bug#59507: 29.0.50; Autoloads generation hangs on Windows and Emacs 29

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 22 Nov 2022 20:13:47 +0000
> From:  Denys Mentiei via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> It looks like "loaddefs-generate--file-load-name" hangs when it receives
> a path starting with "c:/".
>  
> Looking at the code, it seems like the very first loop, which
> eats the path piece by piece with (file-name-directory name) never
> terminates as (file-name-directory-name "c:/") returns "c:/".

Thanks.

I may be missing something, but I fail to see the difference between a
Windows file name starting with "C:/" and a Unix file name starting with
"/", as far as that function is concerned.  Either they both work or they
both fail in the same way, because (file-name-directory "/") returns "/".

So do you have a real-life recipe where loaddefs-generate--file-load-name is
called and infloops?  Can you show such a recipe, preferably in "emacs -Q"?

Alternatively, a recipe which just invokes loaddefs-generate--file-load-name
with file names which cause the loop will also suffice, but in that case
please also describe how did those file names ended up being passed to the
function, i.e. with which file/directory names did the call sequence start.

The reason I'm asking is that I'm not yet sure whether the problem, whatever
it is, is in the function you pointed to or in some other place.