Version strings for VCS snapshots

[ludo@gnu.org (Ludovic Courtès)]

Eric Bavier <ericbavier@openmailbox.org> skribis:

> I realize we have no guidelines in the manual concerning the version
> field for git checkouts, but I wonder whether we should, as it comes up
> a bit.  Several existing packages use (string-append "1.2.3." commit),
> where "1.2.3" is the version of the corresponding source.  One other
> package uses the (string-append "1.2.3-c" commit) method, and another
> uses (string-append "1.2.3-" commit.  I personally prefer the "-"
> notation, since it distinguishes the commit hash from the version
> number (does it confuse any internal logic that assumes a package
> version number is the last component of the store path following a
> dash?).  In this case, the "-c" seems confusing because the commit hash
> itself begins with a 'c'.
>
> I recall some discussion previously about how it would be nice for
> git-checkout package versions to still "sort" nicely.

I think the goal should be to ensure lexicographic ordering, such that
‘guix package --upgrade’ DTRT.

In practice, that means the (string-append "1.2.3." commit) should be
avoided.

Instead we should use (string-append "1.2.3." REV "." commit) where REV
would be an integer we manually increment every time we upgrade to a
newer snapshot.

I don’t think adding “-” or “-c” before the commit is useful, but I
don’t have a strong opinion.

WDYT?

Ludo’.