strip typescript assertions before analysis

Author: gtm-nayan

packages/svelte/src/compiler/index.js

@@ -7,6 +7,7 @@ import { walk } from 'zimmerframe';
 import { validate_component_options, validate_module_options } from './validate-options.js';
 import { convert } from './legacy.js';
 import { CompileError } from './errors.js';
+import { strip_ts_assertions } from './phases/1-parse/strip_ts_assertions.js';
 export { default as preprocess } from './preprocess/index.js';
 
 /**
@@ -20,14 +21,24 @@ export { default as preprocess } from './preprocess/index.js';
 export function compile(source, options) {
 	try {
 		const validated = validate_component_options(options, '');
-		const parsed = _parse(source);
+		let parsed = _parse(source);
 
 		const combined_options = /** @type {import('#compiler').ValidatedCompileOptions} */ ({
 			...validated,
 			...parsed.options
 		});
 
+		if (parsed.metadata.ts) {
+			parsed = {
+				...parsed,
+				fragment: parsed.fragment && strip_ts_assertions(parsed.fragment),
+				instance: parsed.instance && strip_ts_assertions(parsed.instance),
+				module: parsed.module && strip_ts_assertions(parsed.module)
+			};
+		}
+
 		const analysis = analyze_component(parsed, combined_options);
+
 		const result = transform_component(analysis, source, combined_options);
 		return result;
 	} catch (e) {

packages/svelte/src/compiler/phases/1-parse/index.js

@@ -67,7 +67,10 @@ export class Parser {
 			end: null,
 			type: 'Root',
 			fragment: create_fragment(),
-			options: null
+			options: null,
+			metadata: {
+				ts: this.ts
+			}
 		};
 
 		this.stack.push(this.root);

packages/svelte/src/compiler/phases/1-parse/strip_ts_assertions.js

@@ -0,0 +1,24 @@
+import { walk } from 'zimmerframe';
+
+/**
+ * @type {import('zimmerframe').Visitor<any, null, any>}
+ */
+function unwrap_expression_visitor(node, { visit }) {
+	return visit(node.expression);
+}
+
+/** @type {import('zimmerframe').Visitors<any, null>} */
+const visitors = {
+	TSAsExpression: unwrap_expression_visitor,
+	TSNonNullExpression: unwrap_expression_visitor,
+	TSSatisfiesExpression: unwrap_expression_visitor
+};
+
+/**
+ * @template T
+ * @param {T} ast
+ * @returns {T}
+ */
+export function strip_ts_assertions(ast) {
+	return walk(ast, null, visitors);
+}

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

@@ -56,6 +56,10 @@ export interface Root extends BaseNode {
 	instance: Script | null;
 	/** The parsed `<script context="module">` element, if exists */
 	module: Script | null;
+	metadata: {
+		/** Whether the component was parsed with typescript */
+		ts: boolean;
+	}
 }
 
 export interface SvelteOptions {