fix: remove overzealous `reactive_declaration_non_reactive_property` warning (#14663)

fixes #14532

This removes the `reactive_declaration_non_reactive_property` warning altogether. The first version caused many false positives at compile time. The refined runtime version (introduced in #14192) was hoped to fix this, but it turns out we now get loads of false positives at runtime.

.changeset/purple-adults-arrive.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: remove overzealous `reactive_declaration_non_reactive_property` warning

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

@@ -204,46 +204,6 @@ Consider the following code:
 
 To fix it, either create callback props to communicate changes, or mark `person` as [`$bindable`]($bindable).
 
-### reactive_declaration_non_reactive_property
-
-```
-A `$:` statement (%location%) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode
-```
-
-In legacy mode, a `$:` [reactive statement](https://svelte.dev/docs/svelte/legacy-reactive-assignments) re-runs when the state it _references_ changes. This is determined at compile time, by analysing the code.
-
-In runes mode, effects and deriveds re-run when there are changes to the values that are read during the function's _execution_.
-
-Often, the result is the same — for example these can be considered equivalent:
-
-```js
-let a = 1, b = 2, sum = 3;
-// ---cut---
-$: sum = a + b;
-```
-
-```js
-let a = 1, b = 2;
-// ---cut---
-const sum = $derived(a + b);
-```
-
-In some cases — such as the one that triggered the above warning — they are _not_ the same:
-
-```js
-let a = 1, b = 2, sum = 3;
-// ---cut---
-const add = () => a + b;
-
-// the compiler can't 'see' that `sum` depends on `a` and `b`, but
-// they _would_ be read while executing the `$derived` version
-$: sum = add();
-```
-
-Similarly, reactive properties of [deep state](https://svelte.dev/docs/svelte/$state#Deep-state) are not visible to the compiler. As such, changes to these properties will cause effects and deriveds to re-run but will _not_ cause `$:` statements to re-run.
-
-When you [migrate this component](https://svelte.dev/docs/svelte/v5-migration-guide) to runes mode, the behaviour will change accordingly.
-
 ### state_proxy_equality_mismatch
 
 ```

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

@@ -170,44 +170,6 @@ Consider the following code:
 
 To fix it, either create callback props to communicate changes, or mark `person` as [`$bindable`]($bindable).
 
-## reactive_declaration_non_reactive_property
-
-> A `$:` statement (%location%) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode
-
-In legacy mode, a `$:` [reactive statement](https://svelte.dev/docs/svelte/legacy-reactive-assignments) re-runs when the state it _references_ changes. This is determined at compile time, by analysing the code.
-
-In runes mode, effects and deriveds re-run when there are changes to the values that are read during the function's _execution_.
-
-Often, the result is the same — for example these can be considered equivalent:
-
-```js
-let a = 1, b = 2, sum = 3;
-// ---cut---
-$: sum = a + b;
-```
-
-```js
-let a = 1, b = 2;
-// ---cut---
-const sum = $derived(a + b);
-```
-
-In some cases — such as the one that triggered the above warning — they are _not_ the same:
-
-```js
-let a = 1, b = 2, sum = 3;
-// ---cut---
-const add = () => a + b;
-
-// the compiler can't 'see' that `sum` depends on `a` and `b`, but
-// they _would_ be read while executing the `$derived` version
-$: sum = add();
-```
-
-Similarly, reactive properties of [deep state](https://svelte.dev/docs/svelte/$state#Deep-state) are not visible to the compiler. As such, changes to these properties will cause effects and deriveds to re-run but will _not_ cause `$:` statements to re-run.
-
-When you [migrate this component](https://svelte.dev/docs/svelte/v5-migration-guide) to runes mode, the behaviour will change accordingly.
-
 ## state_proxy_equality_mismatch
 
 > Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results

packages/svelte/src/compiler/phases/3-transform/client/visitors/LabeledStatement.js

@@ -50,11 +50,6 @@ export function LabeledStatement(node, context) {
 		sequence.push(serialized);
 	}
 
-	const location =
-		dev && !is_ignored(node, 'reactive_declaration_non_reactive_property')
-			? locator(/** @type {number} */ (node.start))
-			: undefined;
-
 	// these statements will be topologically ordered later
