Invalid regex is not shown to be invalid

[DasJott]

Issue Type: Bug

This regex: ([^?]+)\?([^:]+)\:(.*) is supposed to find lines like the following:
res = foo?bar:baz.
Instead it states: "No results"

I was told this exact same condition works under Windows. Both most recent versions, but different Electron versions. Maybe that's the thing?

regex tester

VS Code version: Code 1.43.2 (0ba0ca5, 2020-03-24T07:52:11.516Z)
OS version: Linux x64 5.4.27-1-MANJARO

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz (4 x 3500)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: disabled_software skia_renderer: disabled_off_ok video_decode: unavailable_off viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	2, 2, 1
Memory (System)	15.36GB (0.88GB free)
Process Argv
Screen Reader	no
VM	0%

[jrieken]

/needsMoreInfo

Is that inside the editor or global search?

[myfonj]

Backslash (\) before : should not be necessary in this context, and in this case removing it makes it work in text search. It seems like a discrepancy compared to standard RegExp we know from JavaScript, where backslash-escaping non-control characters usually makes no difference:

/a/.test('a') // true
/\a/.test('a') // true

In VSC text search it makes a difference:

Version: 1.43.2.

Commit: 0ba0ca52957102ca3527cf479571617f0de6ed50
Date: 2020-03-24T07:38:38.248Z
Electron: 7.1.11
Chrome: 78.0.3904.130
Node.js: 12.8.1
V8: 7.8.279.23-electron.0
OS: Windows_NT x64 10.0.16299

---

(I'm not sure but I think that regex engine used for document and file text search is not "just vanilla JS" (ripgrep perhaps?), and I'm not even sure if 100% compatibility with JS regex peculiarities is a goal. Nice bug anyway, good catch!)

[DasJott]

It is regarding text search within the editor. Didn't try the global one.
I also already tried with backslash removed but never got it. I sense that the problem is in the not operator like [^?]. Exchanging that to a simple .* worked as expected.

[myfonj]

I also already tried with backslash removed but never got it.
I sense that the problem is in the [negated character class] [^?]+. Exchanging that to a simple .* worked as expected.

So in your case just removing the extra backslash from \: (resulting in regexp ([^?]+)\?([^:]+):(.*)) yielded different outcome than expected? You had to further alter the negated character class or something?

It works for me, and I'd not expect this will be platform dependent:

[DasJott]

Well, the same setting worked on Windows, but not in Linux.

[alexdima]

The JS engine throws when constructing the regular expression:

[alexdima]

Removing the unicode flags makes the regex valid: new RegExp('\\a', 'ig') works.

I think the validation code (that would display an error) forgets to use the unicode flag.