FE: implement specific T & Any vs T! type checker mode for overrides

This commit allows type checker to consider T! <: T & Any
during type checks, and uses this mode during various overriding checks

#KT-58933 Fixed
#KT-74049 Fixed

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirImplementationMismatchChecker.kt

@@ -7,6 +7,7 @@ package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
 import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.KtRealSourceElementKind
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.impl.deduplicating
@@ -69,7 +70,8 @@ sealed class FirImplementationMismatchChecker(mppKind: MppCheckerKind) : FirClas
 
         val typeCheckerState = context.session.typeContext.newTypeCheckerState(
             errorTypesEqualToAnything = false,
-            stubTypesEqualToAnything = false
+            stubTypesEqualToAnything = false,
+            dnnTypesEqualToFlexible = context.languageVersionSettings.supportsFeature(LanguageFeature.AllowDnnTypeOverridingFlexibleType)
         )
         val classScope = declaration.unsubstitutedScope(context)
         val dedupReporter = reporter.deduplicating()

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirOverrideChecker.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.KtRealSourceElementKind
 import org.jetbrains.kotlin.KtSourceElement
 import org.jetbrains.kotlin.builtins.StandardNames
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
@@ -122,7 +123,8 @@ sealed class FirOverrideChecker(mppKind: MppCheckerKind) : FirAbstractOverrideCh
     override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         val typeCheckerState = context.session.typeContext.newTypeCheckerState(
             errorTypesEqualToAnything = false,
-            stubTypesEqualToAnything = false
+            stubTypesEqualToAnything = false,
+            dnnTypesEqualToFlexible = context.languageVersionSettings.supportsFeature(LanguageFeature.AllowDnnTypeOverridingFlexibleType)
         )
 
         val firTypeScope = declaration.unsubstitutedScope(context)

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/FirOverrideService.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
 import org.jetbrains.kotlin.fir.declarations.FirVariable
 import org.jetbrains.kotlin.fir.declarations.utils.visibility
 import org.jetbrains.kotlin.fir.resolve.transformers.ReturnTypeCalculator
+import org.jetbrains.kotlin.fir.scopes.impl.FirTypeIntersectionScopeContext.ResultOfIntersection
 import org.jetbrains.kotlin.fir.scopes.impl.buildSubstitutorForOverridesCheck
 import org.jetbrains.kotlin.fir.scopes.impl.similarFunctionsOrBothProperties
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
@@ -120,7 +121,17 @@ class FirOverrideService(val session: FirSession) : FirSessionComponent {
 
         val typeCheckerState = session.typeContext.newTypeCheckerState(
             errorTypesEqualToAnything = false,
-            stubTypesEqualToAnything = false
+            stubTypesEqualToAnything = false,
+            /**
+             * Type checking here influence only selecting of most specific members
+             * Having foo(param: T & Any) and Java foo(param: T!) and dnnTypesEqualToFlexible = true,
+             *  we can achieve 0 result here, instead of 1/-1 with dnnTypesEqualToFlexible = false.
+             * The list in [selectMostSpecificMembers] can change size because of this,
+             * and we can build [ResultOfIntersection.NonTrivial] instead of [ResultOfIntersection.SingleMember].
+             * But in fact, it does not influence resolve significantly, so it's better to keep behavior
+             * with dnnTypesEqualToFlexible = false
+             */
+            dnnTypesEqualToFlexible = false
         )
         val aSubtypesB = AbstractTypeChecker.isSubtypeOf(typeCheckerState, aReturnType, bReturnType)
         val bSubtypesA = AbstractTypeChecker.isSubtypeOf(typeCheckerState, bReturnType, aReturnType)

