FIR: Support checking PRIVATE_TO_THIS visibility #KT-49875 Fixed

compiler/fir/providers/src/org/jetbrains/kotlin/fir/FirVisibilityChecker.kt

@@ -12,10 +12,12 @@ import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticPropertyAccessor
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.expressions.FirPropertyAccessExpression
+import org.jetbrains.kotlin.fir.expressions.FirThisReceiverExpression
 import org.jetbrains.kotlin.fir.references.FirSuperReference
 import org.jetbrains.kotlin.fir.resolve.*
 import org.jetbrains.kotlin.fir.resolve.calls.ExpressionReceiverValue
 import org.jetbrains.kotlin.fir.resolve.calls.FirSyntheticFunctionSymbol
+import org.jetbrains.kotlin.fir.resolve.calls.ImplicitReceiverValue
 import org.jetbrains.kotlin.fir.resolve.calls.ReceiverValue
 import org.jetbrains.kotlin.fir.resolve.providers.firProvider
 import org.jetbrains.kotlin.fir.resolve.providers.symbolProvider
@@ -243,8 +245,9 @@ abstract class FirVisibilityChecker : FirSessionComponent {
         }
 
         if (dispatchReceiver != null) {
+            val fir = symbol.fir
             val dispatchReceiverParameterClassSymbol =
-                (symbol.fir as? FirCallableDeclaration)
+                (fir as? FirCallableDeclaration)
                     ?.propertyIfAccessor?.propertyIfBackingField
                     ?.dispatchReceiverClassOrNull()?.toSymbol(session)
                     ?: return true
@@ -260,6 +263,24 @@ abstract class FirVisibilityChecker : FirSessionComponent {
                 )
 
             if (dispatchReceiverParameterClassLookupTag != dispatchReceiverValueOwnerLookupTag) return false
+            if (fir.visibility == Visibilities.PrivateToThis) {
+                when (dispatchReceiver) {
+                    is ExpressionReceiverValue -> {
+                        val explicitReceiver = dispatchReceiver.explicitReceiver
+                        if (explicitReceiver !is FirThisReceiverExpression) {
+                            return false
+                        }
+                        if (explicitReceiver.calleeReference.boundSymbol != dispatchReceiverParameterClassSymbol) {
+                            return false
+                        }
+                    }
+                    is ImplicitReceiverValue<*> -> {
+                        if (dispatchReceiver.boundSymbol != dispatchReceiverParameterClassSymbol) {
+                            return false
+                        }
+                    }
+                }
+            }
         }
 
         for (declaration in containingDeclarationOfUseSite) {