Re: problems with face-spec-reset-face and set-face-attribute

[Richard M. Stallman]

    1. The statement about the behavior of nil and t for set-face-attribute is
    apparently not true for attribute :inherit, but it is true for the other
    attributes. The doc for set-face-attribute specifically mentions support for
    :inherit, without saying anything special about it.

It is supposed to be true for all attributes.
Why do you say this is not true for :inherit?

Perhaps there is a bug.

    2. Apparently, the set-face-attribute behavior also depends on what value
    the attribute is set to: setting it to (pseudo-)value nil changes (resets)
    its default value for future frames; setting it to another value apparently
    does not.

If this is true, it is a bug.  It is supposed to affect future frames
when FRAME is nil or t.  Otherwise it should never do so.

    3. The value `unspecified' is not very clear to me, but I don't have time
    now to look up where it is documented. A default value of `unspecified', by
    its _name_, would seem like it should have the behavior that apparently only
    nil gives. Or is that just for :inherit?

This is documented in the Lisp manual.  Is that documentation clear?
If not, could you point out what in the Lisp manual is unclear?

If you find a case whose behavior does not match the manual,
could you please report that as a bug?

    4. set-face-attribute is implemented with internal-set-lisp-face-attributes.
    That internal function has the clearest doc string of the three! Its
    treatment of nil and t is different (and somewhat backward) from their
    treatment by set-face-attribute: nil means change the attribute for the
    selected frame; t means change its default value, for new frames; 0 means
    change its value on all existing frames and its default value for new
    frames. nil for set-face-attribute translates to 0 for internal-set*; t
    remains t; a real frame is passed along.

It is somewhat unclean that internal-set-lisp-face-attributes
does not follow the same convention as set-face-attribute,
but since internal-set-lisp-face-attributes is not meant for users,
it is not a real problem.

    6. What is the point (use case) of face-spec-reset?

I don't see any face-spec-reset in frame.el.
Do you mean face-spec-reset-face?

It is meant for use by face-spec-set.

    And I don't see :inherit mentioned anywhere as an exception.

That's because it isn't one.

    And I don't see nil mentioned in its special role for default (future)
    values, although that might be done somewhere else in the doc.

That's because it does not have such a role.