Using +publish or +publishLocal leads to double publication and errors

[gaeljw]

Considering a project configured with 3 Scala versions as axis:

val scala211 = "2.11.12"
val scala212 = "2.12.15"
val scala213 = "2.13.7"

scalaVersion := scala212

lazy val core = (projectMatrix in file("xxx"))
  .jvmPlatform(scalaVersions = Seq(scala211, scala212, scala213))

If I run publishLocal I can see it publishes artifacts only once per Scala version:

[info]  published my-project-xxx_2.12 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.12/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/poms/my-project-xxx_2.12.pom
[info]  published my-project-xxx_2.12 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.12/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/jars/my-project-xxx_2.12.jar
...
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/poms/my-project-xxx_2.11.pom
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/jars/my-project-xxx_2.11.jar
...
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/poms/my-project-xxx_2.13.pom
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1157-SNAPSHOT/jars/my-project-xxx_2.13.jar

However, running +publishLocal, it publishes once for each Scala version and publishes all versions one time more (as part of the default Scala version build in my understanding, 2.12 in my case):

[info] Setting Scala version to 2.11.12 on 2 projects.
[info] Excluded 5 projects, run ++ 2.11.12 -v for more details.
...
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/poms/my-project-xxx_2.11.pom
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/jars/my-project-xxx_2.11.jar
...
[info] Setting Scala version to 2.12.15 on 3 projects.
[info] Excluded 4 projects, run ++ 2.12.15 -v for more details.
...
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/poms/my-project-xxx_2.11.pom
[info]  published my-project-xxx_2.11 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.11/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/jars/my-project-xxx_2.11.jar
...
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/poms/my-project-xxx_2.13.pom
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/jars/my-project-xxx_2.13.jar
...
[info]  published my-project-xxx_2.12 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.12/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/poms/my-project-xxx_2.12.pom
[info]  published my-project-xxx_2.12 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.12/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/jars/my-project-xxx_2.12.jar
...
[info] Setting Scala version to 2.13.7 on 2 projects.
[info] Excluded 5 projects, run ++ 2.13.7 -v for more details.
...
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/poms/my-project-xxx_2.13.pom
[info]  published my-project-xxx_2.13 to /home/my-user/.ivy2/local/com.groupid/my-project-xxx_2.13/0.0.0+469-310ddce6+20250226-1204-SNAPSHOT/jars/my-project-xxx_2.13.jar

Is that an expected behaviour? If so, I would suggest documenting it explicitly.

The issue with this behaviour is that for releases, you can end up with errors from the artifact repository because uploading an already published version is forbidden. Like [error] java.io.IOException: destination file exists and overwrite == false.

[gaeljw]

Sounds partially related to #75 and #20