IR: make calls with explicit singleton receiver tailrec [KT-48602]

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/TailRecursionCallsCollector.kt

@@ -16,11 +16,14 @@
 
 package org.jetbrains.kotlin.backend.common
 
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrFunction
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.types.IrSimpleType
+import org.jetbrains.kotlin.ir.types.classOrNull
 import org.jetbrains.kotlin.ir.types.isUnit
 import org.jetbrains.kotlin.ir.util.usesDefaultArguments
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
@@ -107,6 +110,13 @@ fun collectTailRecursionCalls(irFunction: IrFunction): Set<IrCall> {
                 // Overridden functions using default arguments at tail call are not included: KT-4285
                 return
             }
+            val dispatchReceiverType = irFunction.dispatchReceiverParameter?.type
+            if (dispatchReceiverType?.classOrNull?.owner?.kind?.isSingleton == true) {
+                // Dispatch receiver type is singleton and hence it can't be changed and the call must be tailrec.
+                result.add(expression)
+                return
+            }
+
 
             expression.dispatchReceiver?.let {
                 if (it !is IrGetValue || it.symbol.owner != irFunction.dispatchReceiverParameter) {