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TextMate tokenizer enters incorrect scope after typeof a < "u" in JavaScript, affecting subsequent function declarations #1076
Description
VS Code Version
Version: 1.124.2 (user setup)
Commit: 6928394f91b684055b873eecb8bc281365131f1c
Date: 2026-06-12T00:12:36Z
Electron: 42.2.0
ElectronBuildId: 14159160
Chromium: 148.0.7778.97
Node.js: 24.15.0
V8: 14.8.178.14-electron.0
OS: Windows_NT x64 10.0.26200
Fresh install of VS Code with all default settings. No extensions installed, no custom configuration applied.
Also reproduced on VS Code for the Web (vscode.dev) with no extensions or custom configuration.
Reproducible Example
function bar() {
return "bar";
}
var a = typeof a < "u";
function foo() {
return "foo";
}Steps to Reproduce
- Install VS Code with all default settings (no extensions, no custom configuration).
- Create a new
.jsfile. - Paste the code above.
- Run:
Developer: Inspect Editor Tokens and Scopes
- Inspect the first
functionkeyword (bardeclaration). - Inspect the second
functionkeyword (foodeclaration).
Actual Result
The first function declaration is tokenized correctly:
storage.type.function.js
meta.function.js
source.js
The second function declaration is tokenized incorrectly:
entity.name.type.js
meta.type.parameters.js
meta.var.expr.js
source.js
Syntax highlighting becomes incorrect for all code following:
var a = typeof a < "u";Expected Result
The second function declaration should receive the same scopes as the first:
storage.type.function.js
meta.function.js
source.js
No tokenizer state should leak past the end of the variable declaration.
Additional Investigation
Replacing:
var a = typeof a < "u";with:
var a = typeof a > "u";
immediately fixes the issue. The second `function` is then correctly scoped as:
Notes
- Reproduced on a fresh VS Code install with all default settings and no extensions.
- Reproduced across all built-in themes; the issue is not theme-specific.
- The JavaScript is syntactically valid.
Activity
mohityadav8 commentedon Jun 14, 2026
/assign
can i work on this
RedCMD commentedon Jun 14, 2026
should report to the upstream grammar repo https://github.com/microsoft/TypeScript-TmLanguage
this should be fixable
otherwise it can be mitigated by adding a bunch of safeguards to
typeto stop it from going past brackets)and semicolons;etctho why are you trying to do this?
typeof a < "u"is there a real world example that's bothering you?
mohityadav8 commentedon Jul 16, 2026
/working
soeyu commentedon Jul 27, 2026
RedCMD (@RedCMD)
I don't normally write code in this style myself. However, I sometimes inspect bundled code, and after running it through a formatter/beautifier, I discovered this issue.
RedCMD commentedon Jul 27, 2026
makes sense
is that example directly from a bundle (beautified)?
or did you hand write it?
soeyu commentedon Jul 28, 2026
you can find the <`u` pattern directly in this bundled file:
https://chatgpt.com/cdn/assets/2340486e-gh6s19h8ofjisiyk.js
I discovered this issue when beautifying the code in VS Code with Prettier or Oxcfmt.