bug#68083: 30.0.50; Intermittent build failure with native compilation

[Aaron Jensen <aaronjensen@gmail.com>]

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Here's a patch, if helpful. I've tested it and can build with it.


Aaron


On Sat, Dec 30, 2023 at 3:54 PM, Aaron Jensen <aaronjensen@gmail.com> wrote:

> Works for me, though is it still an outstanding question as to whether or
> not we should add macro expand back?
>
> Also yeah if we add the t we can do what you suggested where it’s either a
> delete or rename force.
>
>
> Aaron
>
> On Sat, Dec 30 2023 at 1:46 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>
> From: Aaron Jensen <aaronjensen@gmail.com>
> Date: Sat, 30 Dec 2023 13:06:55 -0500
> Cc: acorallo@gnu.org, 68083@debbugs.gnu.org, jschmidt4gnu@vodafonemail.de
>
> On Sat, Dec 30, 2023 at 12:43 PM Eli Zaretskii <eliz@gnu.org> wrote:
> >
> > What happens if, instead of wrapping rename-file in condition-case,
> > you change that to say
> >
> > (t (if newfile
> > (rename-file newfile oldfile)
> > (delete-file oldfile))
>
> I don't really understand this change. The previous version of the code
> wraps the rename in a (when newfile) and deletes the oldfile right before
> that. The deletion would always be necessary if the oldfile exists unless
> OK-IF-ALREADY-EXISTS is specified in rename-file.
>
> Sorry, I meant to add the OK-IF-ALREADY-EXISTS argument non-nil, of
> course.
>
> The point is that you can rename a file if the OLDFILE exists with no
> problem, and that is supposed to be an atomic operation, so no race
> conditions.
>
> Indeed, but we aren't specifying OK-IF-ALREADY-EXISTS, so if another
> process does the same compile at the same time (and therefore the same
> rename), they will conflict. We could specify OK-IF-ALREADY-EXISTS instead
> and that works as well:
>
> Then I prefer this version.
>
>

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From c1ab27179e68b94c9adb4905c677c7f344c09e6d Mon Sep 17 00:00:00 2001
From: Aaron Jensen <aaronjensen@gmail.com>
Date: Sat, 30 Dec 2023 18:06:45 -0500
Subject: [PATCH] * comp.el (comp-delete-or-replace-file): Fix parallel
 compilation

---
 lisp/emacs-lisp/comp.el | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lisp/emacs-lisp/comp.el b/lisp/emacs-lisp/comp.el
index 3b2fd25e61c..f9eeef1b9e8 100644
--- a/lisp/emacs-lisp/comp.el
+++ b/lisp/emacs-lisp/comp.el
@@ -3339,9 +3339,9 @@ comp-delete-or-replace-file
         ;; Remove the old eln instead of copying the new one into it
         ;; to get a new inode and prevent crashes in case the old one
         ;; is currently loaded.
-        (t (delete-file oldfile)
-           (when newfile
-             (rename-file newfile oldfile)))))
+        (t (if newfile
+               (rename-file newfile oldfile t)
+             (delete-file oldfile)))))
 
 (defun comp--native-compile (function-or-file &optional with-late-load output)
   "Compile FUNCTION-OR-FILE into native code.
-- 
2.42.1