Remove LintID.owner.

Instead of using LintID.owner, the RewriteCtx.printMessages takes an
`owner: RewriteName` argument. This results  in a simpler LintID data
structure.

scalafix-core/shared/src/main/scala/scalafix/internal/config/LintConfig.scala

@@ -22,12 +22,12 @@ case class LintConfig(
       ).map { case ((((a, b), c), d), e) => LintConfig(a, b, c, d, e) }
     }
 
-  def getCategory(id: LintID): LintCategory = id.key match {
-    case error() => LintCategory.Error
-    case warning() => LintCategory.Warning
-    case info() => LintCategory.Info
-    case _ => id.category
-  }
+  def getConfiguredCategory(key: String): Option[LintCategory] =
+    Option(key).collect {
+      case error() => LintCategory.Error
+      case warning() => LintCategory.Warning
+      case info() => LintCategory.Info
+    }
 }
 
 object LintConfig {

scalafix-core/shared/src/main/scala/scalafix/lint/LintCategory.scala

@@ -20,4 +20,4 @@ object LintCategory {
   case object Info extends LintCategory
   case object Warning extends LintCategory
   case object Error extends LintCategory
-}
+}

scalafix-core/shared/src/main/scala/scalafix/lint/LintID.scala

@@ -7,22 +7,18 @@ import scala.meta.inputs.Position
   *
   * @param id a string ID for this message, typically the name of the
   *           assigned variable.
-  * @param owner The rewrite that owns this lint message, to distinguish
-  *              lint messages with conflicting IDs from different rewrites.
   * @param explanation An optional explanation for this kind of message.
   * @param category The default category this message should get reported to.
   *                 Note that users can configure/override the default category.
   */
 final case class LintID(
     id: String,
-    owner: RewriteName,
     explanation: String,
     category: LintCategory
 ) {
-  override def toString: String = key
-  lazy val key = s"$owner.$id"
+  def key(owner: RewriteName) = s"$owner.$id"
   private def noExplanation: LintID =
-    new LintID(id, owner, explanation, category)
+    new LintID(id, explanation, category)
   def at(message: String, position: Position): LintMessage =
     LintMessage(message, position, this)
   def at(message: String): LintMessage =
@@ -33,9 +29,9 @@ final case class LintID(
 
 object LintID {
   def error(explain: String)(implicit alias: sourcecode.Name): LintID =
-    new LintID(alias.value, RewriteName.empty, explain, LintCategory.Error)
+    new LintID(alias.value, explain, LintCategory.Error)
   def warning(explain: String)(
       implicit alias: sourcecode.Name,
       rewrite: RewriteName): LintID =
-    new LintID(alias.value, RewriteName.empty, explain, LintCategory.Warning)
+    new LintID(alias.value, explain, LintCategory.Warning)
 }

scalafix-core/shared/src/main/scala/scalafix/lint/LintMessage.scala

@@ -1,6 +1,7 @@
 package scalafix.lint
 
 import scala.meta.Position
+import scalafix.rewrite.RewriteName
 
 /** An instance of a LintID with a custom message at a particular position
   *
@@ -15,14 +16,14 @@ final case class LintMessage(
     position: Position,
     id: LintID
 ) {
-  def format(explain: Boolean): String = {
+  def format(owner: RewriteName, explain: Boolean): String = {
     val explanation =
       if (explain)
         s"""
            |Explanation:
            |${id.explanation}
            |""".stripMargin
       else ""
-    s"[${id.owner.name}.${id.id}] $message$explanation"
+    s"[${owner.name}.${id.id}] $message$explanation"
   }
 }

scalafix-core/shared/src/main/scala/scalafix/patch/Patch.scala

@@ -89,9 +89,7 @@ private[scalafix] object TreePatch {
 }
 
 // implementation detail
-private[scalafix] case class LintPatch(
-    message: LintMessage
-) extends Patch
+private[scalafix] case class LintPatch(message: LintMessage) extends Patch
 private[scalafix] case class Concat(a: Patch, b: Patch) extends Patch
 private[scalafix] case object EmptyPatch extends Patch with LowLevelPatch
 
@@ -116,6 +114,9 @@ object Patch {
     case (rem: Remove, rem2: Remove) => rem
     case _ => throw Failure.TokenPatchMergeError(a, b)
   }
+  // Patch.apply and Patch.lintMessages package private. Feel free to use them
+  // for your application, but please ask on the Gitter channel to see if we
+  // can expose a better api for your use case.
   private[scalafix] def apply(
       p: Patch,
       ctx: RewriteCtx,

scalafix-core/shared/src/main/scala/scalafix/rewrite/Rewrite.scala

@@ -34,7 +34,8 @@ abstract class Rewrite(implicit val rewriteName: RewriteName) { self =>
   final def apply(ctx: RewriteCtx, patch: Patch): String = {
     val result = Patch(patch, ctx, semanticOption)
     Patch.lintMessages(patch, ctx).foreach { msg =>
-      ctx.printLintMessage(msg.copy(id = msg.id.copy(owner = rewriteName)))
+        // Set the
+      ctx.printLintMessage(msg, rewriteName)
     }
     result
   }

scalafix-core/shared/src/main/scala/scalafix/rewrite/RewriteCtx.scala

@@ -50,12 +50,15 @@ case class RewriteCtx(tree: Tree, config: ScalafixConfig) extends PatchOps {
     logger.elem(values: _*)
   }
 
-  def printLintMessage(msg: LintMessage): Unit = {
-    if (config.lint.ignore.matches(msg.id.key)) ()
+  def printLintMessage(msg: LintMessage, owner: RewriteName): Unit = {
+    val key = msg.id.key(owner)
+    if (config.lint.ignore.matches(key)) ()
     else {
-      val category = config.lint.getCategory(msg.id)
+      val category = config.lint
+        .getConfiguredCategory(key)
+        .getOrElse(msg.id.category)
       reporter.handleMessage(
-        msg.format(config.lint.explain),
+        msg.format(owner, config.lint.explain),
         msg.position,
         category.toSeverity
       )

scalafix-testkit/src/main/scala/scalafix/testkit/SemanticRewriteSuite.scala

@@ -96,7 +96,9 @@ abstract class SemanticRewriteSuite(
         }.mkString
       }
       if (lintMessages.nonEmpty) {
-        Patch.lintMessages(patch, ctx).foreach(ctx.printLintMessage)
+        Patch
+          .lintMessages(patch, ctx)
+          .foreach(x => ctx.printLintMessage(x, rewrite.rewriteName))
         val explanation =
           """To fix this problem, suffix the culprit lines with
             |   // scalafix: warning