From 3eca26584dc26947f4efcd7626ac5e0f3f8bd859 Mon Sep 17 00:00:00 2001
From: Natalie Weizenbaum <nweiz@google.com>
Date: Wed, 11 Aug 2021 01:52:17 +0000
Subject: [PATCH] Fix a single-backslash attribute selector (#1428)

Closes #1423
---
 CHANGELOG.md              | 3 +++
 lib/src/parse/parser.dart | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ce37bab8..f1c4d2e6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 ## 1.37.6
 
+* Fix a bug where quotes would be omitted for an attribute selector whose value
+  was a single backslash.
+
 * Allow `if` to be used as an unquoted string.
 
 * Properly parse backslash escapes within `url()` expressions.
diff --git a/lib/src/parse/parser.dart b/lib/src/parse/parser.dart
index da0aeae7..271d1d80 100644
--- a/lib/src/parse/parser.dart
+++ b/lib/src/parse/parser.dart
@@ -441,7 +441,7 @@ class Parser {
     var value = 0;
     var first = scanner.peekChar();
     if (first == null) {
-      return "";
+      scanner.error("Expected escape sequence.");
     } else if (isNewline(first)) {
       scanner.error("Expected escape sequence.");
     } else if (isHex(first)) {