Robert Pluim <rpluim@gmail.com> writes:

Hi Robert,

>>>>>> On Tue, 04 Feb 2020 13:15:48 +0100, Robert Pluim <rpluim@gmail.com> said:
>     Robert> This is from 'emacs -Q' as well? One thing you could do is run

Yes, emacs -Q is the same.

>     Robert> FC_DEBUG=15 emacs -Q

Wow, that's large.  I uploaded it here:

  https://send.firefox.com/download/c5f0f5318f936032/#OGuNHBWhZCZHTCW0TV2YDA

>     Robert> which will output debug on what FontConfig is trying to do. The
>     Robert> jetbrains font is using iso8859-1 rather than iso10646-1, perhaps
>     Robert> there is some influence from locale settings?

I don't know.  I use a en_US.UTF-8 locale with some German unit
exceptions here.

➜ locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC=de_DE.UTF-8
LC_TIME=de_DE.UTF-8
LC_COLLATE="en_US.UTF-8"
LC_MONETARY=de_DE.UTF-8
LC_MESSAGES="en_US.UTF-8"
LC_PAPER=de_DE.UTF-8
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT=de_DE.UTF-8
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=

> One other thing to try is M-: (setq font-log nil) before you create
> the second frame, and then look at the value of font-log afterwards.

That's the value after changing the font, setting it to nil and opening
a new frame.