Re: How do I best identify and delete stale .eln files?

[Eli Zaretskii]

> Date: Sat, 10 May 2025 18:07:35 +0000
> Cc: emacs-devel@gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> Hello, Eli.
> 
> Thanks for the rapid reply.
> 
> On Sat, May 10, 2025 at 20:21:06 +0300, Eli Zaretskii wrote:
> > > Date: Sat, 10 May 2025 17:07:54 +0000
> > > From: Alan Mackenzie <acm@muc.de>
> 
> > > Hello, Emacs.
> 
> > > On my (GNU) system I've got over 1.2 GB of .eln files.  Listing them
> > > shows that many of these must be stale, since there are several copies
> > > of lots of .el files' .eln files in the same place.
> 
> > > This isn't a problem with .elc files.  Byte compiling a .el file simply
> > > overwrites the old .elc file with the new one.  But with .eln files, a
> > > random sequence of hex digits is appended to the name, preventing the
> > > new file overwriting the old one.
> 
> > > I don't know what portion of these .eln files are still needed, but I
> > > suspect it's only round about a half.
> 
> > > What's the best way to identify and delete these stale files?  A way of
> > > deleting them whilst doing native compilation would also be welcome.
> 
> > Did you try using the command native-compile-prune-cache?
> 
> No, I wasn't aware of the command.  It's not in the Emacs manual.

Not every comm and is (or should be) in the manual.

> Also, its doc string is too vague about which files it will (irrevocably)
> delete to make its use advisable without first reading and understanding
> its source code.

Excuse me?

  Remove .eln files that aren’t applicable to the current Emacs invocation.

What's vague about that?  Every .eln in the cache that cannot be used
by the current Emacs session will be deleted.

It's possible that your problem is something else, but your
description of what is your problem was so vague that it was
impossible for me to understand any better.