Update for TS7

I am testing Typescript 7's JS support, which I've largely rewritten
during the switch to Go. That means Javascript code will need to change
much more than Typescript code. Fortunately, most of the changes are for
the better: Javascript semantics are now nearly identical to Typescript
semantics. It's much stricter and no longer has some persistent bugs
that arose from shady JS handling I wrote years ago.

This PR changes Svelte so that it compiles both with TS5.* and TS7,
which means that occasionally there are duplicative or non-obvious
changes. I'll annotate the interesting changes to explain why I made them.

Because TS7 is quite a way off, I don't know whether you'll want to take
this PR. Most of the changes are for the better, because they're due to
stricter TS-aligned checking. But some are neutral and there is the
previously mentioned duplication in a few places.

Author: sandersn

packages/svelte/scripts/generate-types.js

@@ -26,7 +26,7 @@ await createBundle({
 		// so that types/properties with `@internal` (and its dependencies) are removed from the output
 		stripInternal: true,
 		paths: Object.fromEntries(
-			Object.entries(pkg.imports).map(([key, value]) => {
+			Object.entries(pkg.imports).map(/** @param {[string,any]} import */([key, value]) => {
 				return [key, [value.types ?? value.default ?? value]];
 			})
 		)

packages/svelte/src/compiler/index.js

@@ -82,6 +82,7 @@ export function compileModule(source, options) {
  * @returns {AST.Root}
  */
 
+// TODO 6.0 remove unused `filename`
 /**
  * The parse function parses a component, returning only its abstract syntax tree.
  *
@@ -94,7 +95,6 @@ export function compileModule(source, options) {
  * @returns {Record<string, any>}
  */
 
-// TODO 6.0 remove unused `filename`
 /**
  * The parse function parses a component, returning only its abstract syntax tree.
  *
@@ -123,6 +123,8 @@ export function parse(source, { modern, loose } = {}) {
  * @param {boolean | undefined} modern
  */
 function to_public_ast(source, ast, modern) {
+	/** @type {AST.Root} */
+	const rrrrr = parse('hi', { modern: true }); // ensure that the modern AST is available
 	if (modern) {
 		const clean = (/** @type {any} */ node) => {
 			delete node.metadata;

packages/svelte/src/compiler/legacy.js

@@ -55,7 +55,7 @@ export function convert(source, ast) {
 
 				// Insert svelte:options back into the root nodes
 				if (/** @type {any} */ (options)?.__raw__) {
-					let idx = node.fragment.nodes.findIndex((node) => options.end <= node.start);
+					let idx = node.fragment.nodes.findIndex((node) => /** @type {any} */ (options).end <= node.start);
 					if (idx === -1) {
 						idx = node.fragment.nodes.length;
 					}

packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js

@@ -9,8 +9,8 @@ import {
 import { regex_ends_with_whitespace, regex_starts_with_whitespace } from '../../patterns.js';
 import { get_attribute_chunks, is_text_attribute } from '../../../utils/ast.js';
 
-/** @typedef {NODE_PROBABLY_EXISTS | NODE_DEFINITELY_EXISTS} NodeExistsValue */
-/** @typedef {FORWARD | BACKWARD} Direction */
+/** @typedef {typeof NODE_PROBABLY_EXISTS | typeof NODE_DEFINITELY_EXISTS} NodeExistsValue */
+/** @typedef {typeof FORWARD | typeof BACKWARD} Direction */
 
 const NODE_PROBABLY_EXISTS = 0;
 const NODE_DEFINITELY_EXISTS = 1;

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -295,7 +295,7 @@ export function analyze_module(source, options) {
 			// TODO the following are not needed for modules, but we have to pass them in order to avoid type error,
 			// and reducing the type would result in a lot of tedious type casts elsewhere - find a good solution one day
 			ast_type: /** @type {any} */ (null),
-			component_slots: new Set(),
+			component_slots: /** @type {Set<string>} */ (new Set()),
 			expression: null,
 			function_depth: 0,
 			has_props_rune: false,

packages/svelte/src/compiler/phases/2-analyze/utils/check_graph_for_cycles.js

@@ -14,6 +14,7 @@ export default function check_graph_for_cycles(edges) {
 	}, new Map());
 
 	const visited = new Set();
+	/** @type {Set<T>} */
 	const on_stack = new Set();
 	/** @type {Array<Array<T>>} */
 	const cycles = [];

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js

@@ -599,7 +599,7 @@ function has_disabled_attribute(attribute_map) {
 /**
  * @param {string} tag_name
  * @param {Map<string, AST.Attribute>} attribute_map
- * @returns {ElementInteractivity[keyof ElementInteractivity]}
+ * @returns {typeof ElementInteractivity[keyof typeof ElementInteractivity]}
  */
 function element_interactivity(tag_name, attribute_map) {
 	if (

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js

@@ -145,6 +145,7 @@ export function visit_component(node, context) {
 		if (slot_name !== 'default') comments = [];
 	}
 
+	/** @type {Set<string>} */
 	const component_slots = new Set();
 
 	for (const slot_name in nodes) {

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

@@ -22,7 +22,7 @@ const NUMBER = Symbol('number');
 const STRING = Symbol('string');
 const FUNCTION = Symbol('string');
 
-/** @type {Record<string, [type: NUMBER | STRING | UNKNOWN, fn?: Function]>} */
+/** @type {Record<string, [type: typeof NUMBER | typeof  STRING | typeof  UNKNOWN, fn?: Function]>} */
 const globals = {
 	BigInt: [NUMBER],
 	'Math.min': [NUMBER, Math.min],

packages/svelte/src/compiler/state.js

@@ -87,7 +87,7 @@ export function pop_ignore() {
 
 /**
  * @param {AST.SvelteNode | NodeLike} node
- * @param {import('../constants.js').IGNORABLE_RUNTIME_WARNINGS[number]} code
+ * @param {typeof import('../constants.js').IGNORABLE_RUNTIME_WARNINGS[number]} code
  * @returns
  */
 export function is_ignored(node, code) {