KDE Plasma 5: fonts in taskbar rendered as blocks [SOLVED]

[pbarill]

Once in a while I try again KDE Plasma 5, to see if this time it has become acceptable (last time I tried it would not keep a screen configuration between sessions!!). It's been out for 4 years today!!

Problem du jour: Some fonts are displayed in a way that could not be read, like mere blocks instead of characters, especially in the taskbar.

Hard to say when the problem started, as I did not touch plasma5 in a long time. That was a few weeks ago (system up to date as of about June 6). After updating a bunch of kde stuff it's still there. Actually, it got worst: I can't see anymore what's written on the left pane of System Settings (screenshot taken before this).

This screenshot:
https://imagebin.ca/v/48pcGhdovCq5

Setting different size/font in System Settings does not make a difference.

Hopefully others ran into this… Suggestions?

Got everything up to date as of yesterday (Jul 14). This is stable x86.

kde-plasma/plasma-desktop 5.12.5-r1
x11-drivers/xf86-video-intel 2.99.917_p20180214-r1

Graphic card: same as day 1 on this laptop, unexciting Intel integrated something something.

[ct85711]

Typically, when font shots up as strange characters or blocks, it is often one of 3 things.

First, the language doesn't have the requested character code (i.e. UFT-8 wasn't set).
Second, the system is trying to use a language that it isn't setup for (i.e. the system wants to use French, when only English is set).
Third, the requested font isn't available to use.

Now, from what you mentioned, the 3rd option is unlikely since you changed fonts and didn't help. Anymore, UTF-8 is becoming more common, and a standard thing to have set.
The first thing to check, is make sure you have UTF-8 is enabled for each language you have set (don't forget to run locale-gen after you make a change in locale.gen, to generate the character sets). It is safe, if you run locale-gen anyways to ensure all of the locale been generated.

Also give the output from running locale, to show what the default locale to use.

I saw it mentioned that kde does/did store a config with the locale to use in it's configs, but I am not certain if/where it is right off hand. (Configs saved by gnome and kde has been known to cause issues when you update the system.)

[pbarill]

Thanks for giving this some thoughts.

I managed to solve the problem.

My dirty little secret: Most packages on this machine are built on another machine, which is not the same `march` (of course I do set the right target `march` and cpu flags when building binary package). I did that for a few years without problem, though some never successfully built that way (such as gcc, for obvious reasons if you are familiar with its build process).

Why do that? Because it's fun! Actually because the target machine is a not so powerful i3 laptop, and building hundreds of packages for many hours sounds like a punishment. I got this pretty good desktop (2500km away) with loads of memory that I use to build stuff.

After gcc 4.x, the list of things which would not merge using this scheme got longer, and now it seems there are a few that go through and give headaches, even if I set the target march as 'generic' (that's not normal, right?).

So on that target machine I went on to rebuild a bunch of x11 and font related packages, qtcore, kwin and plasma related one. No effect. Then just tried all of qt,