Wrote an early version of dottyijar

Currently, it just strips private `val`s and `def`s and definition
values, but I plan on making it more aggresive in the future.

Author: Jaden Peterson

scala/private/macros/scala_repositories.bzl

@@ -189,6 +189,7 @@ def _artifact_ids(scala_version):
             "io_bazel_rules_scala_scala_library_2",
             "io_bazel_rules_scala_scala_reflect_2",
             "io_bazel_rules_scala_scala_tasty_core",
+            "io_bazel_rules_scala_scala_tasty_inspector",
             "org_jline_jline_native",
             "org_jline_jline_reader",
             "org_jline_jline_terminal",

scripts/create_repository.py

@@ -137,6 +137,7 @@ def select_root_artifacts(scala_version, scala_major, is_scala_3) -> List[str]:
             f'org.scala-lang:scala3-compiler_3:{scala_version}',
             f'org.scala-lang:scala3-library_3:{scala_version}',
             f'org.scala-lang:scala3-interfaces:{scala_version}',
+            f'org.scala-lang:scala3-tasty-inspector_3:{scala_version}',
             f'org.scala-lang:tasty-core_3:{scala_version}',
             f'org.scala-sbt:compiler-interface:{SBT_COMPILER_INTERFACE_VERSION}',
             f'org.scala-sbt:util-interface:{SBT_UTIL_INTERFACE_VERSION}',

src/scala/io/bazel/rules_scala/dottyijar/BUILD

@@ -0,0 +1,42 @@
+load("//scala:scala.bzl", "scala_library_for_plugin_bootstrapping", "scala_specs2_junit_test")
+load("@rules_java//java:defs.bzl", "java_binary")
+
+scala_library_for_plugin_bootstrapping(
+    name = "dottyijar-library",
+    srcs = glob(
+        ["*.scala"],
+        exclude = ["*.spec.scala"],
+    ),
+    scala_version = "3.6.2",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//src/scala/io/bazel/rules_scala/dottyijar/tasty",
+        "//src/scala/io/bazel/rules_scala/dottyijar/tasty/format",
+        "@com_softwaremill_common_tagging_3_6_2",
+        "@dev_zio_izumi_reflect_3_6_2",
+    ],
+)
+
+# TODO: Eventually, we should make a bootstrapping toolchain so we don't have to create a `*_for_plugin_bootstrapping` equivalent for each Scala rule.
+java_binary(
+    name = "dottyijar",
+    main_class = "io.bazel.rules_scala.dottyijar.DottyIjar",
+    visibility = ["//visibility:public"],
+    runtime_deps = [":dottyijar-library"],
+)
+
+scala_specs2_junit_test(
+    name = "specs",
+    srcs = glob(["*.spec.scala"]),
+    scala_version = "3.6.2",
+    suffixes = ["Spec"],
+    deps = [
+        ":dottyijar-library",
+        "//src/scala/io/bazel/rules_scala/dottyijar/tasty:test",
+        "@io_bazel_rules_scala_org_specs2_specs2_common_3_6_2",
+        "@io_bazel_rules_scala_org_specs2_specs2_core_3_6_2",
+        "@io_bazel_rules_scala_org_specs2_specs2_junit",
+        "@io_bazel_rules_scala_org_specs2_specs2_matcher_3_6_2",
+        "@io_bazel_rules_scala_scala_tasty_inspector_3_6_2",
+    ],
+)

