Fix type of reference to protected var

#KT-12982 Fixed

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/DoubleColonExpressionResolver.kt

@@ -527,8 +527,7 @@ class DoubleColonExpressionResolver(
                 is PropertyDescriptor -> {
                     val mutable = descriptor.isVar && run {
                         val setter = descriptor.setter
-                        // TODO: support private-to-this
-                        setter == null || Visibilities.isVisible(null, setter, scopeOwnerDescriptor)
+                        setter == null || Visibilities.isVisible(receiverType?.let(::TransientReceiver), setter, scopeOwnerDescriptor)
                     }
                     reflectionTypes.getKPropertyType(Annotations.EMPTY, receiverType, descriptor.type, mutable)
                 }

compiler/testData/codegen/box/callableReference/property/kt12982_protectedPropertyReference.kt

@@ -0,0 +1,12 @@
+class Foo {
+    protected var x = 0
+
+    fun getX() = Foo::x
+}
+
+fun box(): String {
+    val x = Foo().getX()
+    val foo = Foo()
+    x.set(foo, 42)
+    return if (x.get(foo) == 42) "OK" else "Fail"
+}

compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.kt

@@ -0,0 +1,22 @@
+// KT-12982 Incorrect type inference when accessing mutable protected property via reflection
+
+import kotlin.reflect.KMutableProperty1
+
+class Foo {
+    protected var x = 0
+
+    fun baz(p: KMutableProperty1<Foo, Int>) = p
+    fun print() = baz(Foo::x)
+}
+
+
+open class A {
+    protected fun a() {}
+}
+
+open class B : A() {
+    val x = C::a
+    val y = C()::a
+}
+
+class C : B()

compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.txt

@@ -0,0 +1,39 @@
+package
+
+public open class A {
+    public constructor A()
+    protected final fun a(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public open class B : A {
+    public constructor B()
+    public final val x: kotlin.reflect.KFunction1<C, kotlin.Unit>
+    public final val y: kotlin.reflect.KFunction0<kotlin.Unit>
+    protected final override /*1*/ /*fake_override*/ fun a(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class C : B {
+    public constructor C()
+    public final override /*1*/ /*fake_override*/ val x: kotlin.reflect.KFunction1<C, kotlin.Unit>
+    public final override /*1*/ /*fake_override*/ val y: kotlin.reflect.KFunction0<kotlin.Unit>
+    protected final override /*1*/ /*fake_override*/ fun a(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Foo {
+    public constructor Foo()
+    protected final var x: kotlin.Int
+    public final fun baz(/*0*/ p: kotlin.reflect.KMutableProperty1<Foo, kotlin.Int>): kotlin.reflect.KMutableProperty1<Foo, kotlin.Int>
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final fun print(): kotlin.reflect.KMutableProperty1<Foo, kotlin.Int>
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

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

@@ -2204,6 +2204,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("protectedVarFromClass.kt")
+                public void testProtectedVarFromClass() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/callableReference/property/protectedVarFromClass.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("returnTypeDependentOnGenericProperty.kt")
                 public void testReturnTypeDependentOnGenericProperty() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/callableReference/property/returnTypeDependentOnGenericProperty.kt");

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

@@ -1950,6 +1950,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt12982_protectedPropertyReference.kt")
+            public void testKt12982_protectedPropertyReference() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/callableReference/property/kt12982_protectedPropertyReference.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("kt6870_privatePropertyReference.kt")
             public void testKt6870_privatePropertyReference() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/callableReference/property/kt6870_privatePropertyReference.kt");