Fix type of member references without explicit class on LHS

Type of '::foo' for a function foo in a class A should be KFunction0<Unit>, not
KFunction1<A, Unit>. Continue to report an error in this case, to be maybe
supported in the future

compiler/frontend/src/org/jetbrains/kotlin/resolve/callableReferences/CallableReferencesResolutionUtils.kt

@@ -181,24 +181,6 @@ fun resolveCallableReferenceTarget(
     }
 }
 
-private fun createReflectionTypeForFunction(
-        descriptor: FunctionDescriptor,
-        receiverType: KotlinType?,
-        reflectionTypes: ReflectionTypes
-): KotlinType? {
-    val returnType = descriptor.returnType ?: return null
-    val valueParametersTypes = ExpressionTypingUtils.getValueParametersTypes(descriptor.valueParameters)
-    return reflectionTypes.getKFunctionType(Annotations.EMPTY, receiverType, valueParametersTypes, returnType)
-}
-
-private fun createReflectionTypeForProperty(
-        descriptor: PropertyDescriptor,
-        receiverType: KotlinType?,
-        reflectionTypes: ReflectionTypes
-): KotlinType {
-    return reflectionTypes.getKPropertyType(Annotations.EMPTY, receiverType, descriptor.type, descriptor.isVar)
-}
-
 private fun bindFunctionReference(expression: KtCallableReferenceExpression, type: KotlinType, context: ResolutionContext<*>) {
     val functionDescriptor = AnonymousFunctionDescriptor(
             context.scope.ownerDescriptor,
@@ -230,7 +212,8 @@ private fun createReflectionTypeForCallableDescriptor(
         lhsType: KotlinType?,
         reflectionTypes: ReflectionTypes,
         trace: BindingTrace?,
-        reportOn: KtExpression?
+        reportOn: KtExpression?,
+        ignoreReceiver: Boolean
 ): KotlinType? {
     val extensionReceiver = descriptor.extensionReceiverParameter
     val dispatchReceiver = descriptor.dispatchReceiverParameter?.let { dispatchReceiver ->
@@ -248,15 +231,19 @@ private fun createReflectionTypeForCallableDescriptor(
     }
 
     val receiverType =
-            if (extensionReceiver != null || dispatchReceiver != null)
+            if ((extensionReceiver != null || dispatchReceiver != null) && !ignoreReceiver)
                 lhsType ?: extensionReceiver?.type ?: dispatchReceiver?.type
             else null
 
     return when (descriptor) {
-        is FunctionDescriptor ->
+        is FunctionDescriptor -> {
-            createReflectionTypeForFunction(descriptor, receiverType, reflectionTypes)
+            val returnType = descriptor.returnType ?: return null
-        is PropertyDescriptor ->
+            val valueParametersTypes = ExpressionTypingUtils.getValueParametersTypes(descriptor.valueParameters)
-            createReflectionTypeForProperty(descriptor, receiverType, reflectionTypes)
+            return reflectionTypes.getKFunctionType(Annotations.EMPTY, receiverType, valueParametersTypes, returnType)
+        }
+        is PropertyDescriptor -> {
+            reflectionTypes.getKPropertyType(Annotations.EMPTY, receiverType, descriptor.type, descriptor.isVar)
+        }
         is VariableDescriptor -> {
             if (reportOn != null) {
                 trace?.report(UNSUPPORTED.on(reportOn, "References to variables aren't supported yet"))
@@ -270,9 +257,10 @@ private fun createReflectionTypeForCallableDescriptor(
 
 fun getReflectionTypeForCandidateDescriptor(
         descriptor: CallableDescriptor,
-        reflectionTypes: ReflectionTypes
+        reflectionTypes: ReflectionTypes,
+        ignoreReceiver: Boolean
 ): KotlinType? =
-        createReflectionTypeForCallableDescriptor(descriptor, null, reflectionTypes, null, null)
+        createReflectionTypeForCallableDescriptor(descriptor, null, reflectionTypes, null, null, ignoreReceiver)
 
