Option warnings are conditional

Author: som-snytt

compiler/src/dotty/tools/dotc/config/CliCommand.scala

@@ -150,7 +150,7 @@ trait CliCommand:
    */
   def checkUsage(summary: ArgsSummary, sourcesRequired: Boolean)(using settings: ConcreteSettings)(using SettingsState, Context): Option[List[String]] =
     // Print all warnings encountered during arguments parsing
-    summary.warnings.foreach(report.warning(_))
+    summary.warnings.foreach(report.configurationWarning(_))
 
     if summary.errors.nonEmpty then
       summary.errors foreach (report.error(_))

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -98,6 +98,7 @@ trait CommonScalaSettings:
   val silentWarnings: Setting[Boolean] = BooleanSetting("-nowarn", "Silence all warnings.", aliases = List("--no-warnings"))
 
   val release: Setting[String] = ChoiceSetting("-release", "release", "Compile code with classes specific to the given version of the Java platform available on the classpath and emit bytecode for this version.", ScalaSettings.supportedReleaseVersions, "", aliases = List("--release"))
+  val configuration: Setting[Boolean] = BooleanSetting("-configuration", "Warn about conflicting and redundant tool options", aliases = List("--configuration"))
   val deprecation: Setting[Boolean] = BooleanSetting("-deprecation", "Emit warning and location for usages of deprecated APIs.", aliases = List("--deprecation"))
   val feature: Setting[Boolean] = BooleanSetting("-feature", "Emit warning and location for usages of features that should be imported explicitly.", aliases = List("--feature"))
   val explain: Setting[Boolean] = BooleanSetting("-explain", "Explain errors in more detail.", aliases = List("--explain"))

compiler/src/dotty/tools/dotc/report.scala

@@ -23,6 +23,9 @@ object report:
   private def issueWarning(warning: Warning)(using Context): Unit =
     ctx.reporter.report(warning)
 
+  def configurationWarning(msg: Message, pos: SrcPos = NoSourcePosition)(using Context): Unit =
+    issueWarning(ConfigurationWarning(msg, pos.sourcePos))
+
   def deprecationWarning(msg: Message, pos: SrcPos = NoSourcePosition)(using Context): Unit =
     issueWarning(new DeprecationWarning(msg, pos.sourcePos))
 
@@ -112,4 +115,4 @@ object report:
       case Nil => pos
     recur(pos.sourcePos, tpd.enclosingInlineds)
 
-end report
+end report

compiler/src/dotty/tools/dotc/reporting/Diagnostic.scala

@@ -75,6 +75,13 @@ object Diagnostic:
     def enablingOption(using Context): Setting[Boolean] = ctx.settings.deprecation
   }
 
+  class ConfigurationWarning(
+    msg: Message,
+    pos: SourcePosition
+  ) extends ConditionalWarning(msg, pos) {
+    def enablingOption(using Context): Setting[Boolean] = ctx.settings.configuration
+  }
+
   class MigrationWarning(
     msg: Message,
     pos: SourcePosition

compiler/src/dotty/tools/dotc/reporting/Reporter.scala

@@ -201,22 +201,21 @@ abstract class Reporter extends interfaces.ReporterResult {
     incompleteHandler(dia, ctx)
 
   /** Summary of warnings and errors */
-  def summary: String = {
-    val b = new mutable.ListBuffer[String]
+  def summary: String =
+    val b = mutable.ListBuffer.empty[String]
     if (warningCount > 0)
       b += countString(warningCount, "warning") + " found"
     if (errorCount > 0)
       b += countString(errorCount, "error") + " found"
     for ((settingName, count) <- unreportedWarnings)
       b += s"there were $count ${settingName.tail} warning(s); re-run with $settingName for details"
     b.mkString("\n")
-  }
 
   /** Print the summary of warnings and errors */
-  def printSummary(using Context): Unit = {
-    val s = summary
-    if (s != "") report(new Info(s, NoSourcePosition))
-  }
+  def printSummary(using Context): Unit =
+    summary match
+      case "" =>
+      case s  => report(Info(s, NoSourcePosition))
 
   /** Returns a string meaning "n elements". */
   protected def countString(n: Int, elements: String): String = n match {

compiler/src/dotty/tools/dotc/reporting/WConf.scala

@@ -13,6 +13,7 @@ import scala.util.matching.Regex
 enum MessageFilter:
   def matches(message: Diagnostic): Boolean = this match
     case Any => true
+    case Configuration => message.isInstanceOf[Diagnostic.ConfigurationWarning]
     case Deprecated => message.isInstanceOf[Diagnostic.DeprecationWarning]
     case Feature => message.isInstanceOf[Diagnostic.FeatureWarning]
     case Unchecked => message.isInstanceOf[Diagnostic.UncheckedWarning]
@@ -22,7 +23,7 @@ enum MessageFilter:
     case MessageID(errorId) => message.msg.errorId == errorId
     case None => false
 
-  case Any, Deprecated, Feature, Unchecked, None
+  case Any, Configuration, Deprecated, Feature, Unchecked, None
   case MessagePattern(pattern: Regex)
   case MessageID(errorId: ErrorMessageID)
 
@@ -78,10 +79,11 @@ object WConf:
         catch case _: IllegalArgumentException => Left(s"unknown error message name: $conf")
 
       case "cat" => conf match
-        case "deprecation" => Right(Deprecated)
-        case "feature"     => Right(Feature)
-        case "unchecked"   => Right(Unchecked)
-        case _             => Left(s"unknown category: $conf")
+        case "configuration" => Right(Configuration)
+        case "deprecation"   => Right(Deprecated)
+        case "feature"       => Right(Feature)
+        case "unchecked"     => Right(Unchecked)
+        case _               => Left(s"unknown category: $conf")
       case _ => Left(s"unknown filter: $filter")
     case _ => Left(s"unknown filter: $s")