[bug#38408] [PATCH v9 2/8] guix: import: crate: Use semver to resovle module versions

[Ludovic Courtès]

Efraim Flashner <address@hidden> skribis:

> On Mon, Feb 17, 2020 at 03:35:20PM +0100, Ludovic Courtès wrote:

[...]

>> --8<---------------cut here---------------start------------->8---
>> scheme@(guix import crate)> (crate-version-dependencies (car (crate-versions 
>> (lookup-crate "blake2-rfc"))))
>> $8 = (#<<crate-dependency> id: "arrayvec" kind: normal requirement: 
>> "^0.4.6"> #<<crate-dependency> id: "constant_time_eq" kind: normal 
>> requirement: "^0.1.0"> #<<crate-dependency> id: "data-encoding" kind: dev 
>> requirement: "^2.0.0"> #<<crate-dependency> id: "clippy" kind: normal 
>> requirement: "^0.0.41">)
>> --8<---------------cut here---------------end--------------->8---
>> 
>> In the example above, the importer could “just” fetch version 0.4.6 of
>> arrayvec, version 0.1.0 of constant_time_eq, etc., no?
>> 
>> It’s an approximation because the caret (^) means more than just this,
>> but hopefully it’s a good approximation.
>> 
>> Am I missing something?
>> 
>> Ludo’.
>
> Here we're looking at a minimum of 0.4.6 for arrayvec. According to
> here¹ we'd really want to import 0.4.12, which is the latest 0.4.x
> release.

That’s why I wrote that 0.4.6 is an approximation (probably a good one
because it’s apparently known to work.)

We can do something smarter, but then it’s only useful if the updater is
equally smart—that is, it can update 0.4.6 to 0.4.13 whenever that
version is out, knowing that blake2-rfc will still work fine.

Tricky!  WDYT?

Ludo’.