From 77f9de99aab6e0338737206b8bed61008ebf7fd6 Mon Sep 17 00:00:00 2001
From: Nic <162764842+Nic-Polumeyv@users.noreply.github.com>
Date: Sun, 6 Sep 2026 09:54:31 -0400
Subject: [PATCH] template expressions always go through the parser

---
 .../phases/1-parse/read/expression.js         | 125 ------------------
 1 file changed, 125 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/1-parse/read/expression.js b/packages/svelte/src/compiler/phases/1-parse/read/expression.js
index 1f8a051f47..e8f816a2b4 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/expression.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/expression.js
@@ -1,12 +1,8 @@
 /** @import { Expression, Identifier } from 'estree' */
 /** @import { Parser } from '../index.js' */
-import { isIdentifierStart, isIdentifierChar } from '@teasel/parser';
 import { parse_expression_at } from '../js.js';
-import { regex_whitespace } from '../../patterns.js';
 import * as e from '../../../errors.js';
 import { find_matching_bracket } from '../utils/bracket.js';
-import { is_reserved } from '../../../../utils.js';
-import { locator } from '../../../state.js';
 
 /**
  * @param {Parser} parser
@@ -37,9 +33,6 @@ export function get_loose_identifier(parser, opening_token) {
  * @returns {Expression}
  */
 export default function read_expression(parser, opening_token, disallow_loose, until) {
-	const simple = read_simple_expression(parser);
-	if (simple) return simple;
-
 	try {
 		const { node, end } = parse_expression_at(parser, parser.index, until);
 		parser.index = end;
@@ -57,121 +50,3 @@ export default function read_expression(parser, opening_token, disallow_loose, u
 		throw err;
 	}
 }
-
-const regex_non_lf_line_break = /\r(?!\n)|[\u2028\u2029]/;
-
-let last_template = '';
-let lf_only = true;
-
-/**
- * The parser breaks lines on bare `\r`, `\u2028` and `\u2029`, which the locator doesn't
- * @param {Parser} parser
- */
-function has_lf_line_breaks_only(parser) {
-	if (parser.template !== last_template) {
-		last_template = parser.template;
-		lf_only = !regex_non_lf_line_break.test(last_template);
-	}
-	return lf_only;
-}
-
-/**
- * Most template expressions are an identifier or a `a.b.c` member chain followed by `}`.
- * Those are built directly for better parse performance, with the same shape the parser would produce; anything else goes to the parser
- * @param {Parser} parser
- * @returns {Expression | null}
- */
-function read_simple_expression(parser) {
-	if (!has_lf_line_breaks_only(parser)) return null;
-
-	const template = parser.template;
-	const index = parser.index;
-
-	parser.allow_whitespace();
-	const start = parser.index;
-
-	let end = read_word(template, start);
-	if (end === -1 || is_reserved(template.slice(start, end))) {
-		parser.index = index;
-		return null;
-	}
-
-	/** @type {Expression} */
-	let node = identifier(template, start, end);
-
-	while (template[end] === '.') {
-		const property_end = read_word(template, end + 1);
-		if (property_end === -1) {
-			parser.index = index;
-			return null;
-		}
-
-		node = {
-			type: 'MemberExpression',
-			start,
-			end: property_end,
-			loc: { start: position(start), end: position(property_end) },
-			object: node,
-			property: identifier(template, end + 1, property_end),
-			computed: false,
-			optional: false
-		};
-
-		end = property_end;
-	}
-
-	parser.index = end;
-	parser.allow_whitespace();
-
-	if (!parser.match('}')) {
-		parser.index = index;
-		return null;
-	}
-
-	parser.index = end;
-	return node;
-}
-
-/**
- * @param {string} template
- * @param {number} start
- * @returns {number} the end of the identifier starting at `start`, or -1
- */
-function read_word(template, start) {
-	if (start >= template.length) return -1;
-
-	const code = /** @type {number} */ (template.codePointAt(start));
-	if (!isIdentifierStart(code)) return -1;
-
-	let end = start + (code <= 0xffff ? 1 : 2);
-
-	while (end < template.length) {
-		const code = /** @type {number} */ (template.codePointAt(end));
-		if (!isIdentifierChar(code)) break;
-		end += code <= 0xffff ? 1 : 2;
-	}
-
-	return end;
-}
-
-/**
- * @param {string} template
- * @param {number} start
- * @param {number} end
- * @returns {Identifier}
- */
-function identifier(template, start, end) {
-	return {
-		type: 'Identifier',
-		start,
-		end,
-		loc: { start: position(start), end: position(end) },
-		name: template.slice(start, end)
-	};
-}
-
-/** @param {number} index */
-function position(index) {
-	const { line, column } = locator(index);
-	return { line, column };
-}