K1: Deprecate incorrect callable references resolution behavior

^KT-54316 Related
^KT-54832 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -2706,6 +2706,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/callableReference/callableReferenceWithMostSpecificGenericTypeParameter.kt");
             }
 
+            @Test
+            @TestMetadata("callableReferencesToCompanionMembers.kt")
+            public void testCallableReferencesToCompanionMembers() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.kt");
+            }
+
             @Test
             @TestMetadata("classVsPackage.kt")
             public void testClassVsPackage() throws Exception {
@@ -2742,6 +2748,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.kt");
             }
 
+            @Test
+            @TestMetadata("deprecateTopLevelReferenceWithCompanionLHS.kt")
+            public void testDeprecateTopLevelReferenceWithCompanionLHS() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.kt");
+            }
+
             @Test
             @TestMetadata("deprecatedCompanionReceiverInParentheses.kt")
             public void testDeprecatedCompanionReceiverInParentheses() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -2706,6 +2706,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/callableReference/callableReferenceWithMostSpecificGenericTypeParameter.kt");
             }
 
+            @Test
+            @TestMetadata("callableReferencesToCompanionMembers.kt")
+            public void testCallableReferencesToCompanionMembers() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.kt");
+            }
+
             @Test
             @TestMetadata("classVsPackage.kt")
             public void testClassVsPackage() throws Exception {
@@ -2742,6 +2748,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.kt");
             }
 
+            @Test
+            @TestMetadata("deprecateTopLevelReferenceWithCompanionLHS.kt")
+            public void testDeprecateTopLevelReferenceWithCompanionLHS() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.kt");
+            }
+
             @Test
             @TestMetadata("deprecatedCompanionReceiverInParentheses.kt")
             public void testDeprecatedCompanionReceiverInParentheses() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -2706,6 +2706,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/callableReference/callableReferenceWithMostSpecificGenericTypeParameter.kt");
             }
 
+            @Test
+            @TestMetadata("callableReferencesToCompanionMembers.kt")
+            public void testCallableReferencesToCompanionMembers() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.kt");
+            }
+
             @Test
             @TestMetadata("classVsPackage.kt")
             public void testClassVsPackage() throws Exception {
@@ -2742,6 +2748,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.kt");
             }
 
+            @Test
+            @TestMetadata("deprecateTopLevelReferenceWithCompanionLHS.kt")
+            public void testDeprecateTopLevelReferenceWithCompanionLHS() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.kt");
+            }
+
             @Test
             @TestMetadata("deprecatedCompanionReceiverInParentheses.kt")
             public void testDeprecatedCompanionReceiverInParentheses() throws Exception {

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -889,6 +889,7 @@ public interface Errors {
     DiagnosticFactory0<KtExpression> RESERVED_SYNTAX_IN_CALLABLE_REFERENCE_LHS = DiagnosticFactory0.create(ERROR);
 
     DiagnosticFactory0<KtParenthesizedExpression> PARENTHESIZED_COMPANION_LHS_DEPRECATION = DiagnosticFactory0.create(WARNING);
+    DiagnosticFactory0<PsiElement> INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS = DiagnosticFactory0.create(WARNING);
 
     DiagnosticFactory0<PsiElement> RESOLUTION_TO_PRIVATE_CONSTRUCTOR_OF_SEALED_CLASS = DiagnosticFactory0.create(WARNING);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -460,6 +460,11 @@ public class DefaultErrorMessages {
 
         MAP.put(PARENTHESIZED_COMPANION_LHS_DEPRECATION, "Access to companion object through parenthesized class name is deprecated. Please, add explicit Companion qualifier.");
 
+        MAP.put(
+                INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS,
+                "Callable reference to the companion's member is incorrectly resolved as unbound. Please, add explicit Companion qualifier to the left-hand-side. See https://youtrack.jetbrains.com/issue/KT-54316 for details"
+        );
+
 
