[XeTeX] font selection debugging

[Jonathan Kew]

Hi Vladimir,

Sorry I have been so out-of-touch this week; very little connectivity  
at the TUG conference. :(

Looking back at your original report, which shows varying behavior for:

> \font\xxa="ArTarumianGrqiNor_U BoldItalic/I/ICU" at 10pt
> \edef\xxb{\fontname\xxa}
> \show\xxb
>
> when run on the first PC, i get:
>
>> \xxb=macro:
> ->"ArTarumianGrqiNor_U BoldItalic/ICU".
> l.3 \show\xxb
>
> when run on the secong PC, i get:
>
>> \xxb=macro:
> ->"ArTarumianGrqiNor_U Bold/ICU".
> l.3 \show\xxb

it seems to me that the first PC is showing the proper result. Is this  
the machine running the newer software versions? I suspect this might  
be a result of the different fontconfig versions:

> differences between the PCs are:
>
> 1) running xetex 0.999.1 (from current texlive Master tree) and  
> fontconfig 2.6.0 on debian sid
>
> 2) running xetex 0.997 (compiled on 2008-04-24) and  
> fontconfig-2.4.1-3.fc6

but it is also possible that it is due to xetex itself. Is it possible  
for you to try xetex 0.999.1 on PC 2, and 0.997 on PC 1, to see if the  
problem stays with the library or moves with xetex?

I'm thinking that to help with debugging things like this, maybe I  
should enhance \tracingfonts to support logging of the fontconfig  
queries and cache-building that xetex does. You can't easily debug  
merely with FC tracing at the moment, because of how xetex builds and  
uses its own cache; it does not simply execute a fontconfig query for  
the name that is given, so it's not comparable to running fc-match at  
the commend line.

JK