2027052 - svg <set attributeName="class"> not ending without inspect element

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[BZZZZ]

Attachment: svg <set> stuck.webm

Steps to reproduce:

1. open https://developer.mozilla.org/en-US/docs/Web/SVG/Reference/Element/set with firefox nightly (https://ftp.mozilla.org/pub/firefox/nightly/2026/03/2026-03-27-09-23-54-mozilla-central/firefox-151.0a1.en-US.linux-x86_64.tar.xz)
2. click black square
3. wait 2 seconds

Actual results:

black square becomes green circle and stays green circle

Expected results:

black square becomes green circle for 2 seconds

Comment 1

[Robert Longson [:longsonr]]

Would you be willing to use https://mozilla.github.io/mozregression/ to find a regression range? It's a pretty recent thing because it works in 149.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::SVG' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

[BZZZZ]

(In reply to Robert Longson [:longsonr] from comment #1)

Would you be willing to use https://mozilla.github.io/mozregression/ to find a regression range?

found by downloading and trying many nightly versions:

last good (black square becomes green circle for 2 seconds) nightly:
https://ftp.mozilla.org/pub/firefox/nightly/2026/03/2026-03-02-21-14-16-mozilla-central/firefox-150.0a1.en-US.linux-x86_64.tar.xz

first bad (black square becomes green circle and stays green circle) nightly:
https://ftp.mozilla.org/pub/firefox/nightly/2026/03/2026-03-03-09-56-35-mozilla-central/firefox-150.0a1.en-US.linux-x86_64.tar.xz

is https://mozilla.github.io/mozregression/ needed?

Comment 4

[Alice0775 White]

Regression window:
https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=507e7c73cc9bdd23ef5e7b69bebab29633b5d10b&tochange=8220ff0abb726c60b084a3b41d89660da46033c9

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

:emilio, since you are the author of the regressor, bug 2018671, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 6

[Robert Longson [:longsonr]]

Attachment: Bug 2027052 - Fix set end repaint r=emilio

Comment 7

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 2018671

Comment 8

[BZZZZ]

Attachment: multiple rect test.svg (click green)

note: firefox 148 is not also perfect (other elements get stuck)

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/1f9442396e61
https://hg.mozilla.org/integration/autoland/rev/3bed2de10f2e
Fix set end repaint r=emilio

Comment 10

[Emilio Cobos Álvarez [:emilio]]

Thanks Robert!

Comment 11

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/3bed2de10f2e

Comment 12

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: Fixes a recent regression when animating SVG elements.
• Code covered by automated testing?: yes
• Fix verified in Nightly?: yes
• Needs manual QE testing?: no
• Steps to reproduce for manual QE testing:
• Risk associated with taking this patch: low
• Explanation of risk level: reinstates some recently removed code that was thought not to be needed. Turns out that assesment was optimistic.
• String changes made/needed?: none
• Is Android affected?: yes

Comment 13

[Robert Longson [:longsonr]]

Attachment: Bug 2027052 - Fix set end repaint

Original Revision: https://phabricator.services.mozilla.com/D290577

Comment 14

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 2027052 - Fix style invalidation for SVG class attribute SMIL changes. r=longsonr

In the ClearAnimVal() codepath the snapshot is taken too late because
the GetAnimatedClassName() codepath checks IsAnimating(), which already
returns false.

Fix it by introducing WillAnimateClass(). Also, free the animated
classname when not animating anymore to avoid that check altogether.

Comment 15

[Phabricator Automation]

Comment on attachment 9560323 [details]
Bug 2027052 - Fix style invalidation for SVG class attribute SMIL changes. r=longsonr

Revision D290748 was moved to bug 2027540. Setting attachment 9560323 [details] to obsolete.

Comment 16

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot

Comment 17

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/656ab1666487
https://hg.mozilla.org/releases/mozilla-beta/rev/256522d4386c