Cast Set to Collection to choose right overload of plus.

compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/instructions/eval/accessInstructions.kt

@@ -99,7 +99,7 @@ public class WriteValueInstruction(
         public val rValue: PseudoValue
 ) : AccessValueInstruction(assignment, lexicalScope, target, receiverValues) {
     override val inputValues: List<PseudoValue>
-        get() = receiverValues.keySet() + rValue
+        get() = (receiverValues.keySet() as Collection<PseudoValue>) + rValue
 
     override fun accept(visitor: InstructionVisitor) {
         visitor.visitWriteValue(this)

compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/instructions/eval/operationInstructions.kt

@@ -59,7 +59,7 @@ public class CallInstruction private constructor(
         val resolvedCall: ResolvedCall<*>,
         override val receiverValues: Map<PseudoValue, ReceiverValue>,
         public val arguments: Map<PseudoValue, ValueParameterDescriptor>
-) : OperationInstruction(element, lexicalScope, receiverValues.keySet() + arguments.keySet()), InstructionWithReceivers {
+) : OperationInstruction(element, lexicalScope, (receiverValues.keySet() as Collection<PseudoValue>) + arguments.keySet()), InstructionWithReceivers {
     public constructor (
             element: JetElement,
             lexicalScope: LexicalScope,