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scalapb-support-java-generation #5817

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4e8e912
scalapb-support-java-generation
Sep 6, 2025
12b13f9
[autofix.ci] apply automated fixes
autofix-ci[bot] Sep 6, 2025
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5 changes: 4 additions & 1 deletion contrib/scalapblib/src/mill/contrib/scalapblib/ScalaPBModule.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@ trait ScalaPBModule extends ScalaModule {

def scalaPBVersion: T[String]

def scalaPBGenerators: T[Seq[Generator]] = Seq[Generator](ScalaGen)
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Can we have some docs here which answers: What is a generator? Which can be choosen from? What is the default?


def scalaPBFlatPackage: T[Boolean] = Task { false }

def scalaPBJavaConversions: T[Boolean] = Task { false }
Expand Down Expand Up @@ -141,7 +143,8 @@ trait ScalaPBModule extends ScalaModule {
scalaPBSources().map(_.path),
scalaPBOptions(),
Task.dest,
scalaPBCompileOptions()
scalaPBCompileOptions(),
scalaPBGenerators()
)
}
}
33 changes: 25 additions & 8 deletions contrib/scalapblib/src/mill/contrib/scalapblib/ScalaPBWorker.scala
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Expand Up @@ -5,6 +5,7 @@ import java.io.File

import mill.api.PathRef
import mill.api.{Discover, ExternalModule}
import upickle.default.ReadWriter

class ScalaPBWorker {

Expand All @@ -15,16 +16,17 @@ class ScalaPBWorker {
sources: Seq[File],
scalaPBOptions: String,
generatedDirectory: File,
otherArgs: Seq[String]
otherArgs: Seq[String],
generators: Seq[Generator]
): Unit = {
val pbcClasspath = scalaPBClasspath.map(_.path).toVector
mill.util.Jvm.withClassLoader(pbcClasspath, null) { cl =>
val scalaPBCompilerClass = cl.loadClass("scalapb.ScalaPBC")
val mainMethod = scalaPBCompilerClass.getMethod("main", classOf[Array[java.lang.String]])
val opts = if (scalaPBOptions.isEmpty) "" else scalaPBOptions + ":"
val args = otherArgs ++ Seq(
s"--scala_out=${opts}${generatedDirectory.getCanonicalPath}"
) ++ roots.map(root => s"--proto_path=${root.getCanonicalPath}") ++ sources.map(
val args = otherArgs ++ generators.map { gen =>
val opts = if (scalaPBOptions.isEmpty || !gen.supportsScalaPBOptions) "" else scalaPBOptions + ":"
s"${gen.generator}=$opts${generatedDirectory.getCanonicalPath}"
} ++ roots.map(root => s"--proto_path=${root.getCanonicalPath}") ++ sources.map(
_.getCanonicalPath
)
ctx.log.debug(s"ScalaPBC args: ${args.mkString(" ")}")
Expand Down Expand Up @@ -70,7 +72,8 @@ class ScalaPBWorker {
scalaPBSources: Seq[os.Path],
scalaPBOptions: String,
dest: os.Path,
scalaPBCExtraArgs: Seq[String]
scalaPBCExtraArgs: Seq[String],
generators: Seq[Generator]
)(implicit ctx: mill.api.TaskCtx): mill.api.Result[PathRef] = {
val compiler = scalaPB(scalaPBClasspath)
val sources = scalaPBSources.flatMap {
Expand All @@ -86,7 +89,7 @@ class ScalaPBWorker {
Seq(ioFile)
}
val roots = scalaPBSources.map(_.toIO).filter(_.isDirectory)
compiler.compileScalaPB(roots, sources, scalaPBOptions, dest.toIO, scalaPBCExtraArgs)
compiler.compileScalaPB(roots, sources, scalaPBOptions, dest.toIO, scalaPBCExtraArgs, generators)
mill.api.Result.Success(PathRef(dest))
}
}
Expand All @@ -97,10 +100,24 @@ trait ScalaPBWorkerApi {
source: Seq[File],
scalaPBOptions: String,
generatedDirectory: File,
otherArgs: Seq[String]
otherArgs: Seq[String],
generators: Seq[Generator]
): Unit
}

sealed trait Generator derives ReadWriter {
def generator: String
def supportsScalaPBOptions: Boolean
}
case object ScalaGen extends Generator {
override def generator: String = "--scala_out"
override def supportsScalaPBOptions: Boolean = true
}
case object JavaGen extends Generator {
override def generator: String = "--java_out"
override def supportsScalaPBOptions: Boolean = false // Java options are specified directly in the proto file
}

object ScalaPBWorkerApi extends ExternalModule {
def scalaPBWorker: Worker[ScalaPBWorker] = Task.Worker { new ScalaPBWorker() }
lazy val millDiscover = Discover[this.type]
Expand Down
84 changes: 57 additions & 27 deletions contrib/scalapblib/test/src/mill/contrib/scalapblib/TutorialTests.scala
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Expand Up @@ -11,7 +11,9 @@ import utest.{TestSuite, Tests, assert, *}
object TutorialTests extends TestSuite {
val testScalaPbVersion = "0.11.7"