src/scala/io/bazel/rules_scala/dottyijar/DottyIjar.scala

@@ -0,0 +1,119 @@
+package io.bazel.rules_scala.dottyijar
+
+import io.bazel.rules_scala.dottyijar.tasty.Tasty
+import io.bazel.rules_scala.dottyijar.tasty.format.{TastyFormat, TastyReader, TastyWriter}
+import java.io.FileOutputStream
+import java.nio.file.{Path, Paths}
+import java.nio.file.attribute.FileTime
+import java.util.zip.{ZipEntry, ZipFile, ZipOutputStream}
+import scala.jdk.CollectionConverters.*
+
+object DottyIjar {
+  private def writeInterfaceJar(inputJar: ZipFile, outputStream: ZipOutputStream): Unit = {
+    def copyEntryWithContent(entry: ZipEntry, content: Array[Byte]): Unit = {
+      val newEntry = new ZipEntry(entry.getName)
+
+      newEntry.setCreationTime(FileTime.fromMillis(0))
+      newEntry.setLastAccessTime(FileTime.fromMillis(0))
+      newEntry.setLastModifiedTime(FileTime.fromMillis(0))
+
+      outputStream.putNextEntry(newEntry)
+      outputStream.write(content, 0, content.length)
+    }
+
+    def copyEntry(entry: ZipEntry): Unit = copyEntryWithContent(entry, inputJar.getInputStream(entry).readAllBytes())
+
+    outputStream.setComment(inputJar.getComment)
+    outputStream.setLevel(0)
+
+    val entryNames = inputJar.entries.asScala.map(_.getName).toSet
+
+    inputJar.entries.asScala.foreach {
+      case entry if entry.getName.startsWith("META-INF/") => copyEntry(entry)
+      case entry if entry.getName.endsWith(".class") =>
+        val i = entry.getName.lastIndexOf('/')
+        val directory = entry.getName.slice(0, i)
+        val filename = entry.getName.slice(i + 1, entry.getName.length)
+        val j = filename.indexOf("$")
+        val tastyFileBaseName = if (j == -1) filename.stripSuffix(".class") else filename.slice(0, j)
+
+        if (!entryNames(s"$directory/$tastyFileBaseName.tasty")) {
+          copyEntry(entry)
+        }
+
+      case entry if entry.getName.endsWith(".tasty") =>
+        val content = inputJar.getInputStream(entry).readAllBytes()
+        val updatedContent = TastyUpdater.updateTastyFile(content)
+
+        copyEntryWithContent(entry, updatedContent)
+
+      case entry => copyEntry(entry)
+    }
+  }
+
+  def main(arguments: Array[String]): Unit = Arguments
+    .parseArguments(arguments)
+    .fold(
+      println,
+      arguments => {
+        val inputJar = new ZipFile(arguments.inputPath.toFile)
+
+        try {
+          val outputStream = new ZipOutputStream(new FileOutputStream(arguments.outputPath.toFile))
+
+          try {
+            writeInterfaceJar(inputJar, outputStream)
+          } finally {
+            outputStream.close()
+          }
+        } finally {
+          inputJar.close()
+        }
+      },
+    )
+}
+
+private case class Arguments(inputPath: Path, outputPath: Path)
+
+object Arguments {
+  def parseArguments(arguments: Array[String]): Either[String, Arguments] = arguments
+    .foldLeft[Either[String, UnvalidatedArguments]](Right(UnvalidatedArguments())) {
+      case (unvalidatedArguments, argument) =>
+        unvalidatedArguments.flatMap { unvalidatedArguments =>
+          argument match {
+            case "-h" | "--help" =>
+              Left(
+                """dottyijar removes information from Scala 3 JARs that aren't needed for compilation.
+                |
+                |Usage:
+                |  dottyijar <input> <output>
+                |  dottyijar -h | --help
+                |
+                |Options:
+                |  -h --help  Show this screen.""".stripMargin,
+              )
+
+            case _ =>
+              lazy val path = Paths.get(argument)
+
+              if (unvalidatedArguments.inputPath.isEmpty) {
+                Right(unvalidatedArguments.copy(inputPath = Some(path)))
+              } else if (unvalidatedArguments.outputPath.isEmpty) {
+                Right(unvalidatedArguments.copy(outputPath = Some(path)))
+              } else {
+                Left(s"Unexpected argument: $argument")
+              }
+          }
+        }
+    }
+    .flatMap(_.validate)
+}
+
+private case class UnvalidatedArguments(inputPath: Option[Path] = None, outputPath: Option[Path] = None) {
+  def validate: Either[String, Arguments] = (
+    for {
+      inputPath <- inputPath
+      outputPath <- outputPath
+    } yield Arguments(inputPath, outputPath)
+  ).toRight("Please provide paths to the input and output JARs.")
+}