Paket downgrades direct dependency without reason

[auxym]

Description

Paket resolves a direct dependency to a lower version than available, even though the latest version is also a valid resolution, with the same transitive dependency solution.

I would really like to give a reproduction sample here, but unfortunately, I only had this bug happen using our internal artifact server and packages. Instead, please try to follow my reasoning through this log, which is the result of running paket update -v on a paket.dependencies file with a single (nuget) entry : delphi-tf-latest-convert: https://gist.github.com/auxym/5b87b8cd92ab80b75a68addf65492e68

Here is what I understand is happening:

1. L43: The latest available version of delphi-tf-latest-convert is found from the feed: 0.0.75. This is the desired version.

2. L91. We resolved an additional transitive dependency : Taxdoc, to the latest available. So far so good.

3. L153 This is where things get weird. Since L91, paket found a conflict in the dependencies of taxdoc and latest-calc. To fix this, it decided to downgrade our direct dependency, delphi-tf-latest-convert, to 0.0.74. This is even though the transitive dependencies of 0.0.74 and 0.0.75 are absolutely identical.

4. L332 Final resolution solution: we have delphi-tf-latest-convert v 0.0.74, even though the latest version (0.0.75), would be valid with the exact same resolution.

Repro steps

See above, unfortunately I cannot provide a repro example using external projects.

Expected behavior

Given a valid solution to version resolution, I would expect our direct dependencies to be resolved to the highest possible version.

Actual behavior

Paket seems to always resolve to exactly one version behind.

Known workarounds

Right now, taxdoc is resolved first (see step 2 above). I understand that this is because of alphabetical order, as none of the transitive dependencies have any version constraint on them (from what I understand of Paket Resolution Algorithm).

We are working around the issue by adding a very loose version constraint to tf-latest-calc, which forces paket to attempt resolving it first, before TaxDoc. This results in correctly resolving delphi-tf-latest-convert to the latest version (0.0.75).

[forki]

I openend #3104 with a start for a unittest that nails down your case. Please take a look and extent the graph until it breaks like you see in the real world case

[auxym]

Thanks, I'll try setting up something that reproduces the issue.

[auxym]

OK, I created #3106 which is based on #3104 and reproduces the exact same issue we get.

For additional fun, try adding additional versions of delphi-tf-latest-convert to the graph. Paket always resolves one version prior to latest :)

[forki]

Thank you. I will take a look Am 09.03.2018 15:44 schrieb "Francis Thérien" <[email protected]>:

…

OK, I created #3106 <#3106> which is based on #3104 <#3104> and reproduces the exact same issue we get. For additional fun, try adding additional versions of delphi-tf-latest-convert to the graph. Paket always resolves one version prior to latest :) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#3103 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADgNIpylAV0-jYOi7QmM7JeXV01UEfaks5tcpVVgaJpZM4SjBdt> .

[forki]

it's confirmed as bug

[forki]

@auxym I'm working on a fix in #3104 but it's not trivial. Interesting corner case.