trait TutorialBase extends TestRootModule
trait TutorialBase extends TestRootModule {
val core: TutorialModule
}

trait TutorialModule extends ScalaPBModule {
def scalaVersion = sys.props.getOrElse("TEST_SCALA_2_12_VERSION", ???)
Expand Down Expand Up @@ -70,19 +72,68 @@ object TutorialTests extends TestSuite {
lazy val millDiscover = Discover[this.type]
}

object TutorialWithJavaGen extends TutorialBase {
object core extends TutorialModule {
override def scalaPBGenerators = Seq(JavaGen)
}

lazy val millDiscover = Discover[this.type]
}

object TutorialWithScalaAndJavaGen extends TutorialBase {
object core extends TutorialModule {
override def scalaPBGenerators = Seq[Generator](ScalaGen, JavaGen)
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Seems like we need to explicitly define the type of the Seq here, otherwise upickle can't find the implicit reader.
although having a single value in there seems to work fine...

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Does making Generator an enum fixes the issue?

}

lazy val millDiscover = Discover[this.type]
}

val resourcePath: os.Path = os.Path(sys.env("MILL_TEST_RESOURCE_DIR"))

def protobufOutPath(eval: UnitTester): os.Path =
eval.outPath / "core/compileScalaPB.dest/com/example/tutorial"

def compiledSourcefiles: Seq[os.RelPath] = Seq[os.RelPath](
def compiledScalaSourcefiles: Seq[os.RelPath] = Seq[os.RelPath](
os.rel / "AddressBook.scala",
os.rel / "Person.scala",
os.rel / "TutorialProto.scala",
os.rel / "Include.scala",
os.rel / "IncludeProto.scala"
)

def compiledJavaSourcefiles: Seq[os.RelPath] = Seq[os.RelPath](
os.rel / "AddressBookProtos.java",
os.rel / "IncludeOuterClass.java"
)

// Helper function to test compilation with different generators
def testCompilation(
module: TutorialBase,
expectedFiles: Seq[os.RelPath]
): Unit = {
UnitTester(module, resourcePath).scoped { eval =>
if (!mill.constants.Util.isWindows) {
val Right(result) = eval.apply(module.core.compileScalaPB): @unchecked

val outPath = protobufOutPath(eval)
val outputFiles = os.walk(result.value.path).filter(os.isFile)
val expectedSourcefiles = expectedFiles.map(outPath / _)

assert(
result.value.path == eval.outPath / "core/compileScalaPB.dest",
outputFiles.nonEmpty,
outputFiles.forall(expectedSourcefiles.contains),
outputFiles.size == outputFiles.size,
result.evalCount > 0
)

// don't recompile if nothing changed
val Right(result2) = eval.apply(module.core.compileScalaPB): @unchecked
assert(result2.evalCount == 0)
}
}
}

def tests: Tests = Tests {
test("scalapbVersion") {

Expand All @@ -97,30 +148,9 @@ object TutorialTests extends TestSuite {
}

test("compileScalaPB") {
test("calledDirectly") - UnitTester(Tutorial, resourcePath).scoped { eval =>
if (!mill.constants.Util.isWindows) {
val Right(result) = eval.apply(Tutorial.core.compileScalaPB): @unchecked

val outPath = protobufOutPath(eval)

val outputFiles = os.walk(result.value.path).filter(os.isFile)

val expectedSourcefiles = compiledSourcefiles.map(outPath / _)

assert(
result.value.path == eval.outPath / "core/compileScalaPB.dest",
outputFiles.nonEmpty,
outputFiles.forall(expectedSourcefiles.contains),
outputFiles.size == 5,
result.evalCount > 0
)

// don't recompile if nothing changed
val Right(result2) = eval.apply(Tutorial.core.compileScalaPB): @unchecked

assert(result2.evalCount == 0)
}
}
test("scalaGen") - testCompilation(Tutorial, compiledScalaSourcefiles)
test("javaGen") - testCompilation(TutorialWithJavaGen, compiledJavaSourcefiles)
test("scalaAndJavaGen") - testCompilation(TutorialWithScalaAndJavaGen, compiledScalaSourcefiles ++ compiledJavaSourcefiles)

test("calledWithSpecificFile") - UnitTester(
TutorialWithSpecificSources,
Expand Down Expand Up @@ -165,7 +195,7 @@ object TutorialTests extends TestSuite {
//
// // val outputFiles = os.walk(outPath).filter(_.isFile)
//
// // val expectedSourcefiles = compiledSourcefiles.map(outPath / _)
// // val expectedSourcefiles = compiledScalaSourcefiles.map(outPath / _)
//
// // assert(
// // outputFiles.nonEmpty,
Expand Down
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