FIR: use frontend-independent Java type qualifier computation

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/EnhancementSignatureParts.kt

@@ -1,148 +0,0 @@
-/*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.fir.java.enhancement
-
-import org.jetbrains.kotlin.builtins.jvm.JavaToKotlinClassMap
-import org.jetbrains.kotlin.fir.FirAnnotationContainer
-import org.jetbrains.kotlin.fir.FirSession
-import org.jetbrains.kotlin.fir.declarations.FirValueParameter
-import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
-import org.jetbrains.kotlin.fir.java.FirJavaTypeConversionMode
-import org.jetbrains.kotlin.fir.java.JavaTypeParameterStack
-import org.jetbrains.kotlin.fir.java.toConeKotlinTypeProbablyFlexible
-import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
-import org.jetbrains.kotlin.fir.types.*
-import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
-import org.jetbrains.kotlin.fir.types.jvm.FirJavaTypeRef
-import org.jetbrains.kotlin.load.java.AnnotationQualifierApplicabilityType
-import org.jetbrains.kotlin.load.java.JavaDefaultQualifiers
-import org.jetbrains.kotlin.load.java.typeEnhancement.*
-import org.jetbrains.kotlin.name.FqNameUnsafe
-import org.jetbrains.kotlin.utils.addToStdlib.safeAs
-
-internal class EnhancementSignatureParts(
-    private val typeQualifierResolver: FirAnnotationTypeQualifierResolver,
-    private val typeContainer: FirAnnotationContainer?,
-    private val javaTypeParameterStack: JavaTypeParameterStack,
-    private val current: FirJavaTypeRef,
-    private val fromOverridden: Collection<FirTypeRef>,
-    private val isCovariant: Boolean,
-    private val context: FirJavaEnhancementContext,
-    private val containerApplicabilityType: AnnotationQualifierApplicabilityType
-) {
-    private val isForVarargParameter get() = typeContainer.safeAs<FirValueParameter>()?.isVararg == true
-
-    private fun ConeKotlinType.toFqNameUnsafe(): FqNameUnsafe? =
-        ((this as? ConeLookupTagBasedType)?.lookupTag as? ConeClassLikeLookupTag)?.classId?.asSingleFqName()?.toUnsafe()
-
-    internal fun enhance(
-        session: FirSession,
-        predefined: TypeEnhancementInfo? = null,
-        forAnnotationMember: Boolean = false
-    ): FirResolvedTypeRef {
-        val mode = if (forAnnotationMember) FirJavaTypeConversionMode.ANNOTATION_MEMBER else FirJavaTypeConversionMode.DEFAULT
-        val typeWithoutEnhancement = current.toConeKotlinTypeProbablyFlexible(session, javaTypeParameterStack, mode)
-        val qualifiers = computeIndexedQualifiersForOverride(typeWithoutEnhancement, predefined)
-        return buildResolvedTypeRef {
-            type = typeWithoutEnhancement.enhance(session, qualifiers) ?: typeWithoutEnhancement
-            annotations += current.annotations
-        }
-    }
-
-    private fun ConeKotlinType?.toIndexed(context: FirJavaEnhancementContext): List<TypeAndDefaultQualifiers> {
-        val list = ArrayList<TypeAndDefaultQualifiers>(1)
-
-        fun add(type: ConeKotlinType?) {
-            // TODO: should use the context from parent type
-            val annotations = type?.attributes?.customAnnotations.orEmpty()
-            val c = context.copyWithNewDefaultTypeQualifiers(typeQualifierResolver, annotations)
-            list.add(TypeAndDefaultQualifiers(type, c.defaultTypeQualifiers?.get(AnnotationQualifierApplicabilityType.TYPE_USE)))
-            type?.typeArguments?.forEach { add(it.type) }
-        }
-
-        add(this)
-        return list
-    }
-
-    private fun ConeKotlinType.extractQualifiers(): JavaTypeQualifiers {
-        val lower = lowerBoundIfFlexible()
-        val upper = upperBoundIfFlexible()
-        val mapping = JavaToKotlinClassMap
-        return JavaTypeQualifiers(
-            when {
-                lower.isMarkedNullable -> NullabilityQualifier.NULLABLE
