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bug#18573: 24.3.93; set-face-attribute crashes Emacs when started with -
bug#18573: 24.3.93; set-face-attribute crashes Emacs when started with -nw
Mon, 29 Sep 2014 20:18:11 +0300
> From: Jan Djärv <address@hidden>
> Date: Sun, 28 Sep 2014 10:44:15 +0200
> Cc: address@hidden
> This seems to be a generic error in xfaces.c. It tries to load a font
> without checking the type
> of frame. The type is tty, but it tries to load a font anyway, and
> eventually ends up in (font.c) font_pixel_size, which does:
> #define FRAME_RES_Y(f) \
> (eassert (FRAME_WINDOW_P (f)), FRAME_DISPLAY_INFO (f)->resy)
> Now, FRAME_DISPLAY_INFO for a NS compiled Emacs is
> #define FRAME_DISPLAY_INFO(f) ((f)->output_data.ns->display_info)
> but the frame is not an NS frame, it is a tty frame, so bad things happen.
> It is the same for X, but there it just happens to return a nonsense value,
> so the code continues without crashing, and eventually discovers that there
> are no font dirvers and the load font fails.
> The code is in xfaces.c, Finternal_set_lisp_face_attribute, around line 3120
> where it calls
> The code in question is not called if compiled for a tty (#ifdef:ed out), but
> it is called when the frame is a tty frame on a non-tty compiled Emacs.
> I think these cases should be the same, i.e. font_load_for_lface not called
> for tty frames.
I believe this happens when internal-set-lisp-face-attribute is
called with its FRAME argument t, meaning change the default for new
(i.e. future) frames. Since the code needs a frame, it just uses the
selected frame, which in this case happens to be a TTY frame.
Is that description correct?
If so, the question is how to fix this. If we simply do nothing when
the selected frame is a TTY frame, and then create a GUI frame at some
future point, will the new default take effect? If it will, then I
agree that the code under this condition
if (! FONT_OBJECT_P (value))
should not be executed when the selected frame is a TTY frame.
But if this doesn't work, then what are our alternatives? We could
loop over all the frames looking for a GUI frame, and use that. But
what if there's no such frame? Signal an error?