Option warnings are conditional

Author: som-snytt

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

@@ -123,7 +123,7 @@ 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

@@ -108,6 +108,7 @@ trait CommonScalaSettings:
   val javaOutputVersion: Setting[String] = ChoiceSetting("-java-output-version", "version", "Compile code with classes specific to the given version of the Java platform available on the classpath and emit bytecode for this version. Corresponds to -release flag in javac.", ScalaSettings.supportedReleaseVersions, "", aliases = List("-release", "--release"))
   val scalaOutputVersion: Setting[String] = ChoiceSetting("-scala-output-version", "version", "Emit TASTy files that can be consumed by specified version of the compiler. The compilation will fail if for any reason valid TASTy cannot be produced (e.g. the code contains references to some parts of the standard library API that are missing in the older stdlib or uses language features unexpressible in the older version of TASTy format)", ScalaSettings.supportedScalaReleaseVersions, "")
 
+  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))
 

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

@@ -77,6 +77,13 @@ 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

@@ -205,14 +205,13 @@ 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"
     b.mkString("\n")
-  }
 
   def summarizeUnreportedWarnings(using Context): Unit =
     for (settingName, count) <- unreportedWarnings do
@@ -221,10 +220,10 @@ abstract class Reporter extends interfaces.ReporterResult {
       report(Warning(msg, NoSourcePosition))
 
   /** 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

@@ -14,6 +14,7 @@ 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]
@@ -23,7 +24,7 @@ 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)
 
@@ -79,10 +80,11 @@ 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")