Subject: Re: bug#44631: 28.0.50; Byte compilation fails if destination file is a mount point

From: Philipp Stephani <[email-masked]>
Date: Sun, 13 Dec 2020 17:41:55 +0100

Am So., 13. Dez. 2020 um 13:32 Uhr schrieb Lars Ingebrigtsen <[email-masked]>:
>
> Philipp Stephani <[email-masked]> writes:
>
> > I guess it also depends on what the semantics are that
> > byte-compile-file guarantees. If it attempts to guarantee atomicity,
> > then only a intra-filesystem rename (or similar alternatives such as
> > O_TMPFILE + linkat) are acceptable, and technically, not even the
> > current fallback on EXDEV (which makes rename-file nonatomic) is OK.
> > If atomic writes are best-effort, then we could always fall back to
> > copy-file + delete-file on any file-error.
>
> It's definitely best-effort, so altering byte-compile-file to try
> copy-file + delete-file sounds like the best solution to me.

I've now pushed a slightly different fix to master (commit
fe50a8b9ba79b4ac14a3a352d8bf84eaee4f2122).