bug#2807: Subject: 23.0.90; etags can't access .el.gz files

[Stefan Monnier <monnier@iro.umontreal.ca>]

>>> (".info.xz"   . "unxz")
>>> (".info"      . nil)
>>> ("-info.Z"    . "uncompress")
>>> ("-info.Y"    . "unyabba")
>> 
>> Yes.
>> 
>>> etc etc etc.  Is this even necessary in Info?
>> 
>> It's just as necessary as it is for etags: without it, Info won't find
>> the compressed files.
>> 
>>> Doesn't jka-compr know all about this already?
>> 
>> jka-compr knows how to decompress the main ones, yes.  But not all of
>> them, and (more importantly) it doesn't know how to look for them.

> Sorry; I was unclear.  I meant: Doesn't jka-compr know how to uncompress
> all these files already?

As I said it "knows how to decompress the main ones, yes".

> And if not -- why not?

It doesn't do all of them because ... I don't know why.  My guess is
that there's a subtle risk of jka-compr applying when it shouldn't, so
we prefer to only use it when we're pretty sure the name implies it is
a compressed file.

> Finding the files is a different issue, and since the file name list
> contains "info" in all the names, there isn't much potential for reuse
> by etags.

Wholesale reuse, no, indeed.  But the compression-extension part, yes.

> So I would suggest writing some code in jka-compr that would allow
> jka-compr to look for compressed files, too (given a regexp), and then
> etags could use that, and info.el could be converted (after Emacs 24.1)
> to use that, too.

That sounds right.


        Stefan