Old tag is selected when two tags reference same commit

[olafurpg]

We were just releasing scalameta v2.0.0 (🎉 ) and the v2.0.0 tag points to the same commit as the v2.0.0-RC3 tag, which we released a few days ago. sbt-dynver selected the version v2.0.0-RC3 when we pushed the v2.0.0 tag, see https://travis-ci.org/scalameta/scalameta/jobs/274261204#L671, causing publish to fail.

Tag v2.0.0
...
[info] Welcome to scalameta 2.0.0-RC3

I expected the version number to be 2.0.0.

[dwijnand]

Interesting - I thought I'd checked this case, but clearly not, sorry.

You at Scala World, Olaf? Could see to fix it then (me/you/together).

[olafurpg]

Yes, I'll be there! Sounds like a good bugfix for the SC Spree 😄

[samudurand]

Is there any progress on that issue ? Ideally we would like to have this fantastic plugin to choose the most recent tag. Or just the most recent version (v0.0.6 instead of v0.0.5 for instance) by simple string comparison maybe ?

[dwijnand]

I've not had a chance to look at this. Contributions welcome if they catch your fancy.

[samudurand]

Might, do, any hint on where to look for the change to make @dwijnand @olafurpg ? I currently don't have the time for digging into the whole code without any starting point. Otherwhise it will have to wait

[dwijnand]

Everything comes from one invocation of git describe: https://github.com/dwijnand/sbt-dynver/blob/v2.0.0/src/main/scala/sbtdynver/DynVerPlugin.scala#L121

Ideally there would be a flag for that that deals with this edge-case.

For testing (e.g to TDD your way to a solution) you could look to create a test similar to https://github.com/dwijnand/sbt-dynver/blob/v2.0.0/src/test/scala/sbtdynver/GH007.scala.

[dwijnand]

Hey @olafurpg,

I tried to reproduce this, but couldn't:

$ git init
Initialized empty Git repository in /s/t-git-multi-tag/.git/
$ echo 1 > f.txt
$ git add f.txt
$ git commit -m1
[master (root-commit) 6eda7fa] 1
 1 file changed, 1 insertion(+)
 create mode 100644 f.txt

$ git tag -a -s v2.0.0-RC3 -m 'Version 2.0.0-RC3'
$ git describe --tags --abbrev=8 --match v[0-9]* --always --dirty=+20180104-1200
v2.0.0-RC3

$ git tag -a -s v2.0.0 -m 'Version 2.0.0'
$ git describe --tags --abbrev=8 --match v[0-9]* --always --dirty=+20180104-1200
v2.0.0

Then I found this in the "SEARCH STRATEGY" section of git describe:

Annotated tags will always be preferred over lightweight tags, and tags with newer dates will always be preferred over tags with older dates.

(https://www.kernel.org/pub/software/scm/git/docs/git-describe.html#_search_strategy)

Initially I thought that the problem was that my reproduction wasn't faithfully reproducing the tag dates.

Instead it looks like the issue is that the v2.0.0 tag of Scalameta is a lightweight tag, while v2.0.0-RC3 is a proper annotated tag:

$ git show v2.0.0-RC3
tag v2.0.0-RC3
Tagger: Ólafur Páll Geirsson <olafurpg@gmail.com>
Date:   Wed Sep 6 11:49:04 2017 +0200

See #1109

commit 15a0187501dc8e5a6fe06d0e002ce1d3340968dc (tag: v2.0.0-RC3)
Merge: de1f4f2d5 10a2c60b0
Author: Ólafur Páll Geirsson <olafurpg@gmail.com>
Date:   Wed Sep 6 11:46:47 2017 +0200

    Merge pull request #1113 from olafurpg/ci-publish

    Fix CI publish infrastructure

$ git show v2.0.0
commit fa0dc78783b5cb26b17ee32eec5536d36915c82e (tag: v2.0.0)
Merge: 15a018750 c89ad57d7
Author: Ólafur Páll Geirsson <olafurpg@gmail.com>
Date:   Mon Sep 11 19:53:06 2017 +0200

    Merge pull request #1118 from olafurpg/master

    Redirect changelog files to GitHub releases.

I assume the tag was created with the GitHub Releases UI.

By default git describe never considers lightweight tags, we actually opt-ed into lightweight tags specifically for GitHub's Releases UI (see #14) by adding the --tags flag. Generally (IMHO) the difference isn't known by git users.

Unfortunately it doesn't look like there is a flag to make git describe ignore the annotated vs lightweight tag difference and only consider the dates. And even then I'm not 100% sure if that would be a good idea.

Running out of ideas I'm going to close this, but please comment if you have any ideas or thoughts.

[olafurpg]

Interesting. Thanks for digging into this @dwijnand I did indeed publish v2.0.0 from the GitHub release UI and iirc I tagged v2.0.0-RC3 locally. I didn't know about lightweight vs. annotated tags.

Totally fine to close this issue then 👍