         MAP.put(RESOLUTION_TO_PRIVATE_CONSTRUCTOR_OF_SEALED_CLASS, "The private constructor of a sealed class will become inaccessible here in future. See https://youtrack.jetbrains.com/issue/KT-44866 for details");
         MAP.put(

compiler/frontend/src/org/jetbrains/kotlin/resolve/PlatformConfiguratorBase.kt

@@ -70,7 +70,7 @@ private val DEFAULT_CALL_CHECKERS = listOf(
     ReferencingToUnderscoreNamedParameterOfCatchBlockChecker, VarargWrongExecutionOrderChecker, SelfCallInNestedObjectConstructorChecker,
     NewSchemeOfIntegerOperatorResolutionChecker, EnumEntryVsCompanionPriorityCallChecker, CompanionInParenthesesLHSCallChecker,
     ResolutionToPrivateConstructorOfSealedClassChecker, EqualityCallChecker, UnsupportedUntilOperatorChecker,
-    BuilderInferenceAssignmentChecker, IncorrectCapturedApproximationCallChecker,
+    BuilderInferenceAssignmentChecker, IncorrectCapturedApproximationCallChecker, CompanionIncorrectlyUnboundedWhenUsedAsLHSCallChecker,
 )
 private val DEFAULT_TYPE_CHECKERS = emptyList<AdditionalTypeChecker>()
 private val DEFAULT_CLASSIFIER_USAGE_CHECKERS = listOf(

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/checkers/CompanionLHSRelatedCheckers.kt

@@ -13,8 +13,11 @@ import org.jetbrains.kotlin.psi.KtDotQualifiedExpression
 import org.jetbrains.kotlin.psi.KtParenthesizedExpression
 import org.jetbrains.kotlin.psi.KtReferenceExpression
 import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.calls.context.CallPosition
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall
+import org.jetbrains.kotlin.resolve.scopes.receivers.ClassQualifier
 import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver
+import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
 
 /**
  * Deprecate callable references in a form of (SomeClass)::name when SomeClass has a companion
@@ -27,16 +30,49 @@ object CompanionInParenthesesLHSCallChecker : CallChecker {
         val unwrappedLhs = parenthesizedExpression.expression ?: return
         val expressionReceiver = resolvedCall.call.explicitReceiver as? ExpressionReceiver ?: return
 
-        val referencedClass = expressionReceiver.type.constructor.declarationDescriptor as? ClassDescriptor ?: return
+        if (!isReferenceToShortFormCompanion(expressionReceiver, unwrappedLhs, context)) return
-        if (!referencedClass.isCompanionObject) return
-
-        // We should also consider cases like (package.MyClassWithCompanion)::foo
-        val simpleReference =
-            ((unwrappedLhs as? KtDotQualifiedExpression)?.selectorExpression ?: unwrappedLhs) as? KtReferenceExpression
-                ?: return
-
-        if (context.trace.bindingContext[BindingContext.SHORT_REFERENCE_TO_COMPANION_OBJECT, simpleReference] == null) return
 
         context.trace.report(Errors.PARENTHESIZED_COMPANION_LHS_DEPRECATION.on(parenthesizedExpression))
     }
 }
+
+/**
+ * Report warnings on top-level callable references (one that are not nested in any call) that have short-formed LHS resolved to companion
+ * Because they have wrong function type shape at K1
+ * (see relevant testData)
+ */
+object CompanionIncorrectlyUnboundedWhenUsedAsLHSCallChecker : CallChecker {
+    override fun check(resolvedCall: ResolvedCall<*>, reportOn: PsiElement, context: CallCheckerContext) {
+        val callableReference = resolvedCall.call.callElement.parent as? KtCallableReferenceExpression ?: return
+        val classQualifier = resolvedCall.call.explicitReceiver as? ClassQualifier ?: return
+        val dispatchReceiver = resolvedCall.dispatchReceiver ?: return
+
+        if (dispatchReceiver != classQualifier.classValueReceiver) return
+
+        // Only top-level callable references may have callPosition like this
+        // References nested in calls have CallPosition.Unknown
+        if (context.resolutionContext.callPosition !is CallPosition.CallableReferenceRhs) return
+
+        val referencedClass = dispatchReceiver.type.constructor.declarationDescriptor as? ClassDescriptor ?: return
+        if (!referencedClass.isCompanionObject) return
+
+        context.trace.report(Errors.INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS.on(callableReference))
+    }
+
+}
+
+private fun isReferenceToShortFormCompanion(
+    receiver: ReceiverValue,
+    lhs: PsiElement?,
+    context: CallCheckerContext
+): Boolean {
+    val referencedClass = receiver.type.constructor.declarationDescriptor as? ClassDescriptor ?: return false
+    if (!referencedClass.isCompanionObject) return false
+
+    // We should also consider cases like (package.MyClassWithCompanion)::foo
+    val simpleReference =
+        ((lhs as? KtDotQualifiedExpression)?.selectorExpression ?: lhs) as? KtReferenceExpression
+            ?: return false
+
+    return context.trace.bindingContext[BindingContext.SHORT_REFERENCE_TO_COMPANION_OBJECT, simpleReference] != null
+}

