GNU bug report logs - #44701
28.0.50; [feature/native-comp] Use file-truename when building eln path hash

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Tad <tadfisher <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Cc: akrl <at> sdf.org
Subject: 28.0.50; [feature/native-comp] Use file-truename when building eln
 path hash
Date: Mon, 16 Nov 2020 20:03:15 -0800

It appears that `comp-el-to-eln-filename` uses `expand-file-name` to
determine the absolute filename to
hash. When the filename is a symlink, this results in a cache miss
depending on which path is loaded.

`file-truename' would be the equivalent to `(expand-file-name name
nil)`, except that it would resolve to a
single canonical path (in the absence of hardlinks, which is pathological).

If I may ask, what is the purpose behind the path component of the
hash? I would think a content hash
would suffice to disambiguate files in the .el<->.eln bijection.

Thanks,
Tad

Message #8 received at 44701 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Tad <tadfisher <at> gmail.com>
Cc: 44701 <at> debbugs.gnu.org
Subject: Re: 28.0.50; [feature/native-comp] Use file-truename when building
 eln path hash
Date: Wed, 18 Nov 2020 08:28:20 +0000

Hi Tad,

Tad <tadfisher <at> gmail.com> writes:

> It appears that `comp-el-to-eln-filename` uses `expand-file-name` to
> determine the absolute filename to
> hash. When the filename is a symlink, this results in a cache miss
> depending on which path is loaded.
>
> `file-truename' would be the equivalent to `(expand-file-name name
> nil)`, except that it would resolve to a
> single canonical path (in the absence of hardlinks, which is pathological).

It might be not 100% trivial as just calling `file-truename' from
`comp-el-to-eln-filename' in place of `expand-file-name'.  ATM I'm not
sure is good to call Lisp from there.  I'll give it a go.

> If I may ask, what is the purpose behind the path component of the
> hash? I would think a content hash
> would suffice to disambiguate files in the .el<->.eln bijection.

Sure we mainly use it to keep the eln-cache directory clean when
recompiling.

Thanks for reporting.

  Andrea

Message #11 received at 44701 <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Tad <tadfisher <at> gmail.com>
Cc: 44701 <at> debbugs.gnu.org
Subject: Re: bug#44701: 28.0.50; [feature/native-comp] Use file-truename
 when building eln path hash
Date: Wed, 18 Nov 2020 17:54:19 +0000

Hi Tad,

could you verify 3ae309bd59 fix the issue for you?

Thanks!

  Andrea

Message #14 received at 44701 <at> debbugs.gnu.org (full text, mbox):

From: Tad <tadfisher <at> gmail.com>
To: Andrea Corallo <akrl <at> sdf.org>
Cc: 44701 <at> debbugs.gnu.org
Subject: Re: bug#44701: 28.0.50; [feature/native-comp] Use file-truename when
 building eln path hash
Date: Wed, 18 Nov 2020 12:52:13 -0800

On Wed, Nov 18, 2020 at 9:54 AM Andrea Corallo <akrl <at> sdf.org> wrote:
>
> Hi Tad,
>
> could you verify 3ae309bd59 fix the issue for you?

Yes, this is working now. Here's a transcript:

    (comp-el-to-eln-filename
"/nix/store/...-emacs-ace-window-20200606.1259/share/emacs/site-lisp/elpa/ace-window-20200606.1259/ace-window.el")
    "/home/tad/.emacs.d/eln-cache/28.0.50-x86_64-pc-linux-gnu-6462edf10bdf79d2b67bce57511338e8/ace-window-d01e56e26487b663b5932fdce1c8c623-99728e8187c8762dea4b86e75d14412a.eln"

    (comp-el-to-eln-filename
"/nix/store/...-emacs-packages-deps/share/emacs/site-lisp/elpa/ace-window-20200606.1259/ace-window.el")
    "/home/tad/.emacs.d/eln-cache/28.0.50-x86_64-pc-linux-gnu-6462edf10bdf79d2b67bce57511338e8/ace-window-d01e56e26487b663b5932fdce1c8c623-99728e8187c8762dea4b86e75d14412a.eln"

This makes it possible to load AOT-compiled .eln files from the Nix
store, so thank you for implementing this change.

>
> Thanks!
>
>   Andrea

Message #19 received at 44701-done <at> debbugs.gnu.org (full text, mbox):

From: Andrea Corallo <akrl <at> sdf.org>
To: Tad <tadfisher <at> gmail.com>
Cc: 44701-done <at> debbugs.gnu.org
Subject: Re: bug#44701: 28.0.50; [feature/native-comp] Use file-truename
 when building eln path hash
Date: Wed, 18 Nov 2020 20:57:55 +0000

Tad <tadfisher <at> gmail.com> writes:

> This makes it possible to load AOT-compiled .eln files from the Nix
> store, so thank you for implementing this change.

That's good to hear!  Thank you for reporting, closing.

  Andrea

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