coverageReport task fails when using Scala 3.2.0 with -Yexplicit-nulls

[klaeufer]

sbt-scoverage seems to be incompatible with Scala 3's explicit nulls language feature.

I first made some minimal changes to convert sbt-scoverage-samples to explicit nulls:

https://github.com/scoverage/sbt-scoverage-samples/compare/main...klaeufer:sbt-scoverage-samples:scala3-explicit-nulls?expand=1

When running sbt clean coverage test coverageReport, all tests still pass, but the subsequent coverageReport task fails. The cause seems to be the stdLibPatches made to Predef.scala to enable the explicit nulls feature.

[info] Waiting for measurement data to sync...
[info] Reading scoverage instrumentation [/Users/laufer/Dropbox/Home/Work/teaching/cs371/sbt-scoverage-samples/target/scala-3.2.0/scoverage-data/scoverage.coverage]
[info] Reading scoverage measurements...
[info] Generating scoverage reports...
[info] Written Cobertura report [/Users/laufer/Dropbox/Home/Work/teaching/cs371/sbt-scoverage-samples/target/scala-3.2.0/coverage-report/cobertura.xml]
[info] Written XML coverage report [/Users/laufer/Dropbox/Home/Work/teaching/cs371/sbt-scoverage-samples/target/scala-3.2.0/scoverage-report/scoverage.xml]
[error] java.lang.RuntimeException: No source root found for '/Users/laufer/Dropbox/Home/Work/teaching/cs371/sbt-scoverage-samples/library/src/scala/runtime/stdLibPatches/Predef.scala' (source roots: '/Users/laufer/Dropbox/Home/Work/teaching/cs371/sbt-scoverage-samples/src/main/scala/')
...

[ckipp01]

Thanks for the report @klaeufer although I'm a bit surprised by the issue. The coverer samples has some odd stuff going on, so it actually might be better to provide a hello world project with a very minimal reproduction just to confirm this happens on a fresh project using 3.2.x and these settings. Locally trying it out on a hello world project I didn't have that issue.

[klaeufer]

@ckipp01 Thanks and sorry it took me this long to respond. Here is the hello world project: https://github.com/klaeufer/hello-explicitnulls-scala I confirmed in GitPod that the same issue occurs.