Avoid race condition in parallel native-compilation

* lisp/emacs-lisp/comp.el (comp-delete-or-replace-file): Avoid
race condition by relying on 'rename-file' being an atomic
operation on Posix filesystems.  (Bug#68083)

(cherry picked from commit 6e2e34a5caa75a3430a1fb0d89900f9911c50436)

diff --git a/lisp/emacs-lisp/comp.el b/lisp/emacs-lisp/comp.el
index 3b2fd25e61c04f1adccb2683fd94010ec500a0af..f9eeef1b9e8310c64018bc4034cd865b5dada609 100644 (file)
--- a/lisp/emacs-lisp/comp.el
+++ b/lisp/emacs-lisp/comp.el
@@ -3339,9 +3339,9 @@ session."
         ;; 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.