Add additional visibility check for synthetic extensions

Use extension receiver as dispatch one, because it is effectively dispatch
(after some desugaring)

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/checkers/ProtectedSyntheticExtensionCallChecker.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.resolve.jvm.checkers
+
+import org.jetbrains.kotlin.descriptors.Visibilities
+import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.resolve.calls.checkers.CallChecker
+import org.jetbrains.kotlin.resolve.calls.context.BasicCallResolutionContext
+import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
+import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
+import org.jetbrains.kotlin.resolve.calls.smartcasts.getReceiverValueWithSmartCast
+import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
+import org.jetbrains.kotlin.synthetic.SamAdapterExtensionFunctionDescriptor
+import org.jetbrains.kotlin.synthetic.SyntheticJavaPropertyDescriptor
+
+object ProtectedSyntheticExtensionCallChecker : CallChecker {
+    override fun check(resolvedCall: ResolvedCall<*>, context: BasicCallResolutionContext) {
+        val descriptor = resolvedCall.resultingDescriptor
+
+        val sourceFunction = when (descriptor) {
+            is SyntheticJavaPropertyDescriptor -> descriptor.getMethod
+            is SamAdapterExtensionFunctionDescriptor -> descriptor.sourceFunction
+            else -> return
+        }
+
+        val from = context.scope.ownerDescriptor
+
+        // Already reported
+        if (!Visibilities.isVisibleIgnoringReceiver(descriptor, from)) return
+
+        if (resolvedCall.dispatchReceiver != null && resolvedCall.extensionReceiver !is ReceiverValue) return
+
+        val receiverValue = resolvedCall.extensionReceiver as ReceiverValue
+        val receiverTypes = listOf(receiverValue.type) + context.dataFlowInfo.getPredictableTypes(
+                DataFlowValueFactory.createDataFlowValue(receiverValue, context))
+
+        if (receiverTypes.none { Visibilities.isVisible(getReceiverValueWithSmartCast(null, it), sourceFunction, from) }) {
+            context.trace.report(Errors.INVISIBLE_MEMBER.on(resolvedCall.call.callElement, descriptor, descriptor.visibility, from))
+        }
+    }
+}

compiler/frontend.java/src/org/jetbrains/kotlin/resolve/jvm/platform/JvmPlatformConfigurator.kt

@@ -51,7 +51,8 @@ object JvmPlatformConfigurator : PlatformConfigurator(
                 ProtectedInSuperClassCompanionCallChecker(),
                 UnsupportedSyntheticCallableReferenceChecker(),
                 SuperCallWithDefaultArgumentsChecker(),
-                MissingDependencyClassChecker()
+                MissingDependencyClassChecker(),
+                ProtectedSyntheticExtensionCallChecker
         ),
 
         additionalTypeCheckers = listOf(