1655661 - Korean text garbled, broken with Firefox 78.1.0esr, regression from 68.10.0esr, font WenQuanYi Micro Hei

Status: UNCONFIRMED

(Core :: Layout: Text and Fonts, defect)

Description

[lockywolf]

Attachment: 2020-07-28_Firefox-korean-bug-report_E7tpwqX.png

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

Set your main font to WenQuanYi Micro Hei (supports Latin, Cyrillic, Chinese, and other glyphs)

Search for Ggplot2 on www.bing.com

See broken Korean characters.
This problem is not present in Firefox 68.10.0esr.

When I have time, I would do a bisect.

Actual results:

Korean characters are displayed as gibberish.
(see screenshot)

Expected results:

Korean characters are displayed correctly.

Comment 1

[Daniel Holbert [:dholbert]]

(In reply to lockywolf from comment #0)

When I have time, I would do a bisect.

Thanks for the bug report & for offering to bisect -- this would help a lot with figuring what's going on & our next-steps here.

(If you're not already familiar with it, https://mozilla.github.io/mozregression/ is probably the tool you would want to use for bisecting.)

Comment 2

[Jonathan Kew [:jfkthame]]

This sounds very similar to bug 1534009, which was reported for a related font.

Comment 3

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

There no linked in this bug to reproduce. I tried "WenQuanYi Micro Hei", and the result is at bug 1534009 Comment 10.

Comment 4

[Bogdan Maris, Desktop Test Engineering]

I can't seem to be able to reproduce this issue using 78.1.0esr build on my linux machine after installing WenQuanYi Micro Hei font.

Comment 5

[lockywolf]

78.3.1esr still has this bug. Bisection is still planned, sorry about the delay.

Comment 6

[lockywolf]

The problem seems to have been reported in the past: https://sourceforge.net/p/wqy/bugs/42/

I emailed FangQ, asking him what to do.

I did try to bisect Firefox, but failed, the bisect copies all seem to display the text normally.
How exactly the "advance" metric used to be ignored in FF68, and is still ignored in the downloadable builds, but not ignored in the distribution versions, I do not know.