Edit message composer has superfluous escaping

[germain-gg]

Steps to reproduce

1. Send matrix-react-sdk/res/themes/light/css/_light.scss as message in Element
2. Hit the up arrow to edit the message

Outcome

What did you expect?

To see the edit message composer appear and prefilled with matrix-react-sdk/res/themes/light/css/_light.scss

What happened instead?

Notice the incorrect escaping before the underscore

Operating system

No response

Browser information

No response

URL for webapp

No response

Application version

No response

Homeserver

No response

Will you send logs?

No

[robintown]

It's not incorrect, just unnecessary, so will mark this as tolerable

[germain-gg]

I disagree with the triaging here. The escaping is incorrect. My message does not contain those backslash and to a non technical user this will look out of place

It could even make them move the cursor to delete those characters which is a big ask

[t3chguy]

@gsouquet that's a whole class of bugs

#22342
element-hq/element-meta#1493
#10808

[anoadragon453]

Also chiming in with my own instance of this while editing a message. The editing composer showed an extra backslash, whereas the original message only contained one:

Event source

{
  "type": "m.room.message",
  "content": {
    "org.matrix.msc1767.message": [
      {
        "body": "\\",
        "mimetype": "text/plain"
      },
      {
        "body": "\\",
        "mimetype": "text/html"
      }
    ],
    "body": "\\",
    "msgtype": "m.text",
    "format": "org.matrix.custom.html",
    "formatted_body": "\\"
  }
}

Looking at the event source, I'm confused why body has two backslashes...

[t3chguy]

Looking at the event source, I'm confused why body has two backslashes...

Otherwise it'd be escaping the " and breaking JSON

https://www.freeformatter.com/json-escape.html

Backslash is replaced with \

[anoadragon453]

Otherwise it'd be escaping the " and breaking JSON

Ahhh, duh, right.

I suppose the blame does still lie with the edit composer field displaying \\ to the user then.

[t3chguy]

Yeah so that is just the re-escaping code being naive and not checking if the escaping is necessary

[babolivier]

Worth noting it affects more than just what the sender sees in the composer, as it can also affect code blocks, as seen in one of the supporter rooms earlier this week:

(since escaping backlashes aren't automagically hidden in code blocks)

[robintown]

@babolivier Please open a separate issue for that, so we can keep this one focused on the benign cases of unnecessary escaping. Incidentally, I can't reproduce that issue, so please provide repro steps if you can.

[babolivier]

Please open a separate issue for that, so we can keep this one focused on the benign cases of unnecessary escaping. Incidentally, I can't reproduce that issue, so please provide repro steps if you can.

Sorry I completely missed this comment. iirc I was reporting an issue with a message that @anoadragon453 sent. I cannot seem to be able to repro it either. So I'll let Andrew open a new issue if it happens again.

[anoadragon453]

I'm not able to reproduce the issue in your comment at this point @babolivier.

I can still reproduce the one in the message editing composer as shown here however.

Element Desktop Nightly 2022090801, Arch Linux.