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

@@ -5,12 +5,14 @@
 
 package org.jetbrains.kotlin.fir.scopes.impl
 
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.declarations.utils.isSuspend
 import org.jetbrains.kotlin.fir.declarations.utils.visibility
+import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.transformers.ensureResolvedTypeDeclaration
 import org.jetbrains.kotlin.fir.symbols.impl.FirCallableSymbol
@@ -25,7 +27,10 @@ class FirStandardOverrideChecker(private val session: FirSession) : FirAbstractO
     private fun isEqualTypes(candidateType: ConeKotlinType, baseType: ConeKotlinType, substitutor: ConeSubstitutor): Boolean {
         val substitutedCandidateType = substitutor.substituteOrSelf(candidateType)
         val substitutedBaseType = substitutor.substituteOrSelf(baseType)
-        return AbstractTypeChecker.equalTypes(context, substitutedCandidateType, substitutedBaseType)
+        return AbstractTypeChecker.equalTypes(
+            context, substitutedCandidateType, substitutedBaseType,
+            dnnTypesEqualToFlexible = session.languageVersionSettings.supportsFeature(LanguageFeature.AllowDnnTypeOverridingFlexibleType)
+        )
     }
 
     fun isEqualTypes(candidateTypeRef: FirTypeRef, baseTypeRef: FirTypeRef, substitutor: ConeSubstitutor): Boolean {

compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/ConeInferenceContext.kt

@@ -131,10 +131,12 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext, ConeTypeCo
 
     override fun newTypeCheckerState(
         errorTypesEqualToAnything: Boolean,
-        stubTypesEqualToAnything: Boolean
+        stubTypesEqualToAnything: Boolean,
+        dnnTypesEqualToFlexible: Boolean,
     ): TypeCheckerState = TypeCheckerState(
         errorTypesEqualToAnything,
         stubTypesEqualToAnything,
+        dnnTypesEqualToFlexible,
         allowedTypeVariable = true,
         typeSystemContext = this,
         kotlinTypePreparator = ConeTypePreparator(session),

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeCheckerState.kt

@@ -13,6 +13,7 @@ fun createIrTypeCheckerState(typeSystemContext: IrTypeSystemContext): TypeChecke
     return TypeCheckerState(
         isErrorTypeEqualsToAnything = false,
         isStubTypeEqualsToAnything = false,
+        isDnnTypesEqualToFlexible = false,
         allowedTypeVariable = false,
         typeSystemContext = typeSystemContext,
         kotlinTypePreparator = AbstractTypePreparator.Default,

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/IrTypeSystemContext.kt

@@ -534,7 +534,8 @@ interface IrTypeSystemContext : TypeSystemContext, TypeSystemCommonSuperTypesCon
 
     override fun newTypeCheckerState(
         errorTypesEqualToAnything: Boolean,
-        stubTypesEqualToAnything: Boolean
+        stubTypesEqualToAnything: Boolean,
+        dnnTypesEqualToFlexible: Boolean,
     ): TypeCheckerState = createIrTypeCheckerState(this)
 
     override fun KotlinTypeMarker.isUninferredParameter(): Boolean = false

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

@@ -19,6 +19,7 @@ abstract class TypeCheckerStateForConstraintSystem(
 ) : TypeCheckerState(
     isErrorTypeEqualsToAnything = true,
     isStubTypeEqualsToAnything = true,
+    isDnnTypesEqualToFlexible = false,
     allowedTypeVariable = false,
     typeSystemContext = extensionTypeContext,
     kotlinTypePreparator,

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ClassicTypeSystemContextForCS.kt

@@ -99,7 +99,11 @@ class ClassicTypeSystemContextForCS(
         return isContainedInInvariantOrContravariantPositions
     }
 
-    override fun newTypeCheckerState(errorTypesEqualToAnything: Boolean, stubTypesEqualToAnything: Boolean): TypeCheckerState {
+    override fun newTypeCheckerState(
+        errorTypesEqualToAnything: Boolean,
+        stubTypesEqualToAnything: Boolean,
+        dnnTypesEqualToFlexible: Boolean,
+    ): TypeCheckerState {
         return createClassicTypeCheckerState(
             errorTypesEqualToAnything,
             stubTypesEqualToAnything,

compiler/testData/diagnostics/tests/explicitDefinitelyNotNullableViaIntersection/overridesJavaAnnotated.kt

@@ -1,5 +1,6 @@
 // RUN_PIPELINE_TILL: FRONTEND
 // FIR_IDENTICAL
+// LATEST_LV_DIFFERENCE
 // LANGUAGE: +DefinitelyNonNullableTypes +ProhibitUsingNullableTypeParameterAgainstNotNullAnnotated
 
 // FILE: A.java