1863779 - Invalid CSS abs() subtraction

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect, P2)

Description

[[:bali balo]]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:121.0) Gecko/20100101 Firefox/121.0

Steps to reproduce:

transform: translateX(calc(100px - abs(100px)));

Example JSFiddle: https://jsfiddle.net/d4zk3has/

Actual results:

The element is translated by 200px to the right, as if the following was used:
calc(100px + abs(-100px))

Expected results:

The element should not be translated horizontally (the result of the operation should be 0px).

A current workaround is to multiply by -1:
calc(100px + -1 * abs(100px))

Comment 1

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

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

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Indeed, negate() for Abs is incorrect here. Tiaan, do you have cycles to look? Presumably we can just wrap_in_negate. Let me know if not and I can look myself.

Kind of surprised no tests fail due to this.

Comment 3

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

Set release status flags based on info from the regressing bug 1838600

Comment 4

[Tiaan Louw]

Attachment: Bug 1863779 - abs() function should not negate its child r=emilio,#layout

The abs() function is not distributive, so should be wrapped in a negate
node rather than negating its child during simplification. E.g.:

10 - abs(10) != 10 + abs(-10)

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f90b853d9b0b
abs() function should not negate its child r=emilio,layout-reviewers

Comment 6

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

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/43078 for changes under testing/web-platform/tests

Comment 7

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/f90b853d9b0b

Comment 8

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

Upstream PR merged by moz-wptsync-bot

Comment 9

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

The patch landed in nightly and beta is affected.
:tlouw, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox120 to wontfix.

For more information, please visit BugBot documentation.