bug#46436: 27.1.91; Font weight issue on MacOS Big Sur

[Robert Pluim]

>>>>> On Tue, 31 Aug 2021 20:22:04 +0100, Alan Third <alan@idiocy.org> said:

    Alan> Arnaud Antkowiak <arnaud.antkowiak@upmc.fr> writes:
    >> All the informations on font weight appear to be stripped out in Mac OS 
Big Sur ; as a result, a single weight takes precedence over the others.
    >> As an example, if I install say Roboto Mono Light, I can see the font 
via M-x describe-font as :
    >> 
    >> -*-Roboto Mono-bold-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-bold-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-normal-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-normal-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> 
    >> The ‘light’ weight information does not appear. As a consequence, if I 
now install Roboto Mono Regular, this is what I get:
    >> 
    >> -*-Roboto Mono-bold-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-bold-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-normal-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-normal-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> 
    >> The two fonts having the same handler, one takes precedence over the 
other (and all the text now appears as a long fat headline).
    >> Testing the same process under macOS Catalina (the previous OS) on 
another computer, this is what I get after installing Roboto Mono Light :
    >> 
    >> -*-Roboto Mono-bold-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-bold-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-normal-normal-*-14-*-*-*-m-0-fontset-auto1
    >> 
    >> And after installing Roboto Mono Regular :
    >> 
    >> -*-Roboto Mono-bold-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-bold-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-light-normal-normal-*-14-*-*-*-m-0-fontset-auto1
    >> -*-Roboto Mono-normal-italic-normal-*-*-*-*-*-m-0-iso10646-1
    >> -*-Roboto Mono-normal-normal-normal-*-*-*-*-*-m-0-iso10646-1
    >> 
    >> The font weight information is here preserved and I can select different 
variants of the font. So it seems like the problem really pertains to MacOS Big 
Sur.
    >> Many thanks in advance for your help,

    Alan> Hi, sorry nobody's got back to you before now.

    Alan> I don't have Big Sur installed so I can't test this.

    Alan> Are you able to try Emacs 28 (the master branch) and see if the 
problem
    Alan> exists there too?

Iʼm not sure. I installed those two fonts, and indeed when I select
'weight:light' in M-x customize-face it has no effect. But other than
that I donʼt see 'a long fat headline'.

Robert
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