Modules were resolved with conflicting cross-version suffixes in ProjectRef about scala3-migrate HOT 4 CLOSED

Hello @nkcoder

This error means that some dependencies are declared twice, directly or transitively, on 2 different Scala versions. This is not valid, so you need to fix this problem before continuing the migration.

Here for instance, specs2-cats_2.13 depends on cats-effect_2.13 but cats-effect_3 is also declared. It would be better to use specs2-cats_3 by declaring:

"orgs.specs2" %% "specs2-cats" % "1.0.0-ALPHA-01"

instead of

"orgs.specs2" %% "specs2-cats" % "1.0.0-ALPHA-01" cross CrossVersion.fro3Use2.13

Unfortunately circe-generic-extra is not available for Scala 3, so you should maybe try to remove that dependency.

from scala3-migrate.

In general it is better not to use CrossVersion.for3Use2_13

from scala3-migrate.

Hi @adpi2, CrossVersion.for3Use2_13 is the output/suggestion of migrate-libs project_id, why shouldn't use it?

from scala3-migrate.

The tool should recommend it only if there is no Scala 3 compatible versions. It is a last resort and it does not give any guarantee that it will work.

In your case circe-generic-extras and specs2-mock are not published for Scala 3, so the tool suggests to use CrossVersion.for3Use2_13. Unfortunately it cannot work because they depend respectively on circe-core and specs2-core which are published for Scala 3. This problem is briefly explained here:

This is permitted as long as all libraries are resolved to a single binary version: you can have lib-foo_3 and lib-bar_2.13 in the same classpath, but you cannot have lib-foo_3 and lib-foo_2.13.

from scala3-migrate.