[luatex] [tex-live] Ignored italic correction with lua(la)tex format

[Philipp Stephani]

2011/10/6 Khaled Hosny <khaledhosny at eglug.org>:
> Hi all,
>
> After a long night of debugging and hair pulling, I finally found why
> italic correction for OpenType math fonts is ignored in luatex and
> lualatex formats but not in context.
>
> For some reason not yet clear to me, the setting of catcode to 11 in
> luatex-unicode-letters.tex causes luatex to not apply italic correction
> (might be related to the fact that luatex applies IC selectively).
>
> This minimal example shows the issues:
>
> \input luaotfload.sty
> \font\xits={file:xits-math.otf} at 10pt
> \textfont0=\xits
> $$\Umathchar"7"0"1D443\Umathchar"4"0`($$
> \bye
>
> after commenting the \catcode part in line 18 of
> luatex-unicode-letters.tex and rebuilding the format, italic correction
> is applied.
>
> I'm not sure what is the proper fix here, though.

LuaTeX explicitly removes italic correction after letters:

            if (is_new_mathfont(cur_f) && get_char_cat_code(cur_c) == 11) {
                *delta = 0;     /* no italic correction in mid-word of
text font */
	    }

This seems like a bug to me.