Support suspending extension functions

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

@@ -69,6 +69,8 @@ interface CandidateWithBoundDispatchReceiver<out D : CallableDescriptor> {
     val diagnostics: List<ResolutionDiagnostic>
 
     val dispatchReceiver: ReceiverValue?
+
+    fun copy(newDescriptor: @UnsafeVariance D): CandidateWithBoundDispatchReceiver<D>
 }
 
 data class ResolutionCandidateStatus(val diagnostics: List<ResolutionDiagnostic>) {

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

@@ -21,6 +21,8 @@ import org.jetbrains.kotlin.descriptors.FunctionDescriptor
 import org.jetbrains.kotlin.descriptors.VariableDescriptor
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
+import org.jetbrains.kotlin.resolve.coroutine.CoroutineReceiverValue
+import org.jetbrains.kotlin.resolve.coroutine.createCoroutineSuspensionFunctionView
 import org.jetbrains.kotlin.resolve.scopes.receivers.QualifierReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.Receiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
@@ -102,9 +104,23 @@ private class NoExplicitReceiverScopeTowerProcessor<D : CallableDescriptor, C: C
                     }
                 }
                 is TowerData.BothTowerLevelAndImplicitReceiver -> {
-                    data.level.collectCandidates(name, data.implicitReceiver).filter { it.requiresExtensionReceiver }.map {
-                        context.createCandidate(it, ExplicitReceiverKind.NO_EXPLICIT_RECEIVER, extensionReceiver = data.implicitReceiver)
+                    val result = mutableListOf<C>()
+
+                    data.level.collectCandidates(name, data.implicitReceiver).filter { it.requiresExtensionReceiver }.forEach {
+                        result.add(
+                            context.createCandidate(
+                                    it, ExplicitReceiverKind.NO_EXPLICIT_RECEIVER, extensionReceiver = data.implicitReceiver))
+
+                        if (data.implicitReceiver is CoroutineReceiverValue) {
+                            val newDescriptor = it.descriptor.createCoroutineSuspensionFunctionView() ?: return@forEach
+                            result.add(
+                                context.createCandidate(
+                                        it.copy(newDescriptor = newDescriptor),
+                                        ExplicitReceiverKind.NO_EXPLICIT_RECEIVER, extensionReceiver = data.implicitReceiver))
+                        }
                     }
+
+                    result
                 }
                 else -> emptyList()
             }

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

@@ -35,4 +35,7 @@ internal class CandidateWithBoundDispatchReceiverImpl<out D : CallableDescriptor
         override val dispatchReceiver: ReceiverValue?,
         override val descriptor: D,
         override val diagnostics: List<ResolutionDiagnostic>
-) : CandidateWithBoundDispatchReceiver<D>
+) : CandidateWithBoundDispatchReceiver<D> {
+    override fun copy(newDescriptor: @UnsafeVariance D) =
+            CandidateWithBoundDispatchReceiverImpl(dispatchReceiver, newDescriptor, diagnostics)
+}