Debugger crash where octal escape sequences exists

Why this is a good first issue

Debugger crashes with octal escape sequences but reproduction steps are unclear.

AI Summary

The debugger crashes when encountering octal escape sequences (\033) with a segmentation fault, though the issue cannot be reproduced in simple scenarios. The problem appears to be in V8's parser but requires deeper investigation into debugger-specific behavior.

Issue Description

Version

v25.6.1

Platform

Linux lenovo 6.18.9-arch1-2 #1 SMP PREEMPT_DYNAMIC Mon, 09 Feb 2026 17:16:33 +0000 x86_64 GNU/Linux

Subsystem

Debugger

What steps will reproduce the bug?

(the weird this is that I could not reproduce this using vscode debugging, or within a simple script)

I can't provide more info about my project (it's organizational) other than these screenshots from code

How often does it reproduce? Is there a required condition?

the required condition in my project is \033, I tried with \x1b, it does not crash.

happens always

What is the expected behavior? Why is that the expected behavior?

it should not crash

What do you see instead?

a crash with segmentation violation

Additional information

I could extract the backtrace using gdb and analyzing the core dump file:

#0  v8::internal::Variable::set_is_used (this=0x0) at ../deps/v8/src/ast/variables.h:87
#1  v8::internal::ParserBase<v8::internal::Parser>::UseThis (this=0x7ffc149672e0) at ../deps/v8/src/parsing/parser-base.h:1286
#2  v8::internal::Parser::ThisExpression (this=0x7ffc149672e0) at ../deps/v8/src/parsing/parser.h:791
#3  v8::internal::ParserBase<v8::internal::Parser>::ParsePrimaryExpression (this=0x7ffc149672e0) at ../deps/v8/src/parsing/parser-base.h:2195
#4  0x0000560c1fe2e62d in v8::internal::ParserBase<v8::internal::Parser>::ParseMemberExpression (this=0x7ffc149672e0) at ../deps/v8/src/parsing/parser-base.h:4159
#5  v8::internal::ParserBase<v8::internal::Parser>::ParseLeftHandSideExpression (this=0x7ffc149672e0) at ../deps/v8/src/parsing/parser-base.h:3881
#6  v8::internal::ParserBase<v8::internal::Parser>::ParsePostfixExpression (this=0x7ffc149672e0) at ../deps/v8/sr

GitHub Labels

v8 engine