Special characters are escaped in headings when they shouldn't be

[SethFalco]

Steps to reproduce

1. Have a chat open
2. Have the other party send one of the following messages if they're on Element, if not on Element then a message that produces the same source:

#

{
  "type": "m.room.message",
  "content": {
    "org.matrix.msc1767.message": [
      {
        "body": "# <(^-^<)",
        "mimetype": "text/plain"
      },
      {
        "body": "<h1>&lt;(^-^&lt;)</h1>\n",
        "mimetype": "text/html"
      }
    ],
    "body": "# <(^-^<)",
    "msgtype": "m.text",
    "format": "org.matrix.custom.html",
    "formatted_body": "<h1>&lt;(^-^&lt;)</h1>\n"
  }
}

/html <h1>&lt&semi;(^-^&lt&semi;)</h1>

{
  "type": "m.room.message",
  "content": {
    "org.matrix.msc1767.message": [
      {
        "body": "<h1>&lt;(^-^&lt;)</h1>",
        "mimetype": "text/plain"
      },
      {
        "body": "<h1>&lt;(^-^&lt;)</h1>",
        "mimetype": "text/html"
      }
    ],
    "body": "<h1>&lt;(^-^&lt;)</h1>",
    "msgtype": "m.text",
    "format": "org.matrix.custom.html",
    "formatted_body": "<h1>&lt;(^-^&lt;)</h1>"
  }
}

Outcome

What did you expect?

Android devices should unescape special characters first before rendering the heading. For example, on Element Desktop and on GitHub it'll look like this:

<(^-^<)

What happened instead?

The less-than (<) symbols aren't unescaped, so the < from when the content was converted to HTML is used literally and the user actually sees this:

&lt;(^-^&lt;)

A screenshot from the Android device:

Your phone model

Fairphone 4

Operating system version

Android

Application version and app store

No response

Homeserver

one.ems.host

Will you send logs?

No

Are you willing to provide a PR?

Yes

[paulvt]

I am not sure what you mean with "headings" but it happens in normal messages too.

Just send some text from Element Android with an ampersand in it. It will appear as & when rendered in the timeline.

[SethFalco]

I don't use Android, so I only know about the issue that was screenshotted and shared with me. Headings refers to using Markdown to create a heading.

# This is a Heading!

This is a Heading!

[effbiae]

Yeah, this happens in half my messages, too:

[tulir]

Duplicate of #6445

[SethFalco]

Hmm, I'll make my wife check for updates and check this out again. If the bug is resolved, I'll close the issue.

[ouchadam]

thanks for raising! this is indeed #6445 and was fixed as part of 1.4.28