Cosmetic class filters beginning with a number getting discarded

[yourduskquibbles]

Prerequisites

• [ ] I verified that this is not a filter issue
  • Filter issues MUST be reported at filter issue tracker
• [ ] This is not a support issue or a question
  • Support issues and questions are handled at /r/uBlockOrigin
• [ ] I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
• I tried to reproduce the issue when...
  • [ ] uBlock Origin is the only extension
  • [ ] uBlock Origin with default lists/settings
  • [ ] using a new, unmodified browser profile
• [ ] I am running the latest version of uBlock Origin
• [ ] I checked the documentation to understand that the issue I report is not a normal behavior

Description

Class filter beginning with a number get thrown out as invalid.

From logger:

Discarded Easylist filter:

Test Filters added by me:

A specific URL where the issue occurs

Update Easylist or test in My Filters with test.com##.1-abp & test.com##.2-abp

Steps to Reproduce

1a. Update Easylist or 1b. Add test filters to My Filters test.com##.1-abp & test.com##.2-abp

2. View invalid filter in logger

Expected behavior:

Class Filters beginning with a number are parsed and used.

Actual behavior:

Class filters beginning with a number get thrown out

Your environment

• uBlock Origin version: uBlock Origin 1.25.3b1
• Browser Name and version: Firefox nightly 76.0a1 (2020-03-10) (64-bit)
• Operating System and version: Windows 10 1909 (64-bit)

[uBlock-user]

https://github.com/orgs/uBlockOrigin/teams/ublock-issues-volunteers/discussions/167?from_comment=6#discussion-167-comment-6

[gwarser]

This is better: https://github.com/orgs/uBlockOrigin/teams/ublock-issues-volunteers/discussions/167?from_comment=5#discussion-167-comment-5

The problem is the selector .123tv-ads is not valid. That filter is from EasyList:

123tvnow.com##.123tv-ads

As per CSS character escape sequences:

If the first character of an identifier is numeric, you’ll need to escape it based on its Unicode code point. For example, the code point for the character 1 is U+0031, so you would escape it as \000031 or \31 .

Basically, to escape any numeric character, just prefix it with \3 and append a space character ( ). Yay Unicode!

So this would work:

123tvnow.com##.\31 23tv-ads

This needs to be fixed in EasyList.

[gwarser]

ABP "Picker" correctly escapes classes.

AdBlock for Chrome creates Attribute Selector.

Both require escaping to work.