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bug#35387: unpack phase in the gnu-build-system is sometimes non-determi
From: |
Ludovic Courtès |
Subject: |
bug#35387: unpack phase in the gnu-build-system is sometimes non-deterministic |
Date: |
Tue, 23 Apr 2019 16:36:40 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) |
Hi Chris,
Christopher Baines <address@hidden> skribis:
> I believe that the direnv package has encountered an issue with the
> gnu-build-system [1].
>
> 1: https://issues.guix.info/issue/35386
>
> Due to the combination of the 'setup-go-environment phase from the
> go-build-system, and the 'unpack phase of the gnu-build-system, there
> are two directories to be considered by first-subdirectory when called
> from the unpack phase.
>
> It seems from direnv that this either consistently, with the package
> working on one machine, or failing consistently on another.
>
> To avoid issues like this in the future, I think it would be good to
> have first-subdirectory raise an error if it's behaviour could be
> non-deterministic.
‘file-system-fold’ is just a wrapper around ‘readdir’ so the order in
which it sees directory entries is non-deterministic.
What about writing it like this:
(define (first-subdirectory directory)
"Return the file name of the first sub-directory of DIRECTORY."
(match (scandir directory
(lambda (file)
(and (not (member file '("." "..")))
(file-is-directory? (string-append directory "/"
file)))))
((first . _) first)))
The result will be deterministic since ‘scandir’ sorts entries.
Thanks,
Ludo’.