Will need to wait on @mweststrate to publish the bugfix as 11.0.1, but worst case you can monkey-patch that locally.

[github-actions]

🎉 This issue has been resolved in version 11.0.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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