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

@@ -37,5 +37,5 @@ fun test() {
     val r7 = c::foo
     checkSubtype<() -> String>(r7)
 
-    C::bar
+    <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>C::bar<!>
 }

compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.fir.kt

@@ -0,0 +1,13 @@
+// FIR_DUMP
+
+class Foo {
+    companion object {
+        fun bar() {}
+        val baz = 42
+    }
+}
+
+val x1 = Foo::bar
+val x2 = Foo.Companion::bar
+val x3 = Foo::baz
+val x4 = Foo.Companion::baz

compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.fir.txt

@@ -0,0 +1,28 @@
+FILE: callableReferencesToCompanionMembers.fir.kt
+    public final class Foo : R|kotlin/Any| {
+        public constructor(): R|Foo| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final companion object Companion : R|kotlin/Any| {
+            private constructor(): R|Foo.Companion| {
+                super<R|kotlin/Any|>()
+            }
+
+            public final fun bar(): R|kotlin/Unit| {
+            }
+
+            public final val baz: R|kotlin/Int| = Int(42)
+                public get(): R|kotlin/Int|
+
+        }
+
+    }
+    public final val x1: R|kotlin/reflect/KFunction0<kotlin/Unit>| = Q|Foo|::R|/Foo.Companion.bar|
+        public get(): R|kotlin/reflect/KFunction0<kotlin/Unit>|
+    public final val x2: R|kotlin/reflect/KFunction0<kotlin/Unit>| = Q|Foo.Companion|::R|/Foo.Companion.bar|
+        public get(): R|kotlin/reflect/KFunction0<kotlin/Unit>|
+    public final val x3: R|kotlin/reflect/KProperty0<kotlin/Int>| = Q|Foo|::R|/Foo.Companion.baz|
+        public get(): R|kotlin/reflect/KProperty0<kotlin/Int>|
+    public final val x4: R|kotlin/reflect/KProperty0<kotlin/Int>| = Q|Foo.Companion|::R|/Foo.Companion.baz|
+        public get(): R|kotlin/reflect/KProperty0<kotlin/Int>|

compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.kt

@@ -0,0 +1,13 @@
+// FIR_DUMP
+
+class Foo {
+    companion object {
+        fun bar() {}
+        val baz = 42
+    }
+}
+
+val x1 = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>Foo::bar<!>
+val x2 = Foo.Companion::bar
+val x3 = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>Foo::baz<!>
+val x4 = Foo.Companion::baz

compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.txt

@@ -0,0 +1,22 @@
+package
+
+public val x1: kotlin.reflect.KFunction1<Foo, kotlin.Unit>
+public val x2: kotlin.reflect.KFunction0<kotlin.Unit>
+public val x3: kotlin.reflect.KProperty1<Foo, kotlin.Int>
+public val x4: kotlin.reflect.KProperty0<kotlin.Int>
+
+public final class Foo {
+    public constructor Foo()
+    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 companion object Companion {
+        private constructor Companion()
+        public final val baz: kotlin.Int = 42
+        public final fun bar(): 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
+    }
+}

compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.fir.kt

@@ -0,0 +1,79 @@
+// SKIP_TXT
+
+class A {
+    companion object {
+        fun foo(): Int = 43
+        val companionProp: Int = 44
+    }
+
+    fun baz(): Int = 1
+    val memberProp: Int = 2
+}
+
+object Obj {
+    fun foo(): Int = 43
+    val objProp: Int = 44
+}
+
+fun main() {
+    A::foo.invoke(<!TOO_MANY_ARGUMENTS!>A()<!>)
+    A::foo.invoke()
+    val x = A::foo
+    x.invoke(<!TOO_MANY_ARGUMENTS!>A()<!>)
+    x.invoke()
+
+    A.Companion::foo.invoke()
+    val x0 = A.Companion::foo
+    x0.invoke()
+
+    bar(A::foo)
+
+    val y = id(A::foo)
+    y.invoke()
+
+    A::baz.invoke(A())
+
+    val z = A::baz
+    z.invoke(A())
+    bam(A::baz)
+
+    Obj::foo.invoke()
+
+    val zObj = Obj::foo
+    zObj.invoke()
+    bar(Obj::foo)
+}
+
+fun mainProp() {
+    A::companionProp.invoke(<!TOO_MANY_ARGUMENTS!>A()<!>)
+    A::companionProp.invoke()
+    val x = A::companionProp
+    x.invoke(<!TOO_MANY_ARGUMENTS!>A()<!>)
+    x.invoke()
+
+    A.Companion::companionProp.invoke()
+    val x0 = A.Companion::companionProp
+    x0.invoke()
+
+    bar(A::companionProp)
+
+    val y = id(A::companionProp)
+    y.invoke()
+
+    A::memberProp.invoke(A())
+
+    val z = A::memberProp
+    z.invoke(A())
+    bam(A::memberProp)
+
+    Obj::objProp.invoke()
+
+    val zObj = Obj::objProp
+    zObj.invoke()
+    bar(Obj::objProp)
+}
+
+fun <E> id(e: E): E = e
+
+fun bar(x: () -> Int) {}
+fun bam(x: A.() -> Int) {}

compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.kt

@@ -0,0 +1,79 @@
+// SKIP_TXT
+
+class A {
+    companion object {
+        fun foo(): Int = 43
+        val companionProp: Int = 44
+    }
+
+    fun baz(): Int = 1
+    val memberProp: Int = 2
+}
+
+object Obj {
+    fun foo(): Int = 43
+    val objProp: Int = 44
+}
+
+fun main() {
+    <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::foo<!>.invoke(A())
+    <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::foo<!>.invoke<!NO_VALUE_FOR_PARAMETER!>()<!>
+    val x = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::foo<!>
+    x.invoke(A())
+    x.invoke<!NO_VALUE_FOR_PARAMETER!>()<!>
+
+    A.Companion::foo.invoke()
+    val x0 = A.Companion::foo
+    x0.invoke()
+
+    bar(A::foo)
+
+    val y = id(A::foo)
+    y.invoke()
+
+    A::baz.invoke(A())
+
+    val z = A::baz
+    z.invoke(A())
+    bam(A::baz)
+
+    Obj::foo.invoke()
+
+    val zObj = Obj::foo
+    zObj.invoke()
+    bar(Obj::foo)
+}
+
+fun mainProp() {
+    <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::companionProp<!>.invoke(A())
+    <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::companionProp<!>.invoke<!NO_VALUE_FOR_PARAMETER!>()<!>
+    val x = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>A::companionProp<!>
+    x.invoke(A())
+    x.invoke<!NO_VALUE_FOR_PARAMETER!>()<!>
+
+    A.Companion::companionProp.invoke()
+    val x0 = A.Companion::companionProp
+    x0.invoke()
+
+    bar(A::companionProp)
+
+    val y = id(A::companionProp)
+    y.invoke()
+
+    A::memberProp.invoke(A())
+
+    val z = A::memberProp
+    z.invoke(A())
+    bam(A::memberProp)
+
+    Obj::objProp.invoke()
+
+    val zObj = Obj::objProp
+    zObj.invoke()
+    bar(Obj::objProp)
+}
+
+fun <E> id(e: E): E = e
+
+fun bar(x: () -> Int) {}
+fun bam(x: A.() -> Int) {}

compiler/testData/diagnostics/tests/callableReference/withQuestionMarks.kt

@@ -26,6 +26,6 @@ fun main() {
     // It must be OK
     val x18 = String?::hashCode <!USELESS_ELVIS!>?: ::foo<!>
     val x19 = String::hashCode <!USELESS_ELVIS!>?: ::foo<!>
-    val x20 = String?::hashCode::hashCode
+    val x20 = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>String?::hashCode<!>::hashCode
-    val x21 = kotlin.String?::hashCode::hashCode
+    val x21 = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>kotlin.String?::hashCode<!>::hashCode
 }

compiler/testData/diagnostics/tests/objects/kt21515/callableReferenceComplexCasesWithImportsOld.fir.kt

