Re: texinfo 6.0 texindex problem?

[Eli Zaretskii]

> Date: Thu, 8 Oct 2015 21:08:11 +0100
> From: Gavin Smith <address@hidden>
> Cc: Texinfo <address@hidden>
> 
> There is a new syntax for specifying an explicit sort key that was
> introduced after the Texinfo 6.0 release. It looks like
> 
> @cindex @sortas{\ escape sequence} \ (backslash), escape sequence
> 
> Here "\ (backslash), escape sequence" is the text that will be output
> in the index, and "\ escape sequence" is the sort key.

Btw, my usual problem with such new features is that it's impossible
(AFAIK) to use them in a manual in a backward-compatible way,
i.e. while making sure older versions of makeinfo will process the
manual without errors.  That's because there's no way (again AFAIK) to
write a condition that tests whether a given feature is available, nor
even one that tests the version of makeinfo that is processing the
file.

This forces any real-world project to avoid using the newly introduced
features completely, until enough years pass after their introduction,
because telling the end users to install the latest Texinfo is not a
practical option.

So perhaps we should introduce a facility for such tests, and
preferably in a way that is itself backward-compatible, e.g., testable
with @ifset or some such.