bug#57652: 29.0.50; Warning setting attribute of face ‘term’

[Akib Azmain Turja via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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David Ponce <da_vid@orange.fr> writes:

> On 08/09/2022 07:02, Po Lu wrote:
>> David Ponce <da_vid@orange.fr> writes:
>> 
>>> diff --git a/term.el b/term.el
>>> index 797fb18074..c564a5429a 100644
>>> --- a/term.el
>>> +++ b/term.el
>>> @@ -755,17 +755,19 @@ ansi-term-color-vector
>>>      term-color-bright-cyan
>>>      term-color-bright-white])
>>>
>>> -(defcustom term-default-fg-color nil
>>> -  "If non-nil, default color for foreground in Term mode."
>>> +(defcustom term-default-fg-color 'unspecified
>>> +  "Default color for foreground in Term mode."
>>>     :group 'term
>>> -  :type '(choice (const nil) (string :tag "color")))
>>> +  :type '(choice (const unspecified)
>>> +                 (string :tag "color")))
>> Doesn't that change behavior?
>> i.e. wouldn't it be better to test that term-default-fg-color is not
>> nil
>> wherever the face is actually made that color?
>
> To be honest I don't know.  I reread the spec that says:
>
>    "Apart from the values given below, each face attribute can have the
> value ‘unspecified’.  This special value means that the face doesn’t
> specify that attribute directly.  An ‘unspecified’ attribute tells Emacs
> to refer instead to a parent face (see the description ‘:inherit’
> attribute below); or, failing that, to an underlying face (*note
> Displaying Faces::).  (However, ‘unspecified’ is not a valid value in
> ‘defface’.)"
>
> So it seems that unspecified is not allowed in defface.  So, how to
> specify a missing attribute excepted by using nil in the defface used
> in term.el?
>
> (defface term
>   `((t
>      :foreground ,term-default-fg-color
>      :background ,term-default-bg-color
>      :inherit default))
>   "Default face to use in Term mode."
>   :group 'term)
>
> Thanks!
>
>
>
>

How about the following?

--8<---------------cut here---------------start------------->8---
(defface term
  `((t
     ,@(when term-default-fg-color
         '(:foreground ,term-default-fg-color))
     ,@(when term-default-bg-color
         '(:background ,term-default-bg-color))
     :inherit default))
  "Default face to use in Term mode."
  :group 'term)
--8<---------------cut here---------------end--------------->8---

It would not mention the attributes if the colors are nil.

-- 
Akib Azmain Turja

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