@@ -0,0 +1,74 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+import A.Base.Companion.FromABaseCompanion
+import B.Base.Companion.FromBBaseCompanion
+import C.Base.Companion.FromCBaseCompanion
+import D.Base.Companion.FromDBaseCompanion
+
+// ===== Case 1: LHS is a class
+//
+object A {
+    open class Base {
+        companion object {
+            class FromABaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromABaseCompanion::foo
+    }
+}
+
+// ===== Case 2: LHS is a class with companion object, function comes from class
+
+object B {
+    open class Base {
+        companion object {
+            class FromBBaseCompanion {
+                fun foo() = 42
+
+                companion object {}
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromBBaseCompanion::foo
+    }
+}
+
+// ==== Case 3: LHS is a class with companion object, function comes from companion
+
+object C {
+    open class Base {
+        companion object {
+            class FromCBaseCompanion {
+                companion object {
+                    fun foo() = 42
+                }
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromCBaseCompanion::foo
+    }
+}
+
+// ==== Case 4: LHS is an object
+
+object D {
+    open class Base {
+        companion object {
+            object FromDBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = FromDBaseCompanion::foo
+    }
+}

compiler/testData/diagnostics/tests/objects/kt21515/callableReferenceComplexCasesWithImportsOld.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
 
 import A.Base.Companion.FromABaseCompanion
@@ -54,7 +53,7 @@ object C {
     }
 
     class Derived : Base() {
-        val a = FromCBaseCompanion::foo
+        val a = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>FromCBaseCompanion::foo<!>
     }
 }
 

compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesComplexCasesWithQualificationOld.fir.kt

@@ -0,0 +1,69 @@
+// !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
+
+// ===== Case 1: LHS is a class
+//
+object A {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = A.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ===== Case 2: LHS is a class with companion object, function comes from class
+
+object B {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                fun foo() = 42
+
+                companion object {}
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = B.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 3: LHS is a class with companion object, function comes from companion
+
+object C {
+    open class Base {
+        companion object {
+            class FromBaseCompanion {
+                companion object {
+                    fun foo() = 42
+                }
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = C.Base.Companion.FromBaseCompanion::foo
+    }
+}
+
+// ==== Case 4: LHS is an object
+
+object D {
+    open class Base {
+        companion object {
+            object FromBaseCompanion {
+                fun foo() = 42
+            }
+        }
+    }
+
+    class Derived : Base() {
+        val a = D.Base.Companion.FromBaseCompanion::foo
+    }
+}

compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesComplexCasesWithQualificationOld.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ProhibitVisibilityOfNestedClassifiersFromSupertypesOfCompanion
 
 // ===== Case 1: LHS is a class
@@ -49,7 +48,7 @@ object C {
     }
 
     class Derived : Base() {
-        val a = C.Base.Companion.FromBaseCompanion::foo
+        val a = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!>C.Base.Companion.FromBaseCompanion::foo<!>
     }
 }
 

compiler/testData/diagnostics/tests/objects/kt21515/callableReferencesOldComplexCases.kt

@@ -48,7 +48,7 @@ object C {
     }
 
     class Derived : Base() {
-        val a = <!DEPRECATED_ACCESS_BY_SHORT_NAME!>FromBaseCompanion<!>::foo
+        val a = <!INCORRECT_CALLABLE_REFERENCE_RESOLUTION_FOR_COMPANION_LHS!><!DEPRECATED_ACCESS_BY_SHORT_NAME!>FromBaseCompanion<!>::foo<!>
     }
 }
 

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -2712,6 +2712,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/callableReference/callableReferenceWithMostSpecificGenericTypeParameter.kt");
             }
 
+            @Test
+            @TestMetadata("callableReferencesToCompanionMembers.kt")
+            public void testCallableReferencesToCompanionMembers() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/callableReferencesToCompanionMembers.kt");
+            }
+
             @Test
             @TestMetadata("classVsPackage.kt")
             public void testClassVsPackage() throws Exception {
@@ -2748,6 +2754,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/callableReference/correctInfoAfterArrayLikeCall.kt");
             }
 
+            @Test
+            @TestMetadata("deprecateTopLevelReferenceWithCompanionLHS.kt")
+            public void testDeprecateTopLevelReferenceWithCompanionLHS() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/callableReference/deprecateTopLevelReferenceWithCompanionLHS.kt");
+            }
+
             @Test
             @TestMetadata("deprecatedCompanionReceiverInParentheses.kt")
             public void testDeprecatedCompanionReceiverInParentheses() throws Exception {