chore: remove binding.mutation

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

@@ -137,6 +137,7 @@ export function client_component(analysis, options) {
 		public_state: new Map(),
 		private_state: new Map(),
 		getters: {},
+		setters: {},
 		in_constructor: false,
 
 		// these are set inside the `Fragment` visitor, and cannot be used until then
@@ -624,6 +625,7 @@ export function client_module(analysis, options) {
 		public_state: new Map(),
 		private_state: new Map(),
 		getters: {},
+		setters: {},
 		in_constructor: false
 	};
 

packages/svelte/src/compiler/phases/3-transform/client/types.d.ts

@@ -4,7 +4,8 @@ import type {
 	LabeledStatement,
 	Identifier,
 	PrivateIdentifier,
-	Expression
+	Expression,
+	AssignmentExpression
 } from 'estree';
 import type { Namespace, SvelteNode, ValidatedCompileOptions } from '#compiler';
 import type { TransformState } from '../types.js';
@@ -28,6 +29,13 @@ export interface ClientTransformState extends TransformState {
 	 * will be replaced with `node` (e.g. `x` -> `$.get(x)`)
 	 */
 	readonly getters: Record<string, Expression | ((id: Identifier) => Expression)>;
+	/**
+	 * Counterpart to `getters`
+	 */
+	readonly setters: Record<
+		string,
+		(assignment: AssignmentExpression, context: Context) => Expression
+	>;
 }
 
 export interface ComponentClientTransformState extends ClientTransformState {

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

@@ -265,8 +265,10 @@ export function build_setter(node, context, fallback, prefix, options) {
 
 	if (!binding) return fallback();
 
-	if (binding.mutation !== null) {
-		return binding.mutation(node, context);
+	if (Object.hasOwn(state.setters, left.name)) {
+		const setter = state.setters[left.name];
+		// @ts-expect-error
+		return setter(node, context);
 	}
 
 	if (binding.kind === 'legacy_reactive_import') {

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

@@ -1,6 +1,6 @@
-/** @import { BlockStatement, Expression, Identifier, MemberExpression, Pattern, Statement } from 'estree' */
+/** @import { AssignmentExpression, BlockStatement, Expression, Identifier, MemberExpression, Pattern, Statement } from 'estree' */
 /** @import { Binding, EachBlock } from '#compiler' */
-/** @import { ComponentContext } from '../types' */
+/** @import { ComponentContext, Context } from '../types' */
 import {
 	EACH_INDEX_REACTIVE,
 	EACH_IS_ANIMATED,
@@ -110,7 +110,8 @@ export function EachBlock(node, context) {
 
 	const child_state = {
 		...context.state,
-		getters: { ...context.state.getters }
+		getters: { ...context.state.getters },
+		setters: { ...context.state.setters }
 	};
 
 	/** The state used when generating the key function, if necessary */
@@ -121,7 +122,7 @@ export function EachBlock(node, context) {
 
 	/**
 	 * @param {Pattern} expression_for_id
-	 * @returns {Binding['mutation']}
+	 * @returns {(assignment: AssignmentExpression, context: Context) => Expression}
 	 */
 	const create_mutation = (expression_for_id) => {
 		return (assignment, context) => {
@@ -151,7 +152,7 @@ export function EachBlock(node, context) {
 				return b.sequence(sequence);
 			} else {
 				const original_left = /** @type {MemberExpression} */ (assignment.left);
-				const left = context.visit(original_left);
+				const left = /** @type {Pattern} */ (context.visit(original_left));
 				const assign = b.assignment(assignment.operator, left, value);
 				sequence.unshift(assign);
 				return b.sequence(sequence);
@@ -184,7 +185,7 @@ export function EachBlock(node, context) {
 	const declarations = [];
 
 	if (node.context.type === 'Identifier') {
-		binding.mutation = create_mutation(
+		child_state.setters[node.context.name] = create_mutation(
 			b.member(
 				each_node_meta.array_name ? b.call(each_node_meta.array_name) : collection,
 				index,
@@ -209,7 +210,7 @@ export function EachBlock(node, context) {
 
 			const getter = needs_derived ? b.call('$.get', b.id(name)) : b.call(name);
 			child_state.getters[name] = getter;
-			binding.mutation = create_mutation(
+			child_state.setters[name] = create_mutation(
 				/** @type {Pattern} */ (path.update_expression(unwrapped))
 			);
 

packages/svelte/src/compiler/phases/scope.js

@@ -118,7 +118,6 @@ export class Scope {
 			declaration_kind,
 			is_called: false,
 			prop_alias: null,
-			mutation: null,
 			reassigned: false,
 			metadata: null
 		};

packages/svelte/src/compiler/types/index.d.ts

@@ -307,8 +307,6 @@ export interface Binding {
 	legacy_dependencies: Binding[];
 	/** Legacy props: the `class` in `{ export klass as class}`. $props(): The `class` in { class: klass } = $props() */
 	prop_alias: string | null;
-	/** If this is set, all mutations should use this expression */
-	mutation: ((assignment: AssignmentExpression, context: Context<any, any>) => Expression) | null;
 	/** Additional metadata, varies per binding type */
 	metadata: {
 		/** `true` if is (inside) a rest parameter */

packages/svelte/types/index.d.ts

@@ -584,7 +584,6 @@ declare module 'svelte/animate' {
 declare module 'svelte/compiler' {
 	import type { AssignmentExpression, ClassDeclaration, Expression, FunctionDeclaration, Identifier, ImportDeclaration, ArrayExpression, MemberExpression, ObjectExpression, Pattern, Node, VariableDeclarator, ArrowFunctionExpression, VariableDeclaration, FunctionExpression, Program, ChainExpression, SimpleCallExpression } from 'estree';
 	import type { SourceMap } from 'magic-string';
-	import type { Context } from 'zimmerframe';
 	import type { Location } from 'locate-character';
 	/**
 	 * `compile` converts your `.svelte` source code into a JavaScript module that exports a component
@@ -957,8 +956,6 @@ declare module 'svelte/compiler' {
 		legacy_dependencies: Binding[];
 		/** Legacy props: the `class` in `{ export klass as class}`. $props(): The `class` in { class: klass } = $props() */
 		prop_alias: string | null;
-		/** If this is set, all mutations should use this expression */
-		mutation: ((assignment: AssignmentExpression, context: Context<any, any>) => Expression) | null;
 		/** Additional metadata, varies per binding type */
 		metadata: {
 			/** `true` if is (inside) a rest parameter */