Random orange-ish rectangles

[b1t-ninja]

Describe the bug
When I run freeze file.swift it produces an image which always contains at least one orange-red rectangle that appears in the first 3 lines of code.

Here's an example

If the file is just 3 lines of code it works fine.

To Reproduce
Steps to reproduce the behavior:

1. Create .swift file and put

typealias PartOne = @Sendable (String) -> Int
@available(macOS 13.0, *)
let partOne: PartOne = { x in
  let digitPattern = /\d+/ // -- 1
  
  return x.split(separator: "\n").reduce(0) { acc, curr in // -- 2
    let matches = curr.matches(of: digitPattern) // -- 3
    guard let first = Int(matches.first!.0) else { return acc } // -- 3
    
    return acc + first + (matches.count > 1 ? Int(matches.last!.0)! : 0) // -- 4
  }
}

inside
3. run freeze file.swift
4. Tada !

Expected behavior
There should be an output image freeze.png

Desktop (please complete the following information):

• OS: macOS Sequoia 15.1.1

[bashbunni]

I was able to reproduce this as well on master. I also tested the svg output (freeze file.swift -o freeze.svg) and it didn't have this issue (attached)

Will have to take a look at the png conversion under the hood. Thanks for reporting this and providing us with steps to repro!

[prithvijj]

Just adding random comments:

I tried running the same code on Windows (go run . lol.swift), and while freeze.png looks okay,

When I tried running it with go run . lol2.swift -o freeze.svg and adding extra regexes ( maybe this is regice lol?),
it seems the red rectangles pops up, specifically for \d \n, but not for the /(.+?): (.+)/

and the red rectangle does seem to come from the style defined here

freeze/style.go

Line 10 in 2d7c398

chroma.Error: "#F1F1F1 bg:#F05B5B",

Desktop:

• OS: Windows 10

[prithvijj]

And seems like when parsing, the \ token? shows that it's an Error Type which is why the red color #F05B5B comes in

Running this in .vscode/launch.json

{
    "version": "0.2.0",
    "configurations": [
      {
        "name": "Debug Go Run",
        "type": "go",
        "request": "launch",
        "mode": "debug",
        "program": "${workspaceFolder}",
        "args": ["lol2.swift", "-o", "freeze.svg"],
        "showLog": true
      }
    ]
  }
  

[prithvijj]

And seems like when writing a similar-ish code for typescript

// lol2.ts

const digitPattern = /\d+/; // -- 1

and running go run . lol2.ts -o freeze.svg, seems like it's able to figure out the regex type is LiteralStringRegex (3114), (i.e. doesn't render any error, and doesn't draw the rectangle box)

which looks like it's been defined at
https://github.com/alecthomas/chroma/blob/79621af0ab93bb11ac72b35d97893b8787cd52c2/lexers/embedded/typescript.xml#L184-L187

Meanwhile swift.xml doesn't have anything related to LiteralStringRegex or regex typing in that sense, which might be causing the red rectangle to show up since it's an "Error"

https://github.com/alecthomas/chroma/blob/master/lexers/embedded/swift.xml

[arut-plus]