Several web pages which display monospaced text (but not all) fail to render the text at all. This happens on https://www.snoyman.com/blog/2017/12/stack-and-nightly-breakage (all the code text) and on http://drdr.racket-lang.org/ (all the text in all but the left-most column). This is on 59.0a1 (2017-12-05) (64-bit) on Ubuntu Linux, and only appeared with the 12/5 Nightly.

This looks typical of some sandbox-related font issues we've seen, but they are supposed to have been fixed. If you go to about:config and set security.sandbox.content.level down to 2, and then restart the browser, does that make any difference?

That did not fix it. For good measure I tried 0 as well, but that didn't change anything either.

OK, thanks -- in a way it's reassuring, actually, to know it wasn't a recurrence of that problem. What font is (supposedly) being used for the elements that fail to render, if you check with the DevTools inspector? (Look at its Fonts panel to see what is reported as actually used, as opposed to what's specified in the CSS font-family property.)

The fonts panel says: Courier New system Used as: "Courier New" The CSS is: font-family: Courier New, Courier, monospace; That's for drdr.racket-lang.org.

OK, what kind of font is the Courier New you have installed? Running fc-match -v "Courier New" in a terminal should dump a whole bunch of details about it.

Here's the output: https://gist.github.com/3c127880e4239b167deffe77661a51c0

On a different machine (also Ubuntu) the same build does not have the problem, here's the `fc-match` output there: https://gist.github.com/4d945ecae9b6a5c4df5e3bb3802a0995 The diff is (courier-new has the bug): [samth@hermes:/tmp plt] diff -u courier.out courier-new.out --- courier.out 2017-12-07 14:48:36.605693895 -0500 +++ courier-new.out 2017-12-07 14:49:12.577737390 -0500 @@ -1,4 +1,4 @@ -Pattern has 36 elts (size 48) +Pattern has 38 elts (size 48) family: "Courier New"(s) familylang: "en"(s) style: "Regular"(s) "Normal"(s) "obyčejné"(s) "Standard"(s) "Κανονικά"(s) "Normaali"(s) "Normál"(s) "Normale"(s) "Standaard"(s) "Normalny"(s) "Обычный"(s) "Normálne"(s) "Navadno"(s) "thường"(s) "Arrunta"(s) @@ -12,8 +12,9 @@ pixelsize: 12.5(f)(s) spacing: 100(i)(w) foundry: "Mono"(w) + antialias: True(w) hintstyle: 1(i)(w) - hinting: True(s) + hinting: True(w) verticallayout: False(s) autohint: False(s) globaladvance: True(s) @@ -52,6 +53,7 @@ fontformat: "TrueType"(w) embeddedbitmap: True(s) decorative: False(s) + lcdfilter: 1(i)(w) namelang: "en"(s) prgname: "fc-match"(s) postscriptname: "CourierNewPSMT"(w)

OK, so this is the truetype Courier New from the MS core fonts collection. Lee, any idea why it would be failing to render on one of these systems (where LCD antialiasing is enabled, apparently)?

Are you using WebRender?

Ah, yes, that's it. Turning off webrender fixes the problem. What should I do to get more webrender debug info?

Can't reproduce @ Debian Testing, KDE, Radeon RX480. Btw your tabs (Github, Bugzilla) are showing WebRender bug 1418718.

I suspect this is a manifestation of the same problem in bug 1422408. The WebRender update on Dec 5 fixed a bug that prevented embedded bitmaps from loading. So if things render fine without embedded bitmaps, that indicates the font has scalable outlines in it AND embedded bitmaps, and we're choosing the wrong ones. I will fix bug 1422408 first and we can reevaluate if this one is fixed.

Is this fixed now in the latest nightly?

This appears to be fixed. Thanks!