fix: improve consttag ordering in non-runes mode

.changeset/cold-lamps-accept.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: sort `{@const ...}` tags topologically in legacy mode

packages/svelte/messages/compile-errors/template.md

@@ -96,6 +96,10 @@
 
 > This type of directive is not valid on components
 
+## const_tag_cycle
+
+> Cyclical dependency detected: %cycle%
+
 ## const_tag_invalid_expression
 
 > {@const ...} must consist of a single variable declaration

packages/svelte/src/compiler/errors.js

@@ -752,6 +752,16 @@ export function component_invalid_directive(node) {
 	e(node, "component_invalid_directive", "This type of directive is not valid on components");
 }
 
+/**
+ * Cyclical dependency detected: %cycle%
+ * @param {null | number | NodeLike} node
+ * @param {string} cycle
+ * @returns {never}
+ */
+export function const_tag_cycle(node, cycle) {
+	e(node, "const_tag_cycle", `Cyclical dependency detected: ${cycle}`);
+}
+
 /**
  * {@const ...} must consist of a single variable declaration
  * @param {null | number | NodeLike} node

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

@@ -48,55 +48,6 @@ export function client_component(source, analysis, options) {
 		scopes: analysis.template.scopes,
 		hoisted: [b.import_all('$', 'svelte/internal/client')],
 		node: /** @type {any} */ (null), // populated by the root node
-		// these should be set by create_block - if they're called outside, it's a bug
-		get before_init() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('before_init.push should not be called outside create_block');
-			};
-			return a;
-		},
-		get init() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('init.push should not be called outside create_block');
-			};
-			return a;
-		},
-		get update() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('update.push should not be called outside create_block');
-			};
-			return a;
-		},
-		get after_update() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('after_update.push should not be called outside create_block');
-			};
-			return a;
-		},
-		get template() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('template.push should not be called outside create_block');
-			};
-			return a;
-		},
-		get locations() {
-			/** @type {any[]} */
-			const a = [];
-			a.push = () => {
-				throw new Error('locations.push should not be called outside create_block');
-			};
-			return a;
-		},
 		legacy_reactive_statements: new Map(),
 		metadata: {
 			context: {
@@ -110,7 +61,15 @@ export function client_component(source, analysis, options) {
 		preserve_whitespace: options.preserveWhitespace,
 		public_state: new Map(),
 		private_state: new Map(),
-		in_constructor: false
+		in_constructor: false,
+
+		// these are set inside the `Fragment` visitor, and cannot be used until then
+		before_init: /** @type {any} */ (null),
+		init: /** @type {any} */ (null),
+		update: /** @type {any} */ (null),
+		after_update: /** @type {any} */ (null),
+		template: /** @type {any} */ (null),
+		locations: /** @type {any} */ (null)
 	};
 
 	const module = /** @type {import('estree').Program} */ (

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

@@ -49,9 +49,9 @@ export interface ComponentClientTransformState extends ClientTransformState {
 		namespace: Namespace;
 		bound_contenteditable: boolean;
 		/**
-		 * Stuff that is set within the children of one `create_block` that is relevant
-		 * to said `create_block`. Shouldn't be destructured or otherwise spread unless
-		 * inside `create_block` to keep the object reference intact (it's also nested
+		 * Stuff that is set within the children of one `Fragment` visitor that is relevant
+		 * to said fragment. Shouldn't be destructured or otherwise spread unless inside the
+		 * `Fragment` visitor to keep the object reference intact (it's also nested
 		 * within `metadata` for this reason).
 		 */
 		context: {