[FIR] Treat properties from ObjC-classes as abstract

In short, the problem is some
platform libraries contain invalid
Kotlin code. Specifically,
some classes may inherit multiple
members with default
implementations, but do not define
an explicit override, like `UIView.bounds`.

Since we can't refactor platrofm
libraries just now, we want to
treat such properties as abstract.

^KT-65866 Fixed
^KT-65855

compiler/fir/native/src/org/jetbrains/kotlin/fir/backend/native/FirNativeOverrideChecker.kt

@@ -5,16 +5,20 @@
 
 package org.jetbrains.kotlin.fir.backend.native
 
+import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.backend.native.interop.decodeObjCMethodAnnotation
-import org.jetbrains.kotlin.fir.declarations.FirCallableDeclaration
+import org.jetbrains.kotlin.fir.backend.native.interop.isObjCClass
-import org.jetbrains.kotlin.fir.declarations.FirProperty
+import org.jetbrains.kotlin.fir.containingClassLookupTag
-import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
+import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.scopes.FirOverrideChecker
 import org.jetbrains.kotlin.fir.scopes.MemberWithBaseScope
-import org.jetbrains.kotlin.fir.scopes.impl.FirStandardOverrideChecker
+import org.jetbrains.kotlin.fir.scopes.impl.*
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 
 /**
@@ -37,7 +41,14 @@ class FirNativeOverrideChecker(private val session: FirSession) : FirOverrideChe
     override fun <D : FirCallableSymbol<*>> chooseIntersectionVisibility(
         extractedOverrides: Collection<MemberWithBaseScope<D>>,
         dispatchClassSymbol: FirRegularClassSymbol?,
-    ): Visibility = standardOverrideChecker.chooseIntersectionVisibility(extractedOverrides, dispatchClassSymbol)
+    ): Visibility {
+        val nonSubsumed = extractedOverrides.getNonSubsumedNonPhantomOverriddenSymbols()
+        return chooseIntersectionVisibilityOrNull(nonSubsumed) { it.isAbstract || it.member.isObjCClassProperty(session) }
+            ?: Visibilities.Unknown
+    }
+
+    private fun FirCallableSymbol<*>.isObjCClassProperty(session: FirSession) =
+        this is FirPropertySymbol && (containingClassLookupTag()?.toSymbol(session) as? FirClassSymbol<*>)?.isObjCClass(session) ?: false
 
     /**
      * mimics ObjCOverridabilityCondition.isOverridable

compiler/fir/native/src/org/jetbrains/kotlin/fir/backend/native/interop/FirObjCInterop.kt

@@ -109,7 +109,7 @@ internal fun FirConstructorSymbol.isObjCConstructor(session: FirSession) =
 /**
  * mimics IrClass.isObjCClass()
  */
-private fun FirClassSymbol<*>.isObjCClass(session: FirSession) = classId.packageFqName != NativeStandardInteropNames.cInteropPackage &&
+fun FirClassSymbol<*>.isObjCClass(session: FirSession) = classId.packageFqName != NativeStandardInteropNames.cInteropPackage &&
         selfOrAnySuperClass(session) {
             it.classId == NativeStandardInteropNames.objCObjectClassId
         }

compiler/fir/providers/src/org/jetbrains/kotlin/fir/declarations/declarationUtils.kt

@@ -160,9 +160,15 @@ fun MemberWithBaseScope<FirCallableSymbol<*>>.getNonSubsumedOverriddenSymbols():
         .map { it.member }
 }
 
-fun List<MemberWithBaseScope<FirCallableSymbol<*>>>.getNonSubsumedNonPhantomOverriddenSymbols(): List<MemberWithBaseScope<FirCallableSymbol<*>>> {
+fun Collection<MemberWithBaseScope<FirCallableSymbol<*>>>.getNonSubsumedNonPhantomOverriddenSymbols(): List<MemberWithBaseScope<FirCallableSymbol<*>>> {
+    // It's crucial that we only unwrap phantom intersection overrides.
+    // See comments in the following tests for explanation:
+    // - intersectionWithMultipleDefaultsInJavaOverriddenByIntersectionInKotlin.kt
+    // - intersectionOverridesIntersection.kt
     return flatMap { it.flattenPhantomIntersectionsRecursively() }
         .nonSubsumed()
+        // To learn why `distinctBy` is needed, see:
+        // - intersectionWithMultipleDefaultsInJavaWithAdditionalSymbolsAfterNonSubsumed.kt
         .distinctBy { it.member.unwrapSubstitutionOverrides<FirCallableSymbol<*>>() }
 }
 

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirOverrideUtils.kt

@@ -64,12 +64,13 @@ fun <D : FirCallableSymbol<*>> overrides(
     return result
 }
 
-fun chooseIntersectionVisibilityOrNull(
+inline fun chooseIntersectionVisibilityOrNull(
     nonSubsumedOverrides: List<MemberWithBaseScope<FirCallableSymbol<*>>>,
+    isAbstract: (MemberWithBaseScope<FirCallableSymbol<*>>) -> Boolean = MemberWithBaseScope<FirCallableSymbol<*>>::isAbstract,
 ): Visibility? {
     val nonAbstract = nonSubsumedOverrides.filter {
         // Kotlin's Cloneable interface contains phantom `protected open fun clone()`.
-        !it.isAbstract && it.member.callableId != StandardClassIds.Callables.clone
+        !isAbstract(it) && it.member.callableId != StandardClassIds.Callables.clone
     }
     val allAreAbstract = nonAbstract.isEmpty()