2008688 - [regression] Clockwise / Counterclockwise can be mirrored by scale transform when the font does not support rtlm

Status: RESOLVED FIXED

(Core :: MathML, defect)

Description

[Frédéric Wang Nélar]

Attachment: rtl-contour-integral.html

See the attached testcase. The clockwise contour integral in RTL mode is mirrored to an anticlockwise contour, which incorrectly changes semantic.

I believe this is due to this code, which unconditionally fallback to a scale transform:

https://searchfox.org/firefox-main/rev/33bba5cfe4a89dda0ee07fa9fbac578353713fd3/layout/mathml/nsMathMLChar.cpp#1391

Or when mathml.rtl_operator_mirroring is disabled, to this line:

https://searchfox.org/firefox-main/rev/33bba5cfe4a89dda0ee07fa9fbac578353713fd3/layout/mathml/nsMathMLChar.cpp#1655

I don't think it's a regression from bug 945183 but I rather suspect bug 1789583, where clockwise/anticlockwise contour integrals entries in mathfont.properties got the "mirrorable" property added.

Anyway, after bug 945183 we still need to keep them mirrorable via r t l m, but forbid mirroring via a scale transform.

I don't know if there are similar clockwise/anticlockwise operators that shouldn't be mirrored by a scale transform.

Comment 1

[Frédéric Wang Nélar]

Attachment: rtl-contour-integral.html

Comment 2

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1789583

Comment 3

[eri]

It makes sense to disable the mirroring when it changes semantics. I did add both lines you mentioned, but they were targeted at keeping square roots and other similar symbols mirrored when rtlm wasn't available. I agree that clockwise contour integrals shouldn't be a part of that.

Comment 4

[eri]

Attachment: Bug 2008688 - Prevent mirroring unsupported characters by scale transform when font doesn't support rtlm. r?fredw,emilio

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/4657f4c8a655
https://hg.mozilla.org/integration/autoland/rev/4a16c1262b03
Prevent mirroring unsupported characters by scale transform when font doesn't support rtlm. r=emilio,layout-reviewers

Comment 6

[amarc]

https://hg.mozilla.org/mozilla-central/rev/4a16c1262b03

Comment 7

[BugBot [:suhaib / :marco]]

Since nightly and release are affected, beta will likely be affected too.
For more information, please visit BugBot documentation.

Comment 8

[BugBot [:suhaib / :marco]]

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

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox149 to wontfix.

For more information, please visit BugBot documentation.

Comment 9

[eri]

I don't think it is so important to require an uplift, likely not many users are affected. It doesn't seem like I have permission to modify the bug. Could you set the status to wontfix if you agree, @fredw?

Comment 10

[Frédéric Wang Nélar]

You can probably ask permission so you can set flags yourself: https://bugzilla.mozilla.org/page.cgi?id=get_permissions.html