[lltx] bug in the caches

[Elie Roux]

Hello,

I just spent some time debugging the error I had in luaotfload. It came 
from something I wasn't expecting: In the cache of the font, the 
filename is wrong because I moved the font. The problem is that 
specification.filename is not taken into account at all if there is a 
filename in the cache, even if this filename leads to no file.

Hans, do you think you could change the files to fix this problem? (If 
I'm not wrong and if the problem has not already been fixed since the 
last time we sync, which is very recent).

If not (this is more for the lualatex team), I thought about two solutions:
  - we could free the font cache when we call mkluatexfontdb, this would 
reset everything and it would be doable by the user in case of bug (that 
could appear later)
  - I can patch the ConTeXt files to check the filename, but it will be 
a bit more difficult to maintain...
  - we can do both!

Also I just discovered something: if fc-list cannot be executed (which 
is likely to be the case for TeXLive 2010) and the font database is 
regenerated during a tex compilation, the font database will loose all 
the OS fonts... I think the best way to fix this is not to save the 
database if fc-list cannot be executed, and print a warning message 
telling the user that a font has not been found and if it should have, 
to launch mkluatexfontdb.

I just spotted another problem (that we can postpone): the .pk files are 
always regenerated, even when they can be found... I'll try to fix the 
problem soon.

Thank you,
-- 
Elie