Phase name match is partial

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

@@ -323,7 +323,7 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
     val phasesSettings = List("-Vphases", "-Vprint")
     for phasesSetting <- ctx.settings.allSettings if phasesSettings.contains(phasesSetting.name) do
       for case vs: List[String] <- phasesSetting.userValue; p <- vs do
-        if !phases.exists(_.phaseName == p) then report.warning(s"'$p' specifies no phase")
+        if !phases.exists(List(p).containsPhase) then report.warning(s"'$p' specifies no phase")
 
     if ctx.settings.YnoDoubleBindings.value then
       ctx.base.checkNoDoubleBindings = true

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

@@ -162,7 +162,7 @@ trait CliCommand:
       val maxCol = ctx.settings.pageWidth.value
       val field1 = maxField.min(texts.flatten.map(_._1.length).filter(_ < maxField).max) // widest field under maxField
       val field2 = if field1 + separation + maxField < maxCol then maxCol - field1 - separation else 0 // skinny window -> terminal wrap
-      val toMark = ctx.settings.XshowPhases.value.toSet
+      def toMark(name: String) = ctx.settings.Vphases.value.exists(name.contains)
       def separator(name: String) = if toMark(name) then "->" + " " * (separation - 2) else " " * separation
       val EOL = "\n"
       def formatField1(text: String): String = if text.length <= field1 then text.padLeft(field1) else text + EOL + "".padLeft(field1)

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

@@ -17,10 +17,10 @@ abstract class CompilerCommand extends CliCommand:
         else if (settings.Xhelp.value) xusageMessage
         else if (settings.Yhelp.value) yusageMessage
         else if (settings.showPlugins.value) ctx.base.pluginDescriptions
-        else if settings.XshowPhases.isPresentIn(summon[SettingsState]) then phasesMessage
+        else if settings.Vphases.isPresent then phasesMessage
         else ""
 
-  final def isHelpFlag(using settings: ConcreteSettings)(using SettingsState): Boolean =
+  final def isHelpFlag(using settings: ConcreteSettings)(using ss: SettingsState): Boolean =
     import settings.*
     val flags = Set(help, Vhelp,  Whelp, Xhelp, Yhelp, showPlugins)
-    flags.exists(_.value) || XshowPhases.isPresentIn(summon[SettingsState]) || allSettings.exists(isHelping)
+    flags.exists(_.value) || Vphases.isPresentIn(ss) || allSettings.exists(isHelping)

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

@@ -143,7 +143,7 @@ private sealed trait VerboseSettings:
   self: SettingGroup =>
   val Vhelp: Setting[Boolean] = BooleanSetting(VerboseSetting, "V", "Print a synopsis of verbose options.")
   val Vprint: Setting[List[String]] = PhasesSetting(VerboseSetting, "Vprint", "Print out program after", default = "typer", aliases = List("-Xprint"))
-  val XshowPhases: Setting[List[String]] = PhasesSetting(VerboseSetting, "Vphases", "List compiler phases.", default = "none", aliases = List("-Xshow-phases"))
+  val Vphases: Setting[List[String]] = PhasesSetting(VerboseSetting, "Vphases", "List compiler phases.", default = "none", aliases = List("-Xshow-phases"))
 
   val Vprofile: Setting[Boolean] = BooleanSetting(VerboseSetting, "Vprofile", "Show metrics about sources and internal representations to estimate compile-time complexity.")
   val VprofileSortedBy = ChoiceSetting(VerboseSetting, "Vprofile-sorted-by", "key", "Show metrics about sources and internal representations sorted by given column name", List("name", "path", "lines", "tokens", "tasty", "complexity"), "")

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

@@ -306,6 +306,7 @@ object Settings:
       def userValue(using Context): Option[T] = setting.userValueIn(ctx.settingsState)
       def update(x: T)(using Context): SettingsState = setting.updateIn(ctx.settingsState, x)
       def isDefault(using Context): Boolean = setting.isDefaultIn(ctx.settingsState)
+      def isPresent(using Context): Boolean = setting.isPresentIn(ctx.settingsState)
 
     /**
      * A choice with help description.