bug#15138: Font selection error on OSX

[Kenichi Handa]

In article <B1058569-FA76-4B76-84DF-46A38916008F@swipnet.se>, Jan Djärv 
<jan.h.d@swipnet.se> writes:

> I've made a fix for this in the trunk, please try it.

Do you mean this change?

        * fontset.c (face_for_char): Check char in the current face font first
        if HAVE_NS (Bug#15138).

I agree that this change improves font selection for
symbols, but it's not good for many scripts for which just
having a glyph is not enough.  For instance, if the default
font has Hindi glyphs but doesn't have the OTF features for
Hindi script, we must find another proper font for Hindi.

How about modifying the current fontset mechanism as this?

(1) Allow t for FONT-SPEC of set-fontset-font to tell that
    the default font should be tried.
(2) Modiyf the default fontset to include `t' as the
    font-spec for scripts/characters for which the default
    font is ok.

---
Kenichi Handa
handa@gnu.org