From 9f54a36de3f5138dceab1ba5e179d6d8234d18f3 Mon Sep 17 00:00:00 2001
From: sapphi-red <49056869+sapphi-red@users.noreply.github.com>
Date: Sun, 16 Nov 2025 09:25:13 +0000
Subject: [PATCH] fix(semantic): error on `\00` in strict mode (#15743)

`\00` matches LegacyOctalEscapeSequence and should be an error in strict mode.
https://tc39.es/ecma262/2025/multipage/ecmascript-language-lexical-grammar.html#sec-string-literals-early-errors
---
 crates/oxc_semantic/src/checker/javascript.rs | 2 +-
 tasks/coverage/misc/fail/escape-00.js         | 1 +
 tasks/coverage/snapshots/parser_misc.snap     | 9 ++++++++-
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 tasks/coverage/misc/fail/escape-00.js

diff --git a/crates/oxc_semantic/src/checker/javascript.rs b/crates/oxc_semantic/src/checker/javascript.rs
index 13cae88b0b719..7c3cb018c85d3 100644
--- a/crates/oxc_semantic/src/checker/javascript.rs
+++ b/crates/oxc_semantic/src/checker/javascript.rs
@@ -361,7 +361,7 @@ pub fn check_string_literal(lit: &StringLiteral, ctx: &SemanticBuilder<'_>) {
             if c == '\\' {
                 match chars.next() {
                     Some('0') => {
-                        if chars.peek().is_some_and(|c| ('1'..='9').contains(c)) {
+                        if chars.peek().is_some_and(char::is_ascii_digit) {
                             return ctx.error(legacy_octal(lit.span));
                         }
                     }
diff --git a/tasks/coverage/misc/fail/escape-00.js b/tasks/coverage/misc/fail/escape-00.js
new file mode 100644
index 0000000000000..efe2ff4022144
--- /dev/null
+++ b/tasks/coverage/misc/fail/escape-00.js
@@ -0,0 +1 @@
+export const escape00 = "\00";
diff --git a/tasks/coverage/snapshots/parser_misc.snap b/tasks/coverage/snapshots/parser_misc.snap
index f62eaa207b68b..6621d34be164e 100644
--- a/tasks/coverage/snapshots/parser_misc.snap
+++ b/tasks/coverage/snapshots/parser_misc.snap
@@ -1,7 +1,7 @@
 parser_misc Summary:
 AST Parsed     : 49/49 (100.00%)
 Positive Passed: 49/49 (100.00%)
-Negative Passed: 112/112 (100.00%)
+Negative Passed: 113/113 (100.00%)
 
   × Cannot assign to 'arguments' in strict mode
    ╭─[misc/fail/arguments-eval.ts:1:10]
@@ -72,6 +72,13 @@ Negative Passed: 112/112 (100.00%)
         If you're in the middle of a rebase, the top section is the code being rebased onto and the bottom section is the code coming from the current commit being rebased.
         If you have nested conflicts, resolve the outermost conflict first.
 
+  × '0'-prefixed octal literals and octal escape sequences are deprecated
+   ╭─[misc/fail/escape-00.js:1:25]
+ 1 │ export const escape00 = "\00";
+   ·                         ─────
+   ╰────
+  help: for octal literals use the '0o' prefix instead
+
   × Expected `,` or `]` but found `const`
    ╭─[misc/fail/imbalanced-array-expr.js:2:1]
  1 │ const foo = [0, 1