Generate semantic DBs for Java sources too

Author: alexarchambault

build.sc

@@ -263,6 +263,10 @@ class Build(val crossScalaVersion: String)
          |  def semanticDbPluginModuleName = "semanticdb-scalac"
          |  def semanticDbPluginVersion = "${Deps.scalametaTrees.dep.version}"
          |
+         |  def semanticDbJavacPluginOrganization = "${Deps.semanticDbJavac.dep.module.organization.value}"
+         |  def semanticDbJavacPluginModuleName = "${Deps.semanticDbJavac.dep.module.name.value}"
+         |  def semanticDbJavacPluginVersion = "${Deps.semanticDbJavac.dep.version}"
+         |
          |  def localRepoResourcePath = "$localRepoResourcePath"
          |
          |  def jmhVersion = "1.29"

modules/build/src/main/scala/scala/build/Build.scala

@@ -559,8 +559,10 @@ object Build {
         s"-Xplugin:${path.toAbsolutePath}"
     }
 
+    val generateSemanticDbs = options.scalaOptions.generateSemanticDbs.getOrElse(false)
+
     val semanticDbScalacOptions =
-      if (options.scalaOptions.generateSemanticDbs.getOrElse(false))
+      if (generateSemanticDbs)
         if (params.scalaVersion.startsWith("2."))
           Seq(
             "-Yrangepos",
@@ -574,6 +576,29 @@ object Build {
           )
       else Nil
 
+    val semanticDbJavacOptions =
+      // FIXME Should this be in scalaOptions, now that we use it for javac stuff too?
+      if (generateSemanticDbs) {
+        // from https://github.com/scalameta/metals/blob/04405c0401121b372ea1971c361e05108fb36193/metals/src/main/scala/scala/meta/internal/metals/JavaInteractiveSemanticdb.scala#L137-L146
+        val compilerPackages = Seq(
+          "com.sun.tools.javac.api",
+          "com.sun.tools.javac.code",
+          "com.sun.tools.javac.model",
+          "com.sun.tools.javac.tree",
+          "com.sun.tools.javac.util"
+        )
+        val exports = compilerPackages.flatMap { pkg =>
+          Seq("-J--add-exports", s"-Jjdk.compiler/$pkg=ALL-UNNAMED")
+        }
+
+        Seq(
+          // does the path need to be escaped somehow?
+          s"-Xplugin:semanticdb -sourceroot:${inputs.workspace} -targetroot:javac-classes-directory"
+        ) ++ exports
+      }
+      else
+        Nil
+
     val sourceRootScalacOptions =
       if (params.scalaVersion.startsWith("2.")) Nil
       else Seq("-sourceroot", inputs.workspace.toString)
@@ -601,7 +626,7 @@ object Build {
       compilerClassPath = artifacts.compilerClassPath
     )
 
-    val javacOptions = javacReleaseV ++ options.javaOptions.javacOptions
+    val javacOptions = javacReleaseV ++ semanticDbJavacOptions ++ options.javaOptions.javacOptions
 
     // `test` scope should contains class path to main scope
     val mainClassesPath =

modules/build/src/main/scala/scala/build/options/BuildOptions.scala

@@ -114,8 +114,19 @@ final case class BuildOptions(
       scalaOptions.compilerPlugins
   }
 
+  private def semanticDbJavacPlugins: Either[BuildException, Seq[AnyDependency]] = either {
+    val generateSemDbs = scalaOptions.generateSemanticDbs.getOrElse(false)
+    if (generateSemDbs)
+      Seq(
+        dep"$semanticDbJavacPluginOrganization:$semanticDbJavacPluginModuleName:$semanticDbJavacPluginVersion"
+      )
+    else
+      Nil
+  }
+
   def javacPluginDependencies: Either[BuildException, Seq[Positioned[AnyDependency]]] = either {
-    javaOptions.javacPluginDependencies
+    value(semanticDbJavacPlugins).map(Positioned.none(_)) ++
+      javaOptions.javacPluginDependencies
   }
 
   def allExtraJars: Seq[Path] =

modules/integration/src/test/scala/scala/cli/integration/CompileTestDefinitions.scala

@@ -321,4 +321,34 @@ abstract class CompileTestDefinitions(val scalaVersionOpt: Option[String])
       )
     }
   }
+
+  test("Javac SemanticDB") {
+    val inputs = TestInputs(
+      Seq(
+        os.rel / "foo" / "Test.java" ->
+          """package foo;
+            |
+            |public class Test {
+            |  public static void main(String[] args) {
+            |    System.err.println("Hello");
+            |  }
+            |}
+            |""".stripMargin
+      )
+    )
+    inputs.fromRoot { root =>
+      os.proc(TestUtil.cli, "compile", extraOptions, "--semantic-db", ".")
+        .call(cwd = root)
+
+      val files = os.walk(root / ".scala")
+      val semDbFiles = files
+        .filter(_.last.endsWith(".semanticdb"))
+        .filter(!_.segments.exists(_ == "bloop-internal-classes"))
+      expect(semDbFiles.length == 1)
+      val semDbFile = semDbFiles.head
+      expect(
+        semDbFile.endsWith(os.rel / "META-INF" / "semanticdb" / "foo" / "Test.java.semanticdb")
+      )
+    }
+  }
 }

project/deps.sc

@@ -80,6 +80,7 @@ object Deps {
   def scalaPackagerCli         = ivy"org.virtuslab::scala-packager-cli:${Versions.scalaPackager}"
   def scalaparse               = ivy"com.lihaoyi::scalaparse:2.3.3"
   def scalaReflect(sv: String) = ivy"org.scala-lang:scala-reflect:$sv"
+  def semanticDbJavac          = ivy"com.sourcegraph:semanticdb-javac:0.7.4"
   def semanticDbScalac         = ivy"org.scalameta:::semanticdb-scalac:${Versions.scalaMeta}"
   def shapeless                = ivy"com.chuusai::shapeless:2.3.7"
   def slf4jNop                 = ivy"org.slf4j:slf4j-nop:1.8.0-beta4"