 	context.state.legacy_reactive_statements.set(
 		node,
@@ -62,9 +57,7 @@ export function LabeledStatement(node, context) {
 			b.call(
 				'$.legacy_pre_effect',
 				sequence.length > 0 ? b.thunk(b.sequence(sequence)) : b.thunk(b.block([])),
-				b.thunk(b.block(body)),
+				b.thunk(b.block(body))
-				location && b.literal(location.line),
-				location && b.literal(location.column)
 			)
 		)
 	);

packages/svelte/src/constants.js

@@ -44,8 +44,7 @@ export const IGNORABLE_RUNTIME_WARNINGS = /** @type {const} */ ([
 	'hydration_attribute_changed',
 	'hydration_html_changed',
 	'ownership_invalid_binding',
-	'ownership_invalid_mutation',
+	'ownership_invalid_mutation'
-	'reactive_declaration_non_reactive_property'
 ]);
 
 /**

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

@@ -265,21 +265,14 @@ export function effect(fn) {
  * Internal representation of `$: ..`
  * @param {() => any} deps
  * @param {() => void | (() => void)} fn
- * @param {number} [line]
- * @param {number} [column]
  */
-export function legacy_pre_effect(deps, fn, line, column) {
+export function legacy_pre_effect(deps, fn) {
 	var context = /** @type {ComponentContextLegacy} */ (component_context);
 
 	/** @type {{ effect: null | Effect, ran: boolean }} */
 	var token = { effect: null, ran: false };
 	context.l.r1.push(token);
 
-	if (DEV && line !== undefined) {
-		var location = get_location(line, column);
-		var explicit_deps = capture_signals(deps);
-	}
-
 	token.effect = render_effect(() => {
 		deps();
 
@@ -289,18 +282,7 @@ export function legacy_pre_effect(deps, fn, line, column) {
 
 		token.ran = true;
 		set(context.l.r2, true);
-
-		if (DEV && location) {
-			var implicit_deps = capture_signals(() => untrack(fn));
-
-			for (var signal of implicit_deps) {
-				if (!explicit_deps.has(signal)) {
-					w.reactive_declaration_non_reactive_property(/** @type {string} */ (location));
-				}
-			}
-		} else {
 		untrack(fn);
-		}
 	});
 }
 

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

@@ -155,18 +155,6 @@ export function ownership_invalid_mutation(component, owner) {
 	}
 }
 
-/**
- * A `$:` statement (%location%) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode
- * @param {string} location
- */
-export function reactive_declaration_non_reactive_property(location) {
-	if (DEV) {
-		console.warn(`%c[svelte] reactive_declaration_non_reactive_property\n%cA \`$:\` statement (${location}) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode\nhttps://svelte.dev/e/reactive_declaration_non_reactive_property`, bold, normal);
-	} else {
-		console.warn(`https://svelte.dev/e/reactive_declaration_non_reactive_property`);
-	}
-}
-
 /**
  * Reactive `$state(...)` proxies and the values they proxy have different identities. Because of this, comparisons with `%operator%` will produce unexpected results
  * @param {string} operator

packages/svelte/tests/runtime-legacy/samples/reactive-statement-non-reactive-import-statement/_config.js

@@ -1,26 +0,0 @@
-import { flushSync } from 'svelte';
-import { test } from '../../test';
-
-export default test({
-	compileOptions: {
-		dev: true
-	},
-
-	html: '<p>42</p><p>42</p><button>update</button><button>reset</button>',
-
-	test({ assert, target }) {
-		const [update, reset] = target.querySelectorAll('button');
-		flushSync(() => update.click());
-
-		assert.htmlEqual(
-			target.innerHTML,
-			'<p>42</p><p>42</p><button>update</button><button>reset</button>'
-		);
-
-		flushSync(() => reset.click());
-	},
-
-	warnings: [
-		'A `$:` statement (main.svelte:4:1) read reactive state that was not visible to the compiler. Updates to this state will not cause the statement to re-run. The behaviour of this code will change if you migrate it to runes mode'
-	]
-});

packages/svelte/tests/runtime-legacy/samples/reactive-statement-non-reactive-import-statement/data.svelte.js

@@ -1,11 +0,0 @@
-export const obj = $state({
-	prop: 42
-});
-
-export function update() {
-	obj.prop += 1;
-}
-
-export function reset() {
-	obj.prop = 42;
-}

packages/svelte/tests/runtime-legacy/samples/reactive-statement-non-reactive-import-statement/main.svelte

@@ -1,13 +0,0 @@
-<script>
-	import { obj, update, reset } from './data.svelte.js';
-
-	$: a = obj.prop;
-
-	// svelte-ignore reactive_declaration_non_reactive_property
-	$: b = obj.prop;
-</script>
-
-<p>{a}</p>
-<p>{b}</p>
-<button on:click={update}>update</button>
-<button on:click={reset}>reset</button>