Fix resolution of candidates with empty intersections

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirReceiverAccessBeforeSuperCallChecker.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.fir.analysis.checkers.expression
 
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.reportOn
-import org.jetbrains.kotlin.fir.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.fir.analysis.checkers.MppCheckerKind
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
@@ -17,6 +16,7 @@ import org.jetbrains.kotlin.fir.expressions.FirQualifiedAccessExpression
 import org.jetbrains.kotlin.fir.expressions.InaccessibleReceiverKind
 import org.jetbrains.kotlin.fir.expressions.arguments
 import org.jetbrains.kotlin.fir.render
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 @OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
 object FirReceiverAccessBeforeSuperCallChecker : FirInaccessibleReceiverChecker(MppCheckerKind.Common) {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ArgumentUtils.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.fir.resolve.calls
 
 import org.jetbrains.kotlin.fir.FirSession
-import org.jetbrains.kotlin.fir.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.fir.collectUpperBounds
 import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.FirExpression
@@ -25,6 +24,7 @@ import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilder
 import org.jetbrains.kotlin.resolve.calls.inference.components.ResultTypeResolver
 import org.jetbrains.kotlin.resolve.calls.inference.components.TypeVariableDirectionCalculator.ResolveDirection.UNKNOWN
 import org.jetbrains.kotlin.types.model.TypeSystemCommonSuperTypesContext
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.utils.addToStdlib.applyIf
 import kotlin.contracts.ExperimentalContracts
 import kotlin.contracts.contract

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/FirCallResolver.kt

@@ -59,6 +59,7 @@ import org.jetbrains.kotlin.resolve.calls.tower.CandidateApplicability
 import org.jetbrains.kotlin.resolve.calls.tower.isSuccess
 import org.jetbrains.kotlin.resolve.calls.tower.shouldStopResolve
 import org.jetbrains.kotlin.types.Variance
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 import org.jetbrains.kotlin.utils.addToStdlib.shouldNotBeCalled

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/candidate/CandidateCollector.kt

@@ -15,6 +15,7 @@ import org.jetbrains.kotlin.resolve.calls.tower.ApplicabilityDetail
 import org.jetbrains.kotlin.resolve.calls.tower.CandidateApplicability
 import org.jetbrains.kotlin.resolve.calls.tower.isSuccess
 import org.jetbrains.kotlin.resolve.calls.tower.shouldStopResolve
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 open class CandidateCollector(
     val components: BodyResolveComponents,
@@ -65,6 +66,7 @@ open class CandidateCollector(
                 dropOldCandidates()
             }
 
+            @OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
             if (currentApplicability == CandidateApplicability.RESOLVED_NEED_PRESERVE_COMPATIBILITY &&
                 applicability > currentApplicability
             ) {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/overloads/FirOverloadByLambdaReturnTypeResolver.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.fir.resolve.calls.overloads
 
 import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.fir.FirAnnotationContainer
-import org.jetbrains.kotlin.fir.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.expressions.FirResolvable
 import org.jetbrains.kotlin.fir.resolve.calls.CandidateChosenUsingOverloadResolutionByLambdaAnnotation
@@ -26,6 +25,7 @@ import org.jetbrains.kotlin.fir.types.isSomeFunctionType
 import org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintSystemCompletionMode
 import org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintSystemCompletionMode.ExclusiveForOverloadResolutionByLambdaReturnType
 import org.jetbrains.kotlin.resolve.descriptorUtil.OVERLOAD_RESOLUTION_BY_LAMBDA_ANNOTATION_CLASS_ID
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.utils.addToStdlib.same
 
 /**

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/stages/CreateFreshTypeVariableSubstitutorStage.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.fir.resolve.calls.stages
 
 import org.jetbrains.kotlin.config.LanguageFeature
-import org.jetbrains.kotlin.fir.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.expressions.ExplicitTypeArgumentIfMadeFlexibleSyntheticallyTypeAttribute
 import org.jetbrains.kotlin.fir.isEnabled
@@ -37,6 +36,7 @@ import org.jetbrains.kotlin.fir.unwrapSubstitutionOverrides
 import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemOperation
 import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystemConstraintPosition
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 internal object CreateFreshTypeVariableSubstitutorStage : ResolutionStage() {
     context(sink: CheckerSink, context: ResolutionContext)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/stages/ResolutionStages.kt

