Code Highlighting Broken for Generic Functions with Default Values in .tsx Files

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#1,042 opened on Oct 25, 2024 4 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 38/100

Issue type: Bug
Clarity: Mostly clear
Activity status: Stale
Tech stack: typescript
Domain: tooling

Research direction

Reproduce the example in a .tsx file and compare its highlighting with the same code in a .ts file. Inspect the TypeScript TextMate grammar rules for generic parameters with default values and arrow functions; done means the .tsx colors match the expected TypeScript highlighting without affecting the existing .ts behavior.

Written by the indexing model from the issue text.

Description

Does this issue occur when all extensions are disabled?: Yes

Version: 1.95.0-insider
Commit: 804f450ca900d24db25e7174e8b6dfb3fb2a318c
Date: 2024-10-22T13:30:10.100Z
Electron: 32.2.1
ElectronBuildId: 10427718
Chromium: 128.0.6613.186
Node.js: 20.18.0
V8: 12.8.374.38-electron.0
OS: Darwin x64 24.0.0

Describe the bug
In VSCode, when writing a generic function with default values in a .tsx file, code highlighting is broken and colors are displayed incorrectly. The same code works fine in a .ts file.

To Reproduce

Open VSCode and create a new .tsx file.
Write the following code:

const func = <T = string,>(args: T): string => {
  const t = typeof args;
  if (typeof t === 'string') {
    return t.split(',').join('_');
  }
  return '';
};
func('');

const add = (a: number, b: number) => {
  return a + b;
};

Observe the code highlighting.

Expected behavior
Code highlighting should work correctly and match the behavior in .ts files.

Screenshots
In .tsx file:

Pay attention to the screenshot where the generic default parameter definitions, colons, and arrow function arrows are all highlighted in red, while the colors of keywords such as const, if, and return are incorrect.

In .ts file:

Dominant language: TypeScript
Stars: 471
Forks: 149
PR merge metrics: No merged PRs in 30d

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