Re: [help-texinfo] No index in PDF manual

[Gavin Smith]

On Wed, Apr 03, 2019 at 04:18:28PM -0600, Karl Berry wrote:
>     At least omitting the index makes the problem clear, instead of some TeX 
>     error message being output when the user tries to run TeX, 
> 
> Wouldn't an error message be highly desirable as well as omission?
> 
> It is pretty easy not to notice that no index was generated. Few
> authors, me included, are in the habit of checking whether a tool did
> its job if no error is reported. Mere messages on the console are too
> easily ignored. --best, karl.

Okay, it may be better to have a harder failure to encourage people to 
upgrade, instead of having subtle degradation.

However, a hard failure on a sorted index file starting with a 
backslash breaks the automatic upgrade when texi2dvi is run:

* A Texinfo file has already been processed and index files using 
backslashes exist
* texi2dvi runs TeX, the sorted index files in the old format are ignored
and unsorted index files in the new format are created
* texi2dvi sees that the index files have changed (since they now use @ 
signs), so runs texindex, creating new sorted index files
* texi2dvi runs TeX again and this time the sorted index files are 
typset as indices.

This could be fixed by having the new texi2dvi detect the old sorted 
index files and deleting them.  Or possibly texi2dvi could keep on going 
after TeX exits with an error, if the index files have changed.