-                !upper.isMarkedNullable -> NullabilityQualifier.NOT_NULL
-                else -> null
-            },
-            when {
-                mapping.isReadOnly(lower.toFqNameUnsafe()) -> MutabilityQualifier.READ_ONLY
-                mapping.isMutable(upper.toFqNameUnsafe()) -> MutabilityQualifier.MUTABLE
-                else -> null
-            },
-            isNotNullTypeParameter = lower is ConeDefinitelyNotNullType
-        )
-    }
-
-    private fun composeAnnotations(first: List<FirAnnotationCall>, second: List<FirAnnotationCall>): List<FirAnnotationCall> {
-        return when {
-            first.isEmpty() -> second
-            second.isEmpty() -> first
-            else -> first + second
-        }
-    }
-
-    private fun TypeAndDefaultQualifiers.extractQualifiersFromAnnotations(isHeadTypeConstructor: Boolean): JavaTypeQualifiers {
-        val annotations = type?.attributes?.customAnnotations.orEmpty()
-        val composedAnnotations =
-            if (isHeadTypeConstructor && typeContainer != null)
-                composeAnnotations(typeContainer.annotations, annotations)
-            else
-                annotations
-
-        val defaultTypeQualifier =
-            if (isHeadTypeConstructor)
-                context.defaultTypeQualifiers?.get(containerApplicabilityType)
-            else
-                defaultQualifiers
-
-        val nullabilityInfo = typeQualifierResolver.extractNullability(composedAnnotations)
-            ?: defaultTypeQualifier?.nullabilityQualifier
-
-        return JavaTypeQualifiers(
-            nullabilityInfo?.qualifier,
-            typeQualifierResolver.extractMutability(composedAnnotations),
-            isNotNullTypeParameter = nullabilityInfo?.qualifier == NullabilityQualifier.NOT_NULL &&
-                    type?.lowerBoundIfFlexible() is ConeTypeParameterType,
-            isNullabilityQualifierForWarning = nullabilityInfo?.isForWarningOnly == true
-        )
-    }
-
-    private fun computeIndexedQualifiersForOverride(current: ConeKotlinType?, predefined: TypeEnhancementInfo?): IndexedJavaTypeQualifiers {
-        val indexedFromSupertypes =
-            fromOverridden.map { it.toConeKotlinTypeProbablyFlexible(context.session, javaTypeParameterStack).toIndexed(context) }
-        val indexedThisType = current.toIndexed(context)
-
-        // The covariant case may be hard, e.g. in the superclass the return may be Super<T>, but in the subclass it may be Derived, which
-        // is declared to extend Super<T>, and propagating data here is highly non-trivial, so we only look at the head type constructor
-        // (outermost type), unless the type in the subclass is interchangeable with the all the types in superclasses:
-        // e.g. we have (Mutable)List<String!>! in the subclass and { List<String!>, (Mutable)List<String>! } from superclasses
-        // Note that `this` is flexible here, so it's equal to it's bounds
-        val onlyHeadTypeConstructor = isCovariant && fromOverridden.any { true /*equalTypes(it, this)*/ }
-
-        val treeSize = if (onlyHeadTypeConstructor) 1 else indexedThisType.size
-        val computedResult = Array(treeSize) { index ->
-            val qualifiers = indexedThisType[index].extractQualifiersFromAnnotations(index == 0)
-            val superQualifiers = indexedFromSupertypes.mapNotNull { it.getOrNull(index)?.type?.extractQualifiers() }
-            qualifiers.computeQualifiersForOverride(superQualifiers, index == 0 && isCovariant, index == 0 && isForVarargParameter)
-        }
-        return { index -> predefined?.map?.get(index) ?: computedResult.getOrNull(index) ?: JavaTypeQualifiers.NONE }
-    }
-
-    private data class TypeAndDefaultQualifiers(
-        val type: ConeKotlinType?, // null denotes '*' here
-        val defaultQualifiers: JavaDefaultQualifiers?
-    )
-}

