Error "Cyclic reference involving module" when using export on top level

[bjornregnell]

Minimized code

In file test.scala:

package p
export X._

object X:
  val A = 42

Output

[info] compiling 1 Scala source to /home/bjornr/tmp/bug-repl/target/scala-3.0.0-M3/classes ...
[error] -- [E046] Cyclic Error: /home/bjornr/tmp/bug-repl/src/main/scala/p/test.scala:2:7 
[error] 2 |export X.A
[error]   |       ^
[error]   |       Cyclic reference involving module X
[error] one error found
[error] one error found
[error] (Compile / compileIncremental) Compilation failed

Expectation

Export on top level should work.

There is a work-around: put the export in another file test2.scala and now both test.scala and test2.scala compiles:

package p

export X._

object Y {
  val B = A
}

Note that A is now visible on top level without an import X._ in file test2.scala , as expected.

Output with both files (but it shouldn't be necessary to put the export in another file...):

sbt:bug-repl> clean
[success] Total time: 0 s, completed Jan 17, 2021, 8:29:56 PM
sbt:bug-repl> console
[info] compiling 2 Scala sources to /home/bjornr/tmp/bug-repl/target/scala-3.0.0-M3/classes ...

scala> p.A                                                                      
val res0: Int = 42

[bjornregnell]

I have some problems with reproducing the work-around. Sometimes it works and sometimes not. It works more often after sbt clean but not always.