fix: allow whitespace before an after snippet parameters (#12159)

fixes #12156
Also remove obsolete code

packages/svelte/src/compiler/phases/1-parse/read/context.js

@@ -14,17 +14,16 @@ import { locator } from '../../../state.js';
 
 /**
  * @param {import('../index.js').Parser} parser
- * @param {boolean} [optional_allowed]
  * @returns {import('estree').Pattern}
  */
-export default function read_pattern(parser, optional_allowed = false) {
+export default function read_pattern(parser) {
 	const start = parser.index;
 	let i = parser.index;
 
 	const code = full_char_code_at(parser.template, i);
 	if (isIdentifierStart(code, true)) {
 		const name = /** @type {string} */ (parser.read_identifier());
-		const annotation = read_type_annotation(parser, optional_allowed);
+		const annotation = read_type_annotation(parser);
 
 		return {
 			type: 'Identifier',
@@ -84,7 +83,7 @@ export default function read_pattern(parser, optional_allowed = false) {
 			parse_expression_at(`${space_with_newline}(${pattern_string} = 1)`, parser.ts, start - 1)
 		).left;
 
-		expression.typeAnnotation = read_type_annotation(parser, optional_allowed);
+		expression.typeAnnotation = read_type_annotation(parser);
 		if (expression.typeAnnotation) {
 			expression.end = expression.typeAnnotation.end;
 		}
@@ -97,19 +96,12 @@ export default function read_pattern(parser, optional_allowed = false) {
 
 /**
  * @param {import('../index.js').Parser} parser
- * @param {boolean} [optional_allowed]
  * @returns {any}
  */
-function read_type_annotation(parser, optional_allowed = false) {
+function read_type_annotation(parser) {
 	const start = parser.index;
 	parser.allow_whitespace();
 
-	if (optional_allowed && parser.eat('?')) {
-		// Acorn-TS puts the optional info as a property on the surrounding node.
-		// We spare the work here because it doesn't matter for us anywhere else.
-		parser.allow_whitespace();
-	}
-
 	if (!parser.eat(':')) {
 		parser.index = start;
 		return undefined;

packages/svelte/src/compiler/phases/1-parse/state/tag.js

@@ -269,6 +269,8 @@ function open(parser) {
 			e.expected_identifier(parser.index);
 		}
 
+		parser.allow_whitespace();
+
 		const params_start = parser.index;
 
 		parser.eat('(', true);
@@ -289,6 +291,7 @@ function open(parser) {
 			parse_expression_at(prelude + `${params} => {}`, parser.ts, params_start)
 		);
 
+		parser.allow_whitespace();
 		parser.eat('}', true);
 
 		/** @type {ReturnType<typeof parser.append<import('#compiler').SnippetBlock>>} */

packages/svelte/tests/validator/samples/snippet-whitespace-ok/errors.json

@@ -0,0 +1 @@
+[]

packages/svelte/tests/validator/samples/snippet-whitespace-ok/input.svelte

@@ -0,0 +1,4 @@
+<!-- prettier-ignore -->
+{#snippet ok () }
+	asd
+{/snippet}