remove state_unsafe_local_read error

Author: Rich-Harris

documentation/docs/98-reference/.generated/client-errors.md

@@ -122,12 +122,6 @@ Property descriptors defined on `$state` objects must contain `value` and always
 Cannot set prototype of `$state` object
 ```
 
-### state_unsafe_local_read
-
-```
-Reading state that was created inside the same derived is forbidden. Consider using `untrack` to read locally created state
-```
-
 ### state_unsafe_mutation
 
 ```

packages/svelte/messages/client-errors/errors.md

@@ -80,10 +80,6 @@ See the [migration guide](/docs/svelte/v5-migration-guide#Components-are-no-long
 
 > Cannot set prototype of `$state` object
 
-## state_unsafe_local_read
-
-> Reading state that was created inside the same derived is forbidden. Consider using `untrack` to read locally created state
-
 ## state_unsafe_mutation
 
 > Updating state inside a derived or a template expression is forbidden. If the value should not be reactive, declare it without `$state`

packages/svelte/src/internal/client/errors.js

@@ -307,21 +307,6 @@ export function state_prototype_fixed() {
 	}
 }
 
-/**
- * Reading state that was created inside the same derived is forbidden. Consider using `untrack` to read locally created state
- * @returns {never}
- */
-export function state_unsafe_local_read() {
-	if (DEV) {
-		const error = new Error(`state_unsafe_local_read\nReading state that was created inside the same derived is forbidden. Consider using \`untrack\` to read locally created state\nhttps://svelte.dev/e/state_unsafe_local_read`);
-
-		error.name = 'Svelte error';
-		throw error;
-	} else {
-		throw new Error(`https://svelte.dev/e/state_unsafe_local_read`);
-	}
-}
-
 /**
  * Updating state inside a derived or a template expression is forbidden. If the value should not be reactive, declare it without `$state`
  * @returns {never}

packages/svelte/src/internal/client/index.js

@@ -113,7 +113,14 @@ export {
 	user_effect,
 	user_pre_effect
 } from './reactivity/effects.js';
-export { mutable_source, mutate, set, state, update, update_pre } from './reactivity/sources.js';
+export {
+	mutable_source,
+	mutate,
+	set,
+	source as state,
+	update,
+	update_pre
+} from './reactivity/sources.js';
 export {
 	prop,
 	rest_props,

packages/svelte/src/internal/client/reactivity/sources.js

@@ -11,8 +11,6 @@ import {
 	untrack,
 	increment_write_version,
 	update_effect,
-	derived_sources,
-	set_derived_sources,
 	check_dirtiness,
 	untracking,
 	is_destroying_effect
@@ -51,6 +49,7 @@ export function set_inspect_effects(v) {
  * @param {Error | null} [stack]
  * @returns {Source<V>}
  */
+// TODO rename this to `state` throughout the codebase
 export function source(v, stack) {
 	/** @type {Value} */
 	var signal = {
@@ -71,25 +70,6 @@ export function source(v, stack) {
 	return signal;
 }
 
-/**
- * @template V
- * @param {V} v
- */
-export function state(v) {
-	var s = source(v);
-
-	// TODO maybe we make this dev-only?
-	if (active_reaction !== null && !untracking && (active_reaction.f & DERIVED) !== 0) {
-		if (derived_sources === null) {
-			set_derived_sources([s]);
-		} else {
-			derived_sources.push(s);
-		}
-	}
-
-	return s;
-}
-
 /**
  * @template V
  * @param {V} initial_value

packages/svelte/src/internal/client/runtime.js

@@ -86,20 +86,6 @@ export function set_active_effect(effect) {
 	active_effect = effect;
 }
 
-/**
- * When sources are created within a derived, we record them so that we can safely allow
- * local mutations to these sources without the side-effect error being invoked unnecessarily.
- * @type {null | Source[]}
- */
-export let derived_sources = null;
-
-/**
- * @param {Source[] | null} sources
- */
-export function set_derived_sources(sources) {
-	derived_sources = sources;
-}
-
 /**
  * The dependencies of the reaction that is currently being executed. In many cases,
  * the dependencies are unchanged between runs, and so this will be `null` unless
@@ -393,7 +379,6 @@ export function update_reaction(reaction) {
 	var previous_untracked_writes = untracked_writes;
 	var previous_reaction = active_reaction;
 	var previous_skip_reaction = skip_reaction;
-	var prev_derived_sources = derived_sources;
 	var previous_component_context = component_context;
 	var previous_untracking = untracking;
 	var flags = reaction.f;
@@ -405,7 +390,6 @@ export function update_reaction(reaction) {
 		(flags & UNOWNED) !== 0 && (untracking || !is_updating_effect || active_reaction === null);
 	active_reaction = (flags & (BRANCH_EFFECT | ROOT_EFFECT)) === 0 ? reaction : null;
 
-	derived_sources = null;
 	set_component_context(reaction.ctx);
 	untracking = false;
 	read_version++;
@@ -479,7 +463,6 @@ export function update_reaction(reaction) {
 		untracked_writes = previous_untracked_writes;
 		active_reaction = previous_reaction;
 		skip_reaction = previous_skip_reaction;
-		derived_sources = prev_derived_sources;
 		set_component_context(previous_component_context);
 		untracking = previous_untracking;
 	}
@@ -868,9 +851,6 @@ export function get(signal) {
 
 	// Register the dependency on the current reaction signal.
 	if (active_reaction !== null && !untracking) {
-		if (derived_sources !== null && derived_sources.includes(signal)) {
-			e.state_unsafe_local_read();
-		}
 		var deps = active_reaction.deps;
 		if (signal.rv < read_version) {
 			signal.rv = read_version;

packages/svelte/tests/signals/test.ts

@@ -8,7 +8,12 @@ import {
 	render_effect,
 	user_effect
 } from '../../src/internal/client/reactivity/effects';
-import { state, set, update, update_pre } from '../../src/internal/client/reactivity/sources';
+import {
+	source as state,
+	set,
+	update,
+	update_pre
+} from '../../src/internal/client/reactivity/sources';
 import type { Derived, Effect, Value } from '../../src/internal/client/types';
 import { proxy } from '../../src/internal/client/proxy';
 import { derived } from '../../src/internal/client/reactivity/deriveds';
@@ -958,17 +963,6 @@ describe('signals', () => {
 		};
 	});
 
-	test('deriveds cannot depend on state they own', () => {
-		return () => {
-			const d = derived(() => {
-				const s = state(0);
-				return $.get(s);
-			});
-
-			assert.throws(() => $.get(d), 'state_unsafe_local_read');
-		};
-	});
-
 	test('proxy version state does not trigger self-dependency guard', () => {
 		return () => {
 			const s = proxy({ a: { b: 1 } });