@@ -54,6 +54,7 @@ import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
 import org.jetbrains.kotlin.types.model.TypeVariableTypeConstructorMarker
 import org.jetbrains.kotlin.types.model.typeConstructor
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 import org.jetbrains.kotlin.utils.addToStdlib.unreachableBranch
 
@@ -843,6 +844,7 @@ private fun Candidate.isJavaApplicableCandidate(): Boolean {
 }
 
 internal object EagerResolveOfCallableReferences : ResolutionStage() {
+    @OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
     context(sink: CheckerSink, context: ResolutionContext)
     override suspend fun check(candidate: Candidate) {
         if (candidate.postponedAtoms.isEmpty()) return
@@ -863,6 +865,8 @@ internal object EagerResolveOfCallableReferences : ResolutionStage() {
                 } else when (applicability) {
                     CandidateApplicability.RESOLVED_NEED_PRESERVE_COMPATIBILITY ->
                         sink.reportDiagnostic(LowerPriorityToPreserveCompatibilityDiagnostic)
+                    CandidateApplicability.RESOLVED_LOW_PRIORITY ->
+                        sink.reportDiagnostic(ResolvedWithLowPriority)
                     else -> {
                     }
                 }
@@ -980,9 +984,6 @@ internal object CheckIncompatibleTypeVariableUpperBounds : ResolutionStage() {
                         emptyIntersectionTypeInfo.casingTypes.toList() as List<ConeKotlinType>,
                         variableWithConstraints.typeVariable.asCone(),
                         emptyIntersectionTypeInfo.kind,
-                        isError = context.session.languageVersionSettings.supportsFeature(
-                            LanguageFeature.ForbidInferringTypeVariablesIntoEmptyIntersection
-                        )
                     )
                 )
             }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/BodyResolveContext.kt

@@ -38,6 +38,7 @@ import org.jetbrains.kotlin.fir.types.classId
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.SpecialNames.UNDERSCORE_FOR_UNUSED_VAR
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.util.PrivateForInline
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirDeclarationsResolveTransformer.kt

@@ -61,6 +61,7 @@ import org.jetbrains.kotlin.resolve.calls.inference.buildCurrentSubstitutor
 import org.jetbrains.kotlin.resolve.calls.inference.components.TypeVariableDirectionCalculator
 import org.jetbrains.kotlin.resolve.calls.inference.model.ProvideDelegateFixationPosition
 import org.jetbrains.kotlin.types.model.TypeConstructorMarker
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.util.PrivateForInline
 import org.jetbrains.kotlin.utils.addToStdlib.runIf

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt

@@ -62,6 +62,7 @@ import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.types.ConstantValueKind
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
 import org.jetbrains.kotlin.types.model.anySuperTypeConstructor
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.util.PrivateForInline
 import org.jetbrains.kotlin.utils.addToStdlib.applyIf

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/calls/ResolutionDiagnostic.kt

@@ -6,13 +6,17 @@
 package org.jetbrains.kotlin.fir.resolve.calls
 
 import org.jetbrains.kotlin.KtSourceElement
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.fir.SessionHolder
 import org.jetbrains.kotlin.fir.declarations.FirAnonymousFunction
 import org.jetbrains.kotlin.fir.declarations.FirFunction
 import org.jetbrains.kotlin.fir.declarations.FirTypeParameter
 import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.fir.expressions.FirNamedArgumentExpression
 import org.jetbrains.kotlin.fir.expressions.FirSmartCastExpression
+import org.jetbrains.kotlin.fir.isEnabled
+import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirConstructorSymbol
@@ -23,12 +27,14 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirValueParameterSymbol
 import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.ConeTypeVariable
 import org.jetbrains.kotlin.resolve.ForbiddenNamedArgumentsTarget
+import org.jetbrains.kotlin.resolve.calls.inference.isError
 import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintSystemError
 import org.jetbrains.kotlin.resolve.calls.tower.ApplicabilityDetail
 import org.jetbrains.kotlin.resolve.calls.tower.CandidateApplicability
 import org.jetbrains.kotlin.resolve.calls.tower.CandidateApplicability.*
 import org.jetbrains.kotlin.resolve.calls.tower.isSuccess
 import org.jetbrains.kotlin.types.EmptyIntersectionTypeKind
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 abstract class ResolutionDiagnostic(val applicability: CandidateApplicability)
 
