Re: bidi properties from uniprop tables

[Eli Zaretskii]

> From: "Stephen J. Turnbull" <address@hidden>
> Cc: Kenichi Handa <address@hidden>,
>     address@hidden
> Date: Fri, 19 Aug 2011 13:44:48 +0900
> 
>  > I made the code in bidi.c defensive about what it gets from the
> 
> Maybe that should be an assert, since a null return is an Emacs bug.

There's already something that catches such problems, albeit
indirectly, and aborts -- that's how I found this in the first place.
However, it doesn't make sense to have an assert where the bidi
property of a character is looked up as long as we don't make sure
this doesn't happen "normally", because having such an assert now will
cause a predictable crash when moving in a buffer created by
describe-categories.  People use the development version for their
day-to-day work, you know...

>  > uniprop table, but the question is, should we do something to never
>  > have nil in Lisp or zero in C return from these APIs?
> 
> Yes, a non-nil property list is required by the standard for all code
> points

It's not a property list, it's a single property whose value is a
symbol that shouldn't be nil.  See get-char-code-property.