Project export fails with java.nio.file.FileAlreadyExistsException with file and lib import

[carlosedp]

Version(s)

Scala CLI version: 1.0.0-RC1
Scala version (default): 3.2.2

Describe the bug

In a project which one file with main method imports another file which imports a lib, exporting to a mill or sbt project fails:

❯ scli export --mill --project testrepro -o testrepro .
The 'export' sub-command is experimental.
Please bear in mind that non-ideal user experience should be expected.
If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at https://github.com/VirtusLab/scala-cli
Exporting to a mill project...
Error: java.nio.file.FileAlreadyExistsException: /Users/cdepaula/repos/scala-playground/zio/test/testrepro/testrepro/src/Helpers.scala
For more details, please see '/Users/cdepaula/repos/scala-playground/zio/test/.scala-build/stacktraces/1680786544-2919053400650754756.log'

The project is:

❯ tree
[ 564]  ./
├── [ 180]  Helpers.scala
└── [ 160]  sample1.scala

  340 used in 1 directory, 2 files

❯ cat *
────────────────────────────────────────────────────────────────────────────────────────────────────
File: Helpers.scala
Size: 180 B
────────────────────────────────────────────────────────────────────────────────────────────────────
//> using scala "3.3.0-RC3"
//> using option "-source:future"
//> using lib "dev.zio::zio:2.0.10"

package testrepro

import zio.*

def printMy(msg: String): Unit =
  println(msg)
────────────────────────────────────────────────────────────────────────────────────────────────────
────────────────────────────────────────────────────────────────────────────────────────────────────
File: sample1.scala
Size: 160 B
────────────────────────────────────────────────────────────────────────────────────────────────────
//> using scala "3.3.0-RC3"

//> using file "Helpers.scala"
//> using option "-source:future"

package testrepro

@main
def main() =
  printMy("Hello, world!")
────────────────────────────────────────────────────────────────────────────────────────────────────

If I comment (remove) the using lib and import from Helpers.scala, it exports successfully or if I remove the sample 1 file, it also exports successfully.

Expected behaviour
Be able to export rojects that use both libs and local files.

The stacktrace mentioned shows:

❯ cat /Users/cdepaula/repos/scala-playground/zio/test/.scala-build/stacktraces/1680786544-2919053400650754756.log
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
File: /Users/cdepaula/repos/scala-playground/zio/test/.scala-build/stacktraces/1680786544-2919053400650754756.log
Size: 1.6 KB
────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
java.nio.file.FileAlreadyExistsException: /Users/cdepaula/repos/scala-playground/zio/test/testrepro/testrepro/src/Helpers.scala
  java.base@17.0.5/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:218)
  java.base@17.0.5/java.nio.file.Files.newByteChannel(Files.java:380)
  os.write$.write(ReadWriteOps.scala:64)
  os.write$.apply(ReadWriteOps.scala:77)
  scala.cli.exportCmd.MillProject.writeTo$$anonfun$5(MillProject.scala:143)
  scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
  scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
  scala.collection.IterableOnceOps.foreach(IterableOnce.scala:575)
  scala.collection.IterableOnceOps.foreach$(IterableOnce.scala:573)
  scala.collection.AbstractIterable.foreach(Iterable.scala:933)
  scala.collection.IterableOps$WithFilter.foreach(Iterable.scala:903)
  scala.cli.exportCmd.MillProject.writeTo(MillProject.scala:144)
  scala.cli.commands.export0.Export$.runCommand(Export.scala:195)
  scala.cli.commands.export0.Export$.runCommand(Export.scala:104)
  scala.cli.commands.ScalaCommand.run(ScalaCommand.scala:365)
  scala.cli.commands.ScalaCommand.run(ScalaCommand.scala:352)
  caseapp.core.app.CaseApp.main(CaseApp.scala:150)
  scala.cli.commands.ScalaCommand.main(ScalaCommand.scala:337)
  caseapp.core.app.CommandsEntryPoint.main(CommandsEntryPoint.scala:120)
  scala.cli.ScalaCliCommands.main(ScalaCliCommands.scala:124)
  scala.cli.ScalaCli$.main0(ScalaCli.scala:203)
  scala.cli.ScalaCli$.main(ScalaCli.scala:107)
  scala.cli.ScalaCli.main(ScalaCli.scala)

[Gedochao]

I believe the reason behind the error is that the Helpers.scala file in the example is in fact passed twice: once through the using file directive and once from the command line with ..
So a quick workaround would be to just export it like this:

scala-cli export --mill --project testrepro -o testrepro sample1.scala

Now, while passing sources twice like this isn't advisable, it still shouldn't break, so I added a fix in #2098

[carlosedp]

Thanks for the fix Piotr!