Re: Note on e65c307 breaks font-height

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 27 May 2016 15:18:02 +0200
> From: martin rudalics <rudalics@gmx.at>
> 
>  > What exactly is in your .emacs file? That is, can you give a recipe to reproduce the problem?
> 
> It's reproducible here with my
> 
> (custom-set-faces
>   ;; custom-set-faces was added by Custom.
>   ;; If you edit it by hand, you could mess it up, so be careful.
>   ;; Your init file should contain only one such instance.
>   ;; If there is more than one, they won't work right.
>   '(default ((t (:stipple nil :background "grey92" :foreground "black" :inverse-video nil :box nil :strike-through nil :overline nil :underline nil :slant normal :weight normal :height 98 :width normal :foundry "outline" :family "Courier New")))))

Any reasons why you prefer specifying each of the font's attributes
separately, instead of just specifying a font?  IOW, how is the above
different from something like

  (add-to-list 'default-frame-alist '(font . "-outline-Courier New-normal-r-normal-normal-15-112-96-96-c-90-iso8859-1"))

(in your case, you may wish changing the size numbers, I think)?

The advantage of the full font specification is that it works around
the subtleties of the Emacs font selection procedure, whereby it could
effectively disregard some of the attributes as result.

> My analysis so far is as follows: In ‘font-setting-change-default-font’
> the disjunct (frame-parameter f 'font-parameter) always evaluates to
> nil here.  Before your patch, the disjunct
> 
> 		 (or (font-get (face-attribute 'default :font f 'default)
> 			       :user-spec)

Why are we looking at the :font attribute, when you say the
problematic attribute is :height?

Anyway, I think the best way forward is to debug Emacs during startup,
putting a breakpoint where the :height attribute is being processed,
and see what happens before and after Paul's change of the :user-spec
symbol's definition.  (My guess is that the change is correct, and the
problems it uncovers are either unrelated bugs, or something that
isn't supposed to work in the first place, at least not reliably.)