scalafixEnable: support builds overriding scalacOptions

Also, scalacOptions are now set in a more specific scope (matching the
one looked up for compiler invocation so that scalafixEnable overrides
them no matter at which scope they are defined), so assertions had to
be updated.

src/main/scala-sbt-0.13/sbt/internal/sbtscalafix/Compat.scala

@@ -1,6 +1,6 @@
 package sbt.internal.sbtscalafix
 
-import sbt.{Compiler, Extracted, Setting, State}
+import sbt.{Classpaths, Compiler, Extracted, Setting, State, UpdateReport}
 import sbt.inc.IncOptions
 
 object Compat {
@@ -30,4 +30,15 @@ object Compat {
   ): Compiler.CompileResult = {
     compileResult
   }
+
+  def autoPlugins(
+      report: UpdateReport,
+      scalaVersion: String
+  ): Seq[String] = {
+    Classpaths.autoPlugins(
+      report,
+      Seq(),
+      Set("jar", "bundle")
+    )
+  }
 }

src/main/scala-sbt-1.0/sbt/internal/sbtscalafix/Compat.scala

@@ -1,6 +1,7 @@
 package sbt.internal.sbtscalafix
 
-import sbt.{Extracted, IncOptions, Setting, State}
+import sbt.internal.inc.ScalaInstance
+import sbt.{Classpaths, Extracted, IncOptions, Setting, State, UpdateReport}
 import xsbti.compile.CompileResult
 
 object Compat {
@@ -32,4 +33,15 @@ object Compat {
   ): CompileResult = {
     compileResult.withHasModified(hasModified)
   }
+
+  def autoPlugins(
+      report: UpdateReport,
+      scalaVersion: String
+  ): Seq[String] = {
+    Classpaths.autoPlugins(
+      report,
+      Seq(),
+      ScalaInstance.isDotty(scalaVersion)
+    )
+  }
 }

src/main/scala/scalafix/sbt/ScalafixEnable.scala

@@ -36,11 +36,14 @@ object ScalafixEnable {
       "Configure libraryDependencies, scalaVersion and scalacOptions for scalafix.",
     detail = """1. enables the semanticdb-scalac compiler plugin
       |2. sets scalaVersion to latest Scala version supported by scalafix
-      |3. add -Yrangepos to scalacOptions""".stripMargin
+      |3. add -Yrangepos to Compile|Test / compile / scalacOptions""".stripMargin
   ) { s =>
     val extracted = Project.extract(s)
-    val relaxScalacForScalafix = Seq(Compile, Test).flatMap(
-      inConfig(_)(ScalafixPlugin.relaxScalacOptionsConfigSettings)
+    val scalacOptionsSettings = Seq(Compile, Test).flatMap(
+      inConfig(_)(
+        semanticdbConfigSettings ++
+          ScalafixPlugin.relaxScalacOptionsConfigSettings
+      )
     )
     val settings: Seq[Setting[_]] = for {
       (p, fullVersion) <- projectsWithMatchingScalaVersion(s)
@@ -49,23 +52,33 @@ object ScalafixEnable {
           .in(p)
           .get(extracted.structure.data)
           .exists(_.exists(_.name == "semanticdb-scalac"))
-      addSemanticdb <- List(
+      addSemanticdbCompilerPlugin <- List(
         scalaVersion.in(p) := fullVersion,
-        scalacOptions.in(p) ++= List(
-          "-Yrangepos",
-          s"-Xplugin-require:semanticdb"
-        ),
         libraryDependencies.in(p) += compilerPlugin(
           ScalafixPlugin.autoImport.scalafixSemanticdb
         )
       )
       settings <-
-        inScope(ThisScope.in(p))(relaxScalacForScalafix) ++
-          (if (!isSemanticdbEnabled) addSemanticdb else List())
+        inScope(ThisScope.in(p))(scalacOptionsSettings) ++
+          (if (!isSemanticdbEnabled) addSemanticdbCompilerPlugin else List())
     } yield settings
 
     val scalafixReady = Compat.append(extracted, settings, s)
 
     scalafixReady
   }
+
+  private val semanticdbConfigSettings: Seq[Def.Setting[_]] =
+    Seq(
+      scalacOptions.in(compile) := {
+        val old = scalacOptions.in(compile).value
+        val options = List(
+          "-Yrangepos",
+          "-Xplugin-require:semanticdb"
+        )
+        // don't rely on autoCompilerPlugins to inject the plugin as it does not work if scalacOptions is overriden in the build
+        val plugins = Compat.autoPlugins(update.value, scalaVersion.value)
+        old ++ (plugins ++ options).diff(old)
+      }
+    )
 }

src/sbt-test/sbt-scalafix/scalafixEnable/build.sbt

@@ -33,14 +33,34 @@ TaskKey[Unit]("check") := {
   // nothing should change for the 2.10 project
   assert(scalaVersion.in(scala210).value == "2.10.4")
   assert(libraryDependencies.in(scala210).value.isEmpty)
-  assert(scalacOptions.in(scala210).value.isEmpty)
+  assert(scalacOptions.in(scala210, Compile, compile).value.isEmpty)
 
   // 2.12.0 should be overidden to 2.12.X
   assert(scalaVersion.in(overridesSettings).value == V.scala212)
   assert(libraryDependencies.in(overridesSettings).value.nonEmpty)
-  assert(scalacOptions.in(overridesSettings).value.contains("-Yrangepos"))
+  assert(
+    scalacOptions
+      .in(overridesSettings, Compile, compile)
+      .value
+      .contains("-Yrangepos")
+  )
 
-  assert(scalacOptions.in(scala211).value.count(_ == "-Yrangepos") == 1)
-  assert(scalacOptions.in(scala212).value.count(_ == "-Yrangepos") == 1)
-  assert(scalacOptions.in(scala213).value.count(_ == "-Yrangepos") == 1)
+  assert(
+    scalacOptions
+      .in(scala211, Compile, compile)
+      .value
+      .count(_ == "-Yrangepos") == 1
+  )
+  assert(
+    scalacOptions
+      .in(scala212, Compile, compile)
+      .value
+      .count(_ == "-Yrangepos") == 1
+  )
+  assert(
+    scalacOptions
+      .in(scala213, Test, compile)
+      .value
+      .count(_ == "-Yrangepos") == 1
+  )
 }

src/sbt-test/sbt-scalafix/scalafixEnable/project/FatalWarningsPlugin.scala

@@ -12,7 +12,7 @@ object FatalWarningsPlugin extends AutoPlugin {
   override def requires: Plugins = ScalafixPlugin
 
   override def projectSettings: Seq[Def.Setting[_]] = Seq(
-    scalacOptions.in(Test, compile) ++= Seq(
+    scalacOptions.in(Test, compile) := Seq(
       "-Xfatal-warnings",
       "-Ywarn-unused"
     )