Fix incorrect unsupported error on synthetic extension call on LHS of ::

#KT-13271 Fixed

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

@@ -18,8 +18,7 @@ package org.jetbrains.kotlin.resolve.jvm.checkers
 
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.diagnostics.Errors.UNSUPPORTED
-import org.jetbrains.kotlin.psi.KtCallableReferenceExpression
-import org.jetbrains.kotlin.psi.KtNameReferenceExpression
+import org.jetbrains.kotlin.resolve.calls.callUtil.isCallableReference
 import org.jetbrains.kotlin.resolve.calls.checkers.CallChecker
 import org.jetbrains.kotlin.resolve.calls.checkers.CallCheckerContext
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
@@ -27,11 +26,8 @@ import org.jetbrains.kotlin.synthetic.SyntheticJavaPropertyDescriptor
 
 class UnsupportedSyntheticCallableReferenceChecker : CallChecker {
     override fun check(resolvedCall: ResolvedCall<*>, reportOn: PsiElement, context: CallCheckerContext) {
-        val expression = resolvedCall.call.callElement
-        if (expression !is KtNameReferenceExpression || expression.parent !is KtCallableReferenceExpression) return
-
         // TODO: support references to synthetic Java extension properties (KT-8575)
-        if (resolvedCall.resultingDescriptor is SyntheticJavaPropertyDescriptor) {
+        if (resolvedCall.call.isCallableReference() && resolvedCall.resultingDescriptor is SyntheticJavaPropertyDescriptor) {
             context.trace.report(UNSUPPORTED.on(reportOn, "reference to the synthetic extension property for a Java get/set method"))
         }
     }

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

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.resolve.BindingContext.CONSTRAINT_SYSTEM_COMPLETER
 import org.jetbrains.kotlin.resolve.calls.callResolverUtil.ResolveArgumentsMode.RESOLVE_FUNCTION_ARGUMENTS
 import org.jetbrains.kotlin.resolve.calls.callResolverUtil.getEffectiveExpectedType
 import org.jetbrains.kotlin.resolve.calls.callResolverUtil.isInvokeCallOnVariable
+import org.jetbrains.kotlin.resolve.calls.callUtil.isCallableReference
 import org.jetbrains.kotlin.resolve.calls.callUtil.isFakeElement
 import org.jetbrains.kotlin.resolve.calls.checkers.CallChecker
 import org.jetbrains.kotlin.resolve.calls.checkers.CallCheckerContext
@@ -175,7 +176,7 @@ class CallCompleter(
         val returnType = candidateDescriptor.returnType
 
         val expectedReturnType =
-                if (isResolvingCallableReference(call)) {
+                if (call.isCallableReference()) {
                     // TODO: compute generic type argument for R in the kotlin.Function<R> supertype (KT-12963)
                     // TODO: also add constraints for parameter types (KT-12964)
                     if (!TypeUtils.noExpectedType(expectedType) && expectedType.isFunctionType) getReturnTypeFromFunctionType(expectedType)
@@ -241,11 +242,6 @@ class CallCompleter(
         setResultingSubstitutor(system.resultingSubstitutor)
     }
 
-    private fun isResolvingCallableReference(call: Call): Boolean {
-        val callElement = call.callElement
-        return (callElement.parent as? KtCallableReferenceExpression)?.callableReference == callElement
-    }
-
     private fun <D : CallableDescriptor> MutableResolvedCall<D>.updateResolutionStatusFromConstraintSystem(
             context: BasicCallResolutionContext,
             tracing: TracingStrategy

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/util/callUtil.kt

@@ -229,6 +229,12 @@ fun Call.isSafeCall(): Boolean {
 
 fun Call.isExplicitSafeCall(): Boolean = callOperationNode?.elementType == KtTokens.SAFE_ACCESS
 
+fun Call.isCallableReference(): Boolean {
+    val callElement = callElement
+    return callElement is KtNameReferenceExpression &&
+           (callElement.parent as? KtCallableReferenceExpression)?.callableReference == callElement
+}
+
 fun Call.createLookupLocation(): KotlinLookupLocation {
     val calleeExpression = calleeExpression
     val element =

compiler/testData/codegen/box/callableReference/bound/syntheticExtensionOnLHS.kt

@@ -0,0 +1,21 @@
+// WITH_RUNTIME
+// FILE: A.java
+
+public class A {
+    private final String field;
+
+    public A(String field) {
+        this.field = field;
+    }
+
+    public CharSequence getFoo() { return field; }
+}
+
+// FILE: test.kt
+
+fun box(): String {
+    with (A("OK")) {
+        val k = foo::toString
+        return k()
+    }
+}

compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.kt

@@ -0,0 +1,13 @@
+// FILE: A.java
+
+class A {
+    public CharSequence getFoo() { return null; }
+}
+
+// FILE: test.kt
+
+fun test() {
+    with (A()) {
+        foo::toString
+    }
+}

compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.txt

@@ -0,0 +1,11 @@
+package
+
+public fun test(): kotlin.Unit
+
+public/*package*/ open class A {
+    public/*package*/ constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun getFoo(): kotlin.CharSequence!
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -1811,6 +1811,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("syntheticExtensionOnLHS.kt")
+                public void testSyntheticExtensionOnLHS() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/callableReference/bound/syntheticExtensionOnLHS.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("valueOfTypeParameterType.kt")
                 public void testValueOfTypeParameterType() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/callableReference/bound/valueOfTypeParameterType.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -1500,6 +1500,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("syntheticExtensionOnLHS.kt")
+            public void testSyntheticExtensionOnLHS() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/callableReference/bound/syntheticExtensionOnLHS.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("compiler/testData/codegen/box/callableReference/bound/inline")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)