1815936 - Flexbox with `align-items: last baseline` has nonsensical results

Status: VERIFIED FIXED

(Core :: Layout: Flexbox, defect)

Description

[David Shin[:dshin]]

Attachment: flex-last-baseline.html

STR: Load attached test case
Expected: left side's black border box aligns with the flex container's bottom box
Actual: left side's box protrudes over the top of the flex container

We're calling GetNaturalBaselineBOffset which returns the baseline from the block end as origin, which is incompatible with the rest of the code which takes block start as the origin.

Comment 1

[David Shin[:dshin]]

Attachment: Bug 1815936 - In flexbox baseline calculation, ensure that the offset originates from border-start. r=dholbert

GetNaturalBaselineBOffset returns the offset originating from border-end for
last baselines.

Comment 2

[Daniel Holbert [:dholbert]]

Looks like the problematic code-snippet came from me in bug 1672640, btw. Adding a dependency.

(This isn't exactly a regression from that bug, because our layout was wrong before, too -- when I view this testcase in builds before bug 1672640's fix, we place the left box a little too far down, below the bottom of the right boxes. Hence, just using dependency flags.)

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3f46184524f1
In flexbox baseline calculation, ensure that the offset originates from border-start. r=dholbert

Comment 4

[Iulian Moraru]

Backed out for causing wpt failures on flex-align-baseline-flex-001.html.

• Push with failures

• Failure log

• Backout link

[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - TEST-PASS | /css/css-flexbox/alignment/flex-align-baseline-flex-001.html | .target > * 4 
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - TEST-FAIL | /css/css-flexbox/alignment/flex-align-baseline-flex-001.html | .target > * 5 - assert_equals: 
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - <div data-offset-y="35"><span></span></div>
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - offsetTop expected 35 but got 15
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - assert_tolerance@http://web-platform.test:8000/resources/check-layout-th.js:24:22
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - checkExpectedValues@http://web-platform.test:8000/resources/check-layout-th.js:87:25
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - checkSubtreeExpectedValues@http://web-platform.test:8000/resources/check-layout-th.js:7:44
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - window.checkLayout/</<@http://web-platform.test:8000/resources/check-layout-th.js:228:34
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:2591:25
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - test@http://web-platform.test:8000/resources/testharness.js:628:30
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - window.checkLayout/<@http://web-platform.test:8000/resources/check-layout-th.js:221:13
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - window.checkLayout@http://web-platform.test:8000/resources/check-layout-th.js:220:29
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - onload@http://web-platform.test:8000/css/css-flexbox/alignment/flex-align-baseline-flex-001.html:1:12
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - TEST-PASS | /css/css-flexbox/alignment/flex-align-baseline-flex-001.html | .target > * 6 
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - TEST-UNEXPECTED-PASS | /css/css-flexbox/alignment/flex-align-baseline-flex-001.html | .target > * 7 - expected FAIL
[task 2023-02-17T19:26:17.125Z] 19:26:17     INFO - TEST-INFO | expected FAIL
[task 2023-02-17T19:26:17.129Z] 19:26:17     INFO - 
[task 2023-02-17T19:26:17.129Z] 19:26:17     INFO - TEST-PASS | /css/css-flexbox/alignment/flex-align-baseline-flex-001.html | .target > * 8 

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2a4e00d6502a
In flexbox baseline calculation, ensure that the offset originates from border-start. r=dholbert

Comment 6

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/2a4e00d6502a

Comment 7

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Reproducible on a 2023-02-20 Nightly build on Windows 10.
Verified as fixed on Firefox 112.0b7(build ID: 20230326180212) and Nightly 113.0a1(build ID: 20230327093043) on Windows 10, macOS 12, Ubuntu 22.