Compiler warnings with -Xsource:3.0 flag enabled

[ghost]

I'm trying to compile with both the -Werror and -Xsource:3.0 compiler flags in preparation for Scala 3. However, the generated code gives warnings, which -Werror treats as errors. An example,

[warn] .../target/scala-2.13/src_managed/.../Color.scala: Auto-application to `()` is deprecated. Supply the empty argument list `()` explicitly to invoke method unary_!,
[warn] or remove the empty argument list from its definition (Java-defined methods are exempt)
[warn] In Scala 3, an unapplied method like this will be eta-expanded into a function.
[warn]   lazy val values = scala.collection.immutable.Seq(RED, GREEN, BLUE)

For the protobuf enum,

enum Color {
    RED = 0;
    GREEN = 1;
    BLUE = 2;
}

Versions,

addSbtPlugin("com.thesamet" % "sbt-protoc" % "0.99.27")
libraryDependencies += "com.thesamet.scalapb" %% "compilerplugin" % "0.10.0-M6"

[thesamet]

I've tried enabling Xsource:3.0 and work through the warnings. I might be wrong, but my impression is that many of the warnings are spurious. I filed scala/bug#11889 and scala/bug#11890.

Given that the bugs reported are pretty obvious and Xsource:3.0 is rarely referenced online, I am suspecting this is not the best way to ensure source compatibility. Probably better just to try and compile with Scala 3.

BTW, what's the context of this Scala 3 preparation? Generally, you can always generate ScalaPB source code in a sub-project, compile in Scala 2 and depend on it from a Scala 3 project.

[thesamet]

Based on https://gitter.im/lampepfl/dotty?at=5e510c533ca8a67fb80f4c82 I am closing this issue, as Xsource:3.0 doesn't provide adequate indication for Scala 3.0 compatibility. Happy to continue the discussion on how to achieve what you are trying to accomplish.

[ghost]

Based on https://gitter.im/lampepfl/dotty?at=5e510c533ca8a67fb80f4c82 I am closing this issue, as Xsource:3.0 doesn't provide adequate indication for Scala 3.0 compatibility. Happy to continue the discussion on how to achieve what you are trying to accomplish.

Sounds reasonable, thanks for looking into this!