@@ -38,13 +44,36 @@ abstract class InapplicableArgumentDiagnostic : ResolutionDiagnostic(INAPPLICABL
 
 class MixingNamedAndPositionArguments(override val argument: FirExpression) : InapplicableArgumentDiagnostic()
 
-class InferredEmptyIntersectionDiagnostic(
+class InferredEmptyIntersectionDiagnostic private constructor(
     val incompatibleTypes: Collection<ConeKotlinType>,
     val causingTypes: Collection<ConeKotlinType>,
     val typeVariable: ConeTypeVariable,
     val kind: EmptyIntersectionTypeKind,
-    val isError: Boolean
-) : ResolutionDiagnostic(INAPPLICABLE)
+    val isError: Boolean,
+    applicability: CandidateApplicability,
+) : ResolutionDiagnostic(applicability) {
+    companion object {
+        context(sessionHolder: SessionHolder)
+        operator fun invoke(
+            incompatibleTypes: Collection<ConeKotlinType>,
+            causingTypes: Collection<ConeKotlinType>,
+            typeVariable: ConeTypeVariable,
+            kind: EmptyIntersectionTypeKind,
+        ): InferredEmptyIntersectionDiagnostic {
+            val isError = kind.isError(sessionHolder.session.languageVersionSettings)
+            val isInapplicable = isError || !LanguageFeature.FixApplicabilityOfEmptyIntersection.isEnabled()
+
+            return InferredEmptyIntersectionDiagnostic(
+                incompatibleTypes,
+                causingTypes,
+                typeVariable,
+                kind,
+                isError,
+                if (isInapplicable) INAPPLICABLE else RESOLVED_LOW_PRIORITY
+            )
+        }
+    }
+}
 
 class TooManyArguments(
     val argument: FirExpression,
@@ -141,6 +170,7 @@ object InvokeOnHiddenCompanionObject : ResolutionDiagnostic(HIDDEN)
 
 class InapplicableNullableReceiver(val actualType: ConeKotlinType) : ResolutionDiagnostic(UNSAFE_CALL)
 
+@OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
 object LowerPriorityToPreserveCompatibilityDiagnostic : ResolutionDiagnostic(RESOLVED_NEED_PRESERVE_COMPATIBILITY)
 
 object LowerPriorityForDynamic : ResolutionDiagnostic(RESOLVED_LOW_PRIORITY)

compiler/fir/tree/src/org/jetbrains/kotlin/fir/annotations.kt

@@ -38,15 +38,6 @@ annotation class PrivateSessionConstructor
 @RequiresOptIn
 annotation class SessionConfiguration
 
-/**
- * Declarations that are only being used in case some default language features are disabled: mostly likely due to using not the latest
- * language version.
- *
- * Let's try to have a convention to use a relevant language feature name as a side comment.
- */
-@RequiresOptIn
-annotation class OnlyForDefaultLanguageFeatureDisabled(val languageFeature: LanguageFeature)
-
 /**
  * Declaration is only relevant for old (pre-CL) resolution of array literals for annotations.
  */

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/InaccessibleReceiverKind.kt

@@ -6,7 +6,7 @@
 package org.jetbrains.kotlin.fir.expressions
 
 import org.jetbrains.kotlin.config.LanguageFeature
-import org.jetbrains.kotlin.fir.OnlyForDefaultLanguageFeatureDisabled
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 /**
  * Enum describing the different kinds of [FirInaccessibleReceiverExpression].
@@ -59,4 +59,4 @@ enum class InaccessibleReceiverKind(
      * ```
      */
     ClassHeader(false),
-}
+}

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/inference/InferenceUtils.kt

