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Regular Expression Syntax Highlighting only recognising control characters if uppercase #1063
Description
Type: Bug
\cJand\cjare equivalent
The syntax highlighter in VSCode only puts the uppercase form in blue, seemingly recognising \c as a separate escape and j as a normal character.
It would be good to show both forms in blue.
VS Code version: Code 1.106.3 (bf9252a2fb45be6893dd8870c0bf37e2e1766d61, 2025-11-25T22:28:18.024Z)
OS version: Darwin arm64 24.6.0
Modes:
System Info
| Item | Value |
|---|---|
| CPUs | Apple M4 (10 x 2400) |
| GPU Status | 2d_canvas: enabled direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: enabled_on trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off |
| Load (avg) | 2, 3, 3 |
| Memory (System) | 24.00GB (0.13GB free) |
| Process Argv | --crash-reporter-id 25a900f1-fd90-425a-8691-a245dd6d0743 |
| Screen Reader | no |
| VM | 0% |
Extensions (21)
| Extension | Author (truncated) | Version |
|---|---|---|
| markdown-mermaid | bie | 1.29.0 |
| vscode-eslint | dba | 3.0.16 |
| docker | doc | 0.18.0 |
| githistory | don | 0.6.20 |
| gitlens | eam | 17.7.1 |
| prettier-vscode | esb | 11.0.2 |
| copilot-chat | Git | 0.33.4 |
| vscode-github-actions | git | 0.28.1 |
| vscode-containers | ms- | 2.3.0 |
| vscode-docker | ms- | 2.0.0 |
| playwright | ms- | 1.1.17 |
| debugpy | ms- | 2025.16.0 |
| python | ms- | 2025.18.0 |
| vscode-pylance | ms- | 2025.10.4 |
| vscode-python-envs | ms- | 1.12.0 |
| remote-explorer | ms- | 0.5.0 |
| remote-server | ms- | 1.5.3 |
| vscode-jest | Ort | 6.4.4 |
| code-spell-checker | str | 4.3.2 |
| svelte-vscode | sve | 109.12.0 |
| explorer | vit | 1.36.0 |
A/B Experiments
vsliv368cf:30146710
pythonvspyt551:31249599
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31334701
aj953862:31281341
nes-set-on:31351930
6abeh943:31336334
cloudbuttont:31379625
todos-1:31405332
qwen_all_req:31402696
42190218_ostrepl:31403339
trigger-command-fix:31379601
auto_model_enabled:31385282
use-responses-api:31390855
je187915:31401257
ec5jj548:31422691
copilot-nes-oct-t:31418199
terminalsuggestenabled:31426255
cmp-ext-treat:31426748
cp_cls_c_966_ss:31426491
defaultvisibility:31426295
expandedtokens:31427242
copilot6169-t:31426761
c0683394:31419495
3fia6346:31426581
478ah919:31426797
2bd77578_control:31426889
fa76a614:31426880
5j92g670_sonnet:31426787
406hc587_ask_agent:31428393
Activity
RedCMD commentedon Dec 6, 2025
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_expressions/Character_classes#types states only capital letters
tho lower case does work
symbols are treated as liberals
/\c@/matches the literal\c@(even tho the backslash should technically be escaped itself)should move issue to upstream grammar repo https://github.com/microsoft/TypeScript-TmLanguage
I will provide a fix in my own extension shortly
https://marketplace.visualstudio.com/items?itemName=RedCMD.regexp-syntax-highlighter
TomStrepsil commentedon Dec 7, 2025
p.s. if useful, here's the definition of the modulo behaviour in the ECMA spec:
TomStrepsil commentedon Dec 7, 2025
Have raised mdn/content#42273
Fix lowerCaseControlCharacters
RedCMD commentedon Dec 9, 2025
fixed in my extension
before:
after:
commit: RedCMD/regex-syntax-highlighter-vscode@ef3c44e#diff-dcc2f871f0fa04ceb3b9e4bc88f3d4db3de22e6570989029a6a76002613a27a3