JVM_IR: cast bound property receivers to original type

Because the receiver type is used for determining where to put
accessors, and the type of fake overrides' receivers is the same as for
the original declaration, casting to the type of the parameter leads to
assertion errors.

 #KT-44658 Fixed

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt

@@ -342,6 +342,7 @@ private class PropertyReferenceLowering(val context: JvmBackendContext) : IrElem
             referenceClass.addOverride(getSignature) { computeSignatureString(expression) }
         }
 
+        val boundReceiver = expression.getBoundReceiver()
         val backingField = superClass.properties.single { it.name.asString() == "receiver" }.backingField!!
         val get = superClass.functions.find { it.name.asString() == "get" }
         val set = superClass.functions.find { it.name.asString() == "set" }
@@ -350,20 +351,20 @@ private class PropertyReferenceLowering(val context: JvmBackendContext) : IrElem
         val field = expression.field?.owner
         if (field == null) {
             fun IrBuilderWithScope.setCallArguments(call: IrCall, arguments: List<IrValueParameter>) {
-                var index = 1
+                val receiverFromField = boundReceiver?.let { irImplicitCast(irGetField(irGet(arguments[0]), backingField), it.type) }
                 call.copyTypeArgumentsFrom(expression)
-                val hasBoundReceiver = expression.getBoundReceiver() != null
                 call.dispatchReceiver = call.symbol.owner.dispatchReceiverParameter?.let {
-                    if (hasBoundReceiver)
-                        irImplicitCast(irGetField(irGet(arguments[0]), backingField), it.type)
-                    else
-                        irImplicitCast(irGet(arguments[index++]), it.type)
+                    // TODO: in `C::x`, the receiver must be cast to `C` in order to put accessors for protected
+                    //   properties in the correct class (box/syntheticAccessors/accessorForProtectedPropertyReference.kt).
+                    //   Since there is no information about `C` in `IrPropertyReference`, we rely on fake overrides here
+                    //   (expecting that the getter is `C.getX` and not `<some superclass>.getX`) and that does not work with FIR.
+                    receiverFromField ?: irImplicitCast(irGet(arguments[1]), call.symbol.owner.parentAsClass.defaultType)
                 }
                 call.extensionReceiver = call.symbol.owner.extensionReceiverParameter?.let {
-                    if (hasBoundReceiver)
-                        irImplicitCast(irGetField(irGet(arguments[0]), backingField), it.type)
+                    if (call.symbol.owner.dispatchReceiverParameter == null)
+                        receiverFromField ?: irImplicitCast(irGet(arguments[1]), it.type)
                     else
-                        irImplicitCast(irGet(arguments[index++]), it.type)
+                        irImplicitCast(irGet(arguments[if (receiverFromField != null) 1 else 2]), it.type)
                 }
             }