bug#45920: 28.0.50; set-face-attribute cannot read :family when different :weight exist

bug#45920: 28.0.50; set-face-attribute cannot read :family when different :weight exist

[Protesilaos Stavrou]

Dear maintainers,

I have noticed that setting fonts via 'set-face-attribute' works as
intended except in the following scenario (on 'emacs -Q'):

   ;; Sample 1
   (set-face-attribute 'default nil
                       :family "Source Code Pro"
                       :weight 'light)

   ;; Sample 2
   (set-face-attribute 'default nil
                       :family "Hack"
                       :weight 'normal)

If you evaluate sample 1, you will get the desired behaviour.  Namely,
the font family for the default face is the one specified, as is the
typographic weight.

Now if you proceed to evaluate sample 2, you will notice that only the
weight gets updated.  The family continues to be that of sample 1.

At this point, to get the family of sample 2, you need to evaluate
sample 2 one more time.

I tried various combinations and my impression is that the problem
occurs when the :weight properties are different.  Other properties,
such as :height, do not exhibit this behaviour.

Can you reproduce this on your end?

All the best,
Protesilaos

-- 
Protesilaos Stavrou
protesilaos.com

bug#45920: 28.0.50; set-face-attribute cannot read :family when different :weight exist

[Eli Zaretskii]

> From: Protesilaos Stavrou <info@protesilaos.com>
> Date: Sat, 16 Jan 2021 22:09:54 +0200
> 
>    ;; Sample 1
>    (set-face-attribute 'default nil
>                        :family "Source Code Pro"
>                        :weight 'light)
> 
>    ;; Sample 2
>    (set-face-attribute 'default nil
>                        :family "Hack"
>                        :weight 'normal)
> 
> If you evaluate sample 1, you will get the desired behaviour.  Namely,
> the font family for the default face is the one specified, as is the
> typographic weight.
> 
> Now if you proceed to evaluate sample 2, you will notice that only the
> weight gets updated.  The family continues to be that of sample 1.
> 
> At this point, to get the family of sample 2, you need to evaluate
> sample 2 one more time.
> 
> I tried various combinations and my impression is that the problem
> occurs when the :weight properties are different.  Other properties,
> such as :height, do not exhibit this behaviour.

I didn't try to reproduce, because I don't have one of these fonts.
However, it might be relevant that when you call set-face-attribute
with several attributes related to the face's font, the underlying
primitive, internal-set-lisp-face-attribute, is called multiple time,
one time for every attribute.  So the order of those calls might
matter, especially if one of the fonts doesn't support some of the
values of all the attributes (e.g., the 'normal' weight in this case).

bug#45920: 28.0.50; set-face-attribute cannot read :family when different :weight exist

[Protesilaos Stavrou]

On 2021-01-16, 22:25 +0200, Eli Zaretskii <eliz@gnu.org> wrote:

>> From: Protesilaos Stavrou <info@protesilaos.com>
>> Date: Sat, 16 Jan 2021 22:09:54 +0200
>> 
>>    ;; Sample 1
>>    (set-face-attribute 'default nil
>>                        :family "Source Code Pro"
>>                        :weight 'light)
>> 
>>    ;; Sample 2
>>    (set-face-attribute 'default nil
>>                        :family "Hack"
>>                        :weight 'normal)
>> 
>> If you evaluate sample 1, you will get the desired behaviour.  Namely,
>> the font family for the default face is the one specified, as is the
>> typographic weight.
>> 
>> Now if you proceed to evaluate sample 2, you will notice that only the
>> weight gets updated.  The family continues to be that of sample 1.
>> 
>> At this point, to get the family of sample 2, you need to evaluate
>> sample 2 one more time.
>> 
>> I tried various combinations and my impression is that the problem
>> occurs when the :weight properties are different.  Other properties,
>> such as :height, do not exhibit this behaviour.
>
> I didn't try to reproduce, because I don't have one of these fonts.
> However, it might be relevant that when you call set-face-attribute
> with several attributes related to the face's font, the underlying
> primitive, internal-set-lisp-face-attribute, is called multiple time,
> one time for every attribute.  So the order of those calls might
> matter, especially if one of the fonts doesn't support some of the
> values of all the attributes (e.g., the 'normal' weight in this case).

Thank you Eli for the prompt reply!

Following your input, I tried alternating between those two and they
both give me the right results:

   (progn
     (internal-set-lisp-face-attribute 'default :family "Source Code Pro" 0)
     (internal-set-lisp-face-attribute 'default :weight 'light 0))
   
   (progn
     (internal-set-lisp-face-attribute 'default :weight 'normal 0)
     (internal-set-lisp-face-attribute 'default :family "Hack" 0))

Please feel free to close this.

-- 
Protesilaos Stavrou
protesilaos.com

bug#45920: 28.0.50; set-face-attribute cannot read :family when different :weight exist

[Eli Zaretskii]

> From: Protesilaos Stavrou <info@protesilaos.com>
> Cc: 45920@debbugs.gnu.org
> Date: Sat, 16 Jan 2021 23:02:24 +0200
> 
> Following your input, I tried alternating between those two and they
> both give me the right results:
> 
>    (progn
>      (internal-set-lisp-face-attribute 'default :family "Source Code Pro" 0)
>      (internal-set-lisp-face-attribute 'default :weight 'light 0))
>    
>    (progn
>      (internal-set-lisp-face-attribute 'default :weight 'normal 0)
>      (internal-set-lisp-face-attribute 'default :family "Hack" 0))
> 
> Please feel free to close this.

Done.