Code cleanup: type parameters can have in / out variance

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/ScopeTowerProcessors.kt

@@ -27,14 +27,14 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
 import org.jetbrains.kotlin.utils.addToStdlib.check
 
 
-class KnownResultProcessor<C>(
+class KnownResultProcessor<out C>(
         val result: Collection<C>
 ): ScopeTowerProcessor<C> {
     override fun process(data: TowerData)
             = if (data == TowerData.Empty) listOfNotNull(result.check { it.isNotEmpty() }) else emptyList()
 }
 
-class CompositeScopeTowerProcessor<C>(
+class CompositeScopeTowerProcessor<out C>(
         vararg val processors: ScopeTowerProcessor<C>
 ) : ScopeTowerProcessor<C> {
     override fun process(data: TowerData): List<Collection<C>> = processors.flatMap { it.process(data) }

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/TowerResolver.kt

@@ -38,7 +38,7 @@ interface Candidate<out D : CallableDescriptor> {
     val status: ResolutionCandidateStatus
 }
 
-interface TowerContext<D : CallableDescriptor, C: Candidate<D>> {
+interface TowerContext<D : CallableDescriptor, out C: Candidate<D>> {
     val name: Name
     val scopeTower: ScopeTower
 

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/TowerUtils.kt

@@ -31,7 +31,7 @@ val CandidateWithBoundDispatchReceiver<*>.requiresExtensionReceiver: Boolean
 
 fun DataFlowDecorator.getAllPossibleTypes(receiver: ReceiverValue) = getSmartCastTypes(receiver) + receiver.type
 
-internal class CandidateWithBoundDispatchReceiverImpl<D : CallableDescriptor>(
+internal class CandidateWithBoundDispatchReceiverImpl<out D : CallableDescriptor>(
         override val dispatchReceiver: ReceiverValue?,
         override val descriptor: D,
         override val diagnostics: List<ResolutionDiagnostic>