Rework doc and repl scalacOptions (spotify#3653)

Author: regadas

build.sbt

@@ -144,8 +144,7 @@ val commonSettings = Def
     scalaVersion := "2.13.5",
     crossScalaVersions := Seq("2.12.13", scalaVersion.value),
     scalacOptions ++= Scalac.commonsOptions.value,
-    Compile / doc / scalacOptions --= Seq("-release", "8"),
-    Compile / doc / scalacOptions ++= Scalac.compileDocOptions.value,
+    Compile / doc / scalacOptions := Scalac.docOptions.value,
     javacOptions ++= Seq("-source", "1.8", "-target", "1.8", "-Xlint:unchecked"),
     javacOptions in (Compile, doc) := Seq("-source", "1.8"),
     // protobuf-lite is an older subset of protobuf-java and causes issues
@@ -978,7 +977,7 @@ lazy val `scio-repl`: Project = project
   .settings(assemblySettings)
   .settings(macroSettings)
   .settings(
-    scalacOptions --= Seq("-release", "8"),
+    scalacOptions := Scalac.replOptions.value,
     libraryDependencies ++= Seq(
       "org.scala-lang.modules" %% "scala-collection-compat" % scalaCollectionCompatVersion,
       "org.apache.beam" % "beam-runners-direct-java" % beamVersion,

project/ScalacOptions.scala

@@ -22,7 +22,7 @@ object Scalac {
   // see: https://tpolecat.github.io/2017/04/25/scalac-flags.html
   val parallelism = math.min(math.max(4, java.lang.Runtime.getRuntime().availableProcessors()), 16)
   val baseOptions = Def.setting {
-    val base = List(
+    List(
       "-target:jvm-1.8",
       "-deprecation", // Emit warning and location for usages of deprecated APIs.
       "-feature", // Emit warning and location for usages of features that should be imported explicitly.
@@ -63,11 +63,6 @@ object Scalac {
       "-Ybackend-parallelism",
       parallelism.toString
     )
-
-    VersionNumber(sys.props("java.version")) match {
-      case v if v.matchesSemVer(SemanticSelector(">1.8")) => base ++ List("-release", "8")
-      case _                                              => base
-    }
   }
 
   val scalaVersionOptions = Def.setting {
@@ -93,14 +88,26 @@ object Scalac {
     }
   }
 
-  val commonsOptions = Def.setting(baseOptions.value ++ scalaVersionOptions.value)
+  val jvmVersionOptions = Def.setting {
+    VersionNumber(sys.props("java.version")) match {
+      case v if v.matchesSemVer(SemanticSelector(">1.8")) => List("-release", "8")
+      case _                                              => Nil
+    }
+  }
+
+  val commonsOptions =
+    Def.setting(baseOptions.value ++ scalaVersionOptions.value ++ jvmVersionOptions.value)
 
-  val compileDocOptions = Def.setting {
-    val base = List("-skip-packages", "org.apache")
+  val docOptions = Def.setting {
+    val base =
+      baseOptions.value ++ scalaVersionOptions.value ++ List("-skip-packages", "org.apache")
 
     VersionNumber(scalaVersion.value) match {
       case v if v.matchesSemVer(SemanticSelector("2.12.x")) => base ++ List("-no-java-comments")
       case _                                                => base
     }
   }
+
+  val replOptions = Def.setting(baseOptions.value ++ scalaVersionOptions.value)
+
 }