bug#39133: 28.0.50; Emacs slowdown on special char

[Robert Pluim]

>>>>> On Fri, 24 Jan 2020 12:22:38 +0200, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Robert Pluim <rpluim@gmail.com>
    >> Cc: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>,
    >> 39133@debbugs.gnu.org,  lg.zevlg@gmail.com,  handa@gnu.org
    >> Date: Fri, 24 Jan 2020 11:13:54 +0100
    >> 
    >> >>>>> On Wed, 15 Jan 2020 18:19:28 +0200, Eli Zaretskii <eliz@gnu.org> 
said:
    Eli> We could do in the 'else' branch the same we do in the single caller
    Eli> of this function, fill_gstring_body, when we don't call
    Eli> font_fill_lglyph_metrics:
    >> 
    >> Rather than duplicate that code, I moved the FONT_INVALID_CODE check
    >> up. This works for me:

    Eli> Looks reasonable, thanks.

Except it crashes under -nw. More investigation required.

Robert