Warn if -Vprint is not a phase

Author: som-snytt

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

@@ -320,6 +320,10 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
     val phases = ctx.base.fusePhases(pluginPlan,
       ctx.settings.Yskip.value, ctx.settings.YstopBefore.value, stopAfter, ctx.settings.Ycheck.value)
     ctx.base.usePhases(phases, runCtx)
+    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 ctx.settings.YnoDoubleBindings.value then
       ctx.base.checkNoDoubleBindings = true
@@ -342,7 +346,7 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
             profiler.onPhase(phase):
               try units = phase.runOn(units)
               catch case _: InterruptedException => cancelInterrupted()
-            for (printAt <- ctx.settings.Xprint.userValue if printAt.containsPhase(phase))
+            for printAt <- ctx.settings.Vprint.userValue if printAt.containsPhase(phase) do
               for (unit <- units)
                 def printCtx(unit: CompilationUnit) = phase.printingContext(
                   ctx.fresh.setPhase(phase.next).setCompilationUnit(unit))

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

@@ -142,7 +142,7 @@ private sealed trait PluginSettings:
 private sealed trait VerboseSettings:
   self: SettingGroup =>
   val Vhelp: Setting[Boolean] = BooleanSetting(VerboseSetting, "V", "Print a synopsis of verbose options.")
-  val Xprint: Setting[List[String]] = PhasesSetting(VerboseSetting, "Vprint", "Print out program after", default = "typer", aliases = List("-Xprint"))
+  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 Vprofile: Setting[Boolean] = BooleanSetting(VerboseSetting, "Vprofile", "Show metrics about sources and internal representations to estimate compile-time complexity.")

compiler/src/dotty/tools/dotc/transform/Recheck.scala

@@ -176,7 +176,7 @@ abstract class Recheck extends Phase, SymTransformer:
      *  can be retrieved with `knownType`
      */
     private val keepAllTypes = inContext(ictx) {
-      ictx.settings.Xprint.value.containsPhase(thisPhase)
+      ictx.settings.Vprint.value.containsPhase(thisPhase)
     }
 
     /** Should type of `tree` be kept in an attachment so that it can be retrieved with