Add alternative subsumes implementations

This is done for comparing old with new

Author: odersky

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

@@ -93,23 +93,59 @@ trait CaptureRef extends TypeProxy, ValueType:
   final def invalidateCaches() =
     myCaptureSetRunId = NoRunId
 
+  final def subsumes(y: CaptureRef)(using Context): Boolean =
+    val was = subsumesOld(y)
+    val now = subsumesNew(y)
+    if was != now then
+      println(i"diff for  $this subsumes $y, now: $now, ${this.getClass}, ${y.getClass}")
+    was
+
+  final def subsumesOld(y: CaptureRef)(using Context): Boolean =
+    (this eq y)
+    || this.isRootCapability
+    || y.match
+        case y: TermRef =>
+            y.prefix.match
+              case ypre: CaptureRef =>
+                this.subsumesOld(ypre)
+                || this.match
+                    case x @ TermRef(xpre: CaptureRef, _) =>
+                      x.symbol == y.symbol && xpre =:= ypre
+                    case _ =>
+                      false
+              case _ => false
+          || y.info.match
+              case y1: SingletonCaptureRef => this.subsumesOld(y1)
+              case _ => false
+        case MaybeCapability(y1) => this.stripMaybe.subsumesOld(y1)
+        case _ => false
+    || this.match
+        case ReachCapability(x1) => x1.subsumesOld(y.stripReach)
+        case x: TermRef =>
+          x.info match
+            case x1: SingletonCaptureRef => x1.subsumesOld(y)
+            case _ => false
+        case x: TermParamRef => subsumesExistentially(x, y)
+        case x: TypeRef => assumedContainsOf(x).contains(y)
+        case _ => false
+
   /** x subsumes x
    *   this subsumes this.f
    *   x subsumes y  ==>  x* subsumes y, x subsumes y?
    *   x subsumes y  ==>  x* subsumes y*, x? subsumes y?
    *   x: x1.type /\ x1 subsumes y  ==>  x subsumes y
    */
-  final def subsumes(y: CaptureRef)(using Context): Boolean =
+  final def subsumesNew(y: CaptureRef)(using Context): Boolean =
     def compareCaptureRefs(x: Type, y: Type): Boolean =
       (x eq y)
       || y.match
           case y: CaptureRef => x.match
-            case x: CaptureRef => x.subsumes(y)
+            case x: CaptureRef => x.subsumesNew(y)
             case _ => false
           case _ => false
 
     def compareUndelying(x: Type): Boolean = x match
-      case x: SingletonCaptureRef => x.subsumes(y)
+      case x: SingletonCaptureRef => x.subsumesNew(y)
       case x: AndType => compareUndelying(x.tp1) || compareUndelying(x.tp2)
       case x: OrType => compareUndelying(x.tp1) && compareUndelying(x.tp2)
       case _ => false
@@ -140,11 +176,11 @@ trait CaptureRef extends TypeProxy, ValueType:
         if compareCaptureRefs(this, y.prefix) then return true
         // underlying
         if compareCaptureRefs(this, y.info) then return true
-      case MaybeCapability(y1) => return this.stripMaybe.subsumes(y1)
+      case MaybeCapability(y1) => return this.stripMaybe.subsumesNew(y1)
       case _ =>
 
     return this.match
-      case ReachCapability(x1) => x1.subsumes(y.stripReach)
+      case ReachCapability(x1) => x1.subsumesNew(y.stripReach)
       case x: TermRef => compareUndelying(x.info)
       case CapturingType(x1, _) => compareUndelying(x1)
       case x: TermParamRef => subsumesExistentially(x, y)