Warn if -Vprint is not a phase

Author: som-snytt

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

@@ -345,6 +345,10 @@ extends ImplicitRunInfo, ConstraintRunInfo, cc.CaptureRunInfo {
     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
@@ -367,7 +371,7 @@ extends ImplicitRunInfo, ConstraintRunInfo, cc.CaptureRunInfo {
             profiler.onPhase(phase):
               try units = phase.runOn(units)
               catch case _: InterruptedException => cancelInterrupted()
-            for (printAt <- ctx.settings.Vprint.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))