@@ -5,9 +5,12 @@
 
 package org.jetbrains.kotlin.resolve.calls.inference
 
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.resolve.calls.inference.components.extractProjectionsForAllCapturedTypes
 import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
 import org.jetbrains.kotlin.resolve.calls.inference.model.NewConstraintSystemImpl
+import org.jetbrains.kotlin.types.EmptyIntersectionTypeKind
 import org.jetbrains.kotlin.types.model.*
 
 fun ConstraintStorage.buildCurrentSubstitutor(
@@ -111,3 +114,7 @@ private fun KotlinTypeMarker.extractAllContainingTypeVariablesNoCaptureTypeProce
         false
     }
 }
+
+fun EmptyIntersectionTypeKind.isError(settings: LanguageVersionSettings): Boolean {
+    return isDefinitelyEmpty && settings.supportsFeature(LanguageFeature.ForbidInferringTypeVariablesIntoEmptyIntersection)
+}

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/inference/model/ConstraintPositionAndErrors.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.types.EmptyIntersectionTypeKind
 import org.jetbrains.kotlin.types.model.KotlinTypeMarker
 import org.jetbrains.kotlin.types.model.TypeParameterMarker
 import org.jetbrains.kotlin.types.model.TypeVariableMarker
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 
 interface OnlyInputTypeConstraintPosition
 
@@ -180,6 +181,7 @@ class InferredEmptyIntersectionError(
 
 class OnlyInputTypesDiagnostic(val typeVariable: TypeVariableMarker) : ConstraintSystemError(INAPPLICABLE)
 
+@OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
 class LowerPriorityToPreserveCompatibility(val needToReportWarning: Boolean) :
     ConstraintSystemError(RESOLVED_NEED_PRESERVE_COMPATIBILITY)
 

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/inference/model/NewConstraintSystemImpl.kt

@@ -734,9 +734,7 @@ class NewConstraintSystemImpl(
         // Remove existing errors from the resolution stage because a completion stage error is always more precise
         storage.errors.removeIf { it is InferredEmptyIntersection }
 
-        val isInferredEmptyIntersectionForbidden =
-            languageVersionSettings.supportsFeature(LanguageFeature.ForbidInferringTypeVariablesIntoEmptyIntersection)
-        val errorFactory = if (emptyIntersectionTypeInfo.kind.isDefinitelyEmpty && isInferredEmptyIntersectionForbidden)
+        val errorFactory = if (emptyIntersectionTypeInfo.kind.isError(languageVersionSettings))
             ::InferredEmptyIntersectionError
         else ::InferredEmptyIntersectionWarning
 

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/tower/CandidateApplicability.kt

@@ -5,6 +5,9 @@
 
 package org.jetbrains.kotlin.resolve.calls.tower
 
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
+
 enum class CandidateApplicability {
     /**
      * Special applicability for migration warning up to 1.5.
@@ -98,6 +101,7 @@ enum class CandidateApplicability {
      * Candidate is successful but uses new features that change resolve.
      * Tower resolve proceeds to next levels.
      */
+    @OnlyForDefaultLanguageFeatureDisabled(LanguageFeature.DisableCompatibilityModeForNewInference, LanguageFeature.DisableCompatibilityModeForNewInference)
     RESOLVED_NEED_PRESERVE_COMPATIBILITY,
 
     // Everything below has shouldStopResolve = true

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/tower/TowerResolver.kt

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValueWithSmartCastI
 import org.jetbrains.kotlin.resolve.scopes.utils.parentsWithSelf
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.isDynamic
+import org.jetbrains.kotlin.util.OnlyForDefaultLanguageFeatureDisabled
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import java.util.*
 
@@ -466,6 +467,7 @@ class TowerResolver {
             return candidate.resultingApplicability.shouldStopResolve
         }
 
+        @OptIn(OnlyForDefaultLanguageFeatureDisabled::class)
         private fun isPreserveCompatibilityCandidate(candidate: C): Boolean =
             candidate.resultingApplicability == CandidateApplicability.RESOLVED_NEED_PRESERVE_COMPATIBILITY
 

compiler/testData/diagnostics/tests/collectionLiterals/multipleOverloads/callableReferenceInCLSamConverted.kt

@@ -1,3 +1,4 @@
+// LATEST_LV_DIFFERENCE
 // RUN_PIPELINE_TILL: FRONTEND
 // LANGUAGE: +CollectionLiterals, +CompanionBlocksAndExtensions
 // WITH_STDLIB