:watch-attr() stopped working

[gwarser]

Details

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

MajkiIT/polish-ads-filter#18147 (comment)

Does not work on test page: https://ameshkov.github.io/web/watchattr.html

A specific URL where the issue occurs

https://ameshkov.github.io/web/watchattr.html

Steps to Reproduce

1. Add ameshkov.github.io###testdiv:watch-attr(id):has(p)
2. Visit https://ameshkov.github.io/web/watchattr.html
3. Click on button

Expected behavior:

Element should appear/disapper after click on button

Actual behavior:

Element does not appear

Your environment

• uBlock Origin version: bisected
• Browser Name and version: Firefox Nightly, Chrome 87.0.4280.88
• Operating System and version: Manjaro KDE

Notes

Broken in 1.29.3.9

[rdk@on uBlock-git]$ git bisect bad && ./tools/make-chromium.sh 
35aefed92616cbfb75f12f37c7ea7fb3a3cc3369 is the first bad commit
commit 35aefed92616cbfb75f12f37c7ea7fb3a3cc3369
Author: Raymond Hill <rhill@raymondhill.net>
Date:   Mon Sep 7 08:28:01 2020 -0400

    Add support to chain `:style()` to procedural operators
    
    Related issue:
    - https://github.com/uBlockOrigin/uBlock-issues/issues/382
    
    Additionally, remnant code for pseudo-user stylesheets
    has been removed. Related commit:
    - https://github.com/gorhill/uBlock/commit/5c68867b92735931a791dfedf4ef9608cc364862

 platform/chromium/vapi-background.js     |  23 ++-
 platform/chromium/vapi-client.js         |   8 +-
 src/js/background.js                     |   4 +-
 src/js/contentscript.js                  | 278 ++++++++++++-------------------
 src/js/cosmetic-filtering.js             | 167 ++++++-------------
 src/js/epicker-ui.js                     |  17 +-
 src/js/scriptlets/cosmetic-logger.js     |   6 +-
 src/js/scriptlets/dom-inspector.js       |  23 ++-
 src/js/scriptlets/dom-survey-elements.js |   4 +-
 src/js/scriptlets/epicker.js             | 180 ++++++--------------
 src/js/static-filtering-parser.js        |  43 +++--
 11 files changed, 281 insertions(+), 472 deletions(-)
*** uBlock0.chromium: Creating web store package
*** uBlock0.chromium: copying common files
*** Packaging assets in dist/build/uBlock0.chromium/assets... rm: cannot remove 'dist/build/uBlock0.chromium/assets/ublock/resources.txt': No such file or directory
done.
*** uBlock0.chromium: Generating meta...
*** uBlock0.chromium: Package done.
[rdk@on uBlock-git]$ 

[gorhill]

This was causing a regression not only for :watch-attr but also for any case of elements no longer matching any procedural filters.

[gorhill]

Now the question: is it a case of emergency fix for a 1.31.4 release?

[krystian3w]

Maybe just disable for few weeks this filter: uBlockOrigin/uAssets@6b78f43

[gwarser]

It's surprising it was broken for so long and no one noticed.

Is it still broken for normal "elements" case? https://gwarser.github.io/web/watchattr.html https://ameshkov.github.io/web/watchattr.html (updated)

[gwarser]

What the... It works if I click on second test button and then on first test button.

[krystian3w]

Yeah, works as you wrote.

Maybe similar:

goodie.pl and filter:

goodie.pl##body > div[class]:last-of-type:has(a[href="/ochrona-danych"])

• uBo DOM inspector sometimes lie what element is hidden: goodie.pl MajkiIT/polish-ads-filter#18146 (comment) - on few PC-s procedural filters stock on loaded #body-wrapper (hidding possible detect only by devtools).

• for few seconds #body-wrapper is :last-child / :last-of-type.

[gorhill]

Yeah, I see the filterer is not informed of removed nodes, I will have to figure out why this changed. It seems the DOM watcher's code was modified and this broke reporting of removed DOM nodes.

---

I will have to find the exact commit for this change but I think my thinking was to avoid firing DOM changes when non-element nodes are removed, for example when just a text node is removed. So when I optimized for this I actually broke reporting DOM changing as a result of elements being removed.

---

This broke in gorhill/uBlock@6112a68#diff-7c975d431b3d370b6b59f5860b06ddfdfc44eeafc32ef49dd705b13be13446ed, Oct 2017...