Add captDebug printer

Author: odersky

compiler/src/dotty/tools/dotc/cc/CaptureSet.scala

@@ -529,20 +529,19 @@ object CaptureSet:
 
     private def levelOK(elem: CaptureRef)(using Context): Boolean =
       if elem.isUniversalRootCapability then !noUniversal
-      else if elem.isInstanceOf[TermParamRef] then
-        //println(i"can't include $elem in $this")
-        //new Error().printStackTrace()
-        !ctx.settings.YccNew.value
-      else !levelLimit.exists
-        || elem.match
-            case elem: TermRef =>
-              var sym = elem.symbol
-              if sym.isLevelOwner then sym = sym.owner
-              levelLimit.isContainedIn(sym.levelOwner)
-            case elem: ThisType =>
-              levelLimit.isContainedIn(elem.cls.levelOwner)
-            case _ =>
-              true
+      else elem match
+        case elem: TermRef =>
+          if levelLimit.exists then
+            var sym = elem.symbol
+            if sym.isLevelOwner then sym = sym.owner
+            levelLimit.isContainedIn(sym.levelOwner)
+          else true
+        case elem: ThisType =>
+          if levelLimit.exists then
+            levelLimit.isContainedIn(elem.cls.levelOwner)
+          else true
+        case elem: TermParamRef =>
+          true
 
     def addDependent(cs: CaptureSet)(using Context, VarState): CompareResult =
       if (cs eq this) || cs.isUniversal || isConst then

compiler/src/dotty/tools/dotc/cc/Setup.scala

@@ -8,7 +8,7 @@ import Contexts.*, Names.*, Flags.*, Symbols.*, Decorators.*
 import Types.*, StdNames.*
 import Annotations.Annotation
 import config.Feature
-import config.Printers.capt
+import config.Printers.{capt, captDebug}
 import ast.tpd, tpd.*
 import transform.{PreRecheck, Recheck}, Recheck.*
 import CaptureSet.{IdentityCaptRefMap, IdempotentCaptRefMap}
@@ -595,7 +595,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
         needsVariable(parent)
       case _ =>
         false
-  }.showing(i"can have inferred capture $tp = $result", capt)
+  }.showing(i"can have inferred capture $tp = $result", captDebug)
 
   /** Pull out an embedded capture set from a part of `tp` */
   def normalizeCaptures(tp: Type)(using Context): Type = tp match

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

@@ -22,6 +22,10 @@ object Printers {
     if ctx.settings.YccLog.value then captActive else noPrinter
   val captActive = new Printer
 
+  def captDebug(using Context): Printer =
+    if ctx.settings.YccDebug.value then captDebugActive else noPrinter
+  val captDebugActive = new Printer
+
   val constr = noPrinter
   val core = noPrinter
   val checks = noPrinter

compiler/src/dotty/tools/dotc/core/ConstraintHandling.scala

@@ -54,7 +54,7 @@ trait ConstraintHandling {
   protected var homogenizeArgs: Boolean = false
 
   /** We are currently comparing type lambdas. Used as a flag for
-   *  optimization: when `false`, no need to do an expensive `pruneLambdaParams`
+   *  optimization: when `false`, no need to do an expensive `avoidLambdaParams`
    */
   protected var comparedTypeLambdas: Set[TypeLambda] = Set.empty