 fun createReflectionTypeForResolvedCallableReference(
         reference: KtCallableReferenceExpression,
@@ -282,7 +270,7 @@ fun createReflectionTypeForResolvedCallableReference(
         reflectionTypes: ReflectionTypes
 ): KotlinType? {
     val type = createReflectionTypeForCallableDescriptor(
-            descriptor, lhsType, reflectionTypes, context.trace, reference.getCallableReference()
+            descriptor, lhsType, reflectionTypes, context.trace, reference.callableReference, reference.typeReference == null
     ) ?: return null
     when (descriptor) {
         is FunctionDescriptor -> {
@@ -310,7 +298,8 @@ fun getResolvedCallableReferenceShapeType(
                 null
             overloadResolutionResults.isSingleResult ->
                 OverloadResolutionResultsUtil.getResultingCall(overloadResolutionResults, context.contextDependency)?.let { call ->
-                    createReflectionTypeForCallableDescriptor(call.resultingDescriptor, lhsType, reflectionTypes, context.trace, reference)
+                    createReflectionTypeForCallableDescriptor(call.resultingDescriptor, lhsType, reflectionTypes, context.trace, reference,
+                                                              reference.typeReference == null)
                 }
             expectedTypeUnknown /* && overload resolution was ambiguous */ ->
                 functionPlaceholders.createFunctionPlaceholderType(emptyList(), false)

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CandidateResolver.kt

@@ -157,8 +157,11 @@ class CandidateResolver(
     private fun <D : CallableDescriptor, F : D> CallCandidateResolutionContext<D>.checkExpectedCallableType()
             = check {
                 if (!noExpectedType(expectedType)) {
-                    val candidate = candidateCall.getCandidateDescriptor()
+                    val candidate = candidateCall.candidateDescriptor
-                    val candidateReflectionType = getReflectionTypeForCandidateDescriptor(candidate, reflectionTypes);
+                    val candidateReflectionType = getReflectionTypeForCandidateDescriptor(
+                            candidate, reflectionTypes,
+                            call.callElement.parent.let { it is KtCallableReferenceExpression && it.typeReference == null }
+                    );
                     if (candidateReflectionType != null) {
                         if (!KotlinTypeChecker.DEFAULT.isSubtypeOf(candidateReflectionType, expectedType)) {
                             candidateCall.addStatus(OTHER_ERROR)

compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.kt

@@ -1,6 +1,9 @@
 // !CHECK_TYPE
 
-import kotlin.reflect.KFunction1
+import kotlin.reflect.KFunction0
+
+fun explicitlyExpectFunction0(f: () -> Unit) = f
+fun explicitlyExpectFunction1(f: (A) -> Unit) = f
 
 fun foo() {}
 
@@ -10,6 +13,12 @@ class A {
     fun main() {
         val x = ::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>foo<!>
 
-        checkSubtype<KFunction1<A, Unit>>(x)
+        checkSubtype<KFunction0<Unit>>(x)
+
+        explicitlyExpectFunction0(x)
+        explicitlyExpectFunction1(<!TYPE_MISMATCH!>x<!>)
+
+        explicitlyExpectFunction0(::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>foo<!>)
+        explicitlyExpectFunction1(<!TYPE_MISMATCH!>::<!CALLABLE_REFERENCE_TO_MEMBER_OR_EXTENSION_WITH_EMPTY_LHS!>foo<!><!>)
     }
 }

compiler/testData/diagnostics/tests/callableReference/function/noAmbiguityMemberVsTopLevel.txt

@@ -1,5 +1,7 @@
 package
 
+public fun explicitlyExpectFunction0(/*0*/ f: () -> kotlin.Unit): () -> kotlin.Unit
+public fun explicitlyExpectFunction1(/*0*/ f: (A) -> kotlin.Unit): (A) -> kotlin.Unit
 public fun foo(): kotlin.Unit
 
 public final class A {

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/smart/Utils.kt

@@ -248,7 +248,9 @@ private fun MutableCollection<LookupElement>.addLookupElementsForNullable(factor
 
 fun CallableDescriptor.callableReferenceType(resolutionFacade: ResolutionFacade): FuzzyType? {
     if (!CallType.CALLABLE_REFERENCE.descriptorKindFilter.accepts(this)) return null // not supported by callable references
-    return getReflectionTypeForCandidateDescriptor(this, resolutionFacade.getFrontendService(ReflectionTypes::class.java))?.toFuzzyType(emptyList())
+    return getReflectionTypeForCandidateDescriptor(
+            this, resolutionFacade.getFrontendService(ReflectionTypes::class.java), false
+    )?.toFuzzyType(emptyList())
 }
 
 enum class SmartCompletionItemPriority {