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/SignatureEnhancement.kt

@@ -21,13 +21,17 @@ import org.jetbrains.kotlin.fir.declarations.utils.isInner
 import org.jetbrains.kotlin.fir.declarations.utils.isStatic
 import org.jetbrains.kotlin.fir.declarations.utils.modality
 import org.jetbrains.kotlin.fir.declarations.utils.visibility
+import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
+import org.jetbrains.kotlin.fir.java.FirJavaTypeConversionMode
 import org.jetbrains.kotlin.fir.java.JavaTypeParameterStack
 import org.jetbrains.kotlin.fir.java.declarations.*
 import org.jetbrains.kotlin.fir.java.toConeKotlinTypeProbablyFlexible
 import org.jetbrains.kotlin.fir.scopes.jvm.computeJvmDescriptor
+import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
+import org.jetbrains.kotlin.fir.symbols.ConeTypeParameterLookupTag
 import org.jetbrains.kotlin.fir.symbols.impl.*
-import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
-import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.jvm.FirJavaTypeRef
 import org.jetbrains.kotlin.load.java.AnnotationQualifierApplicabilityType
 import org.jetbrains.kotlin.load.java.typeEnhancement.*
@@ -35,6 +39,12 @@ import org.jetbrains.kotlin.load.kotlin.SignatureBuildingComponents
 import org.jetbrains.kotlin.name.CallableId
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.load.java.JavaTypeEnhancementState
+import org.jetbrains.kotlin.load.java.JavaTypeQualifiersByElementType
+import org.jetbrains.kotlin.name.FqNameUnsafe
+import org.jetbrains.kotlin.types.AbstractTypeChecker
+import org.jetbrains.kotlin.types.model.KotlinTypeMarker
+import org.jetbrains.kotlin.types.model.TypeParameterMarker
+import org.jetbrains.kotlin.types.model.TypeSystemContext
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 class FirSignatureEnhancement(
@@ -170,7 +180,7 @@ class FirSignatureEnhancement(
         }
         return enhanceMethod(firMethod, original.callableId, name)
     }
-    
+
     private fun enhanceMethod(
         firMethod: FirFunction,
         methodId: CallableId,
@@ -309,14 +319,16 @@ class FirSignatureEnhancement(
         overriddenMembers: List<FirCallableDeclaration>,
         memberContext: FirJavaEnhancementContext
     ): FirResolvedTypeRef {
-        return ownerFunction.partsForValueParameter(
+        return ownerFunction.enhanceValueParameter(
             typeQualifierResolver,
             overriddenMembers,
             // TODO: check me
             parameterContainer = ownerFunction,
             methodContext = memberContext,
-            typeInSignature = TypeInSignature.Receiver
-        ).enhance(session)
+            typeInSignature = TypeInSignature.Receiver,
+            predefined = null,
+            forAnnotationMember = false
+        )
     }
 
     private fun enhanceValueParameterType(
@@ -331,15 +343,13 @@ class FirSignatureEnhancement(
         if (ownerParameter.returnTypeRef is FirResolvedTypeRef) {
             return ownerParameter.returnTypeRef as FirResolvedTypeRef
         }
-        return ownerFunction.partsForValueParameter(
+        return ownerFunction.enhanceValueParameter(
             typeQualifierResolver,
             overriddenMembers,
             parameterContainer = ownerParameter,
             methodContext = memberContext,
-            typeInSignature = TypeInSignature.ValueParameter(hasReceiver, index)
-        ).enhance(
-            session,
-            predefinedEnhancementInfo?.parametersInfo?.getOrNull(index),
+            typeInSignature = TypeInSignature.ValueParameter(hasReceiver, index),
+            predefined = predefinedEnhancementInfo?.parametersInfo?.getOrNull(index),
             forAnnotationMember = owner.classKind == ClassKind.ANNOTATION_CLASS
         )
     }
@@ -350,7 +360,7 @@ class FirSignatureEnhancement(
         memberContext: FirJavaEnhancementContext,
         predefinedEnhancementInfo: PredefinedFunctionEnhancementInfo?
     ): FirResolvedTypeRef {
-        return owner.parts(
+        return owner.enhance(
             typeQualifierResolver,
             overriddenMembers,
             typeContainer = owner, isCovariant = true,
@@ -358,9 +368,9 @@ class FirSignatureEnhancement(
             containerApplicabilityType =
             if (owner is FirJavaField) AnnotationQualifierApplicabilityType.FIELD
             else AnnotationQualifierApplicabilityType.METHOD_RETURN_TYPE,
-            typeInSignature = TypeInSignature.Return
-        ).enhance(
-            session, predefinedEnhancementInfo?.returnTypeInfo, forAnnotationMember = this.owner.classKind == ClassKind.ANNOTATION_CLASS
+            typeInSignature = TypeInSignature.Return,
+            predefined = predefinedEnhancementInfo?.returnTypeInfo,
+            forAnnotationMember = this.owner.classKind == ClassKind.ANNOTATION_CLASS
         )
     }
 
@@ -388,14 +398,16 @@ class FirSignatureEnhancement(
         }
     }
 
-    private fun FirFunction.partsForValueParameter(
+    private fun FirFunction.enhanceValueParameter(
         typeQualifierResolver: FirAnnotationTypeQualifierResolver,
         overriddenMembers: List<FirCallableDeclaration>,
         // TODO: investigate if it's really can be a null (check properties' with extension overrides in Java)
         parameterContainer: FirAnnotationContainer?,
         methodContext: FirJavaEnhancementContext,
-        typeInSignature: TypeInSignature
-    ): EnhancementSignatureParts = (this as FirCallableDeclaration).parts(
+        typeInSignature: TypeInSignature,
+        predefined: TypeEnhancementInfo?,
+        forAnnotationMember: Boolean
+    ): FirResolvedTypeRef = (this as FirCallableDeclaration).enhance(
         typeQualifierResolver,
         overriddenMembers,
         parameterContainer, false,
@@ -403,33 +415,79 @@ class FirSignatureEnhancement(
             methodContext.copyWithNewDefaultTypeQualifiers(typeQualifierResolver, it.annotations)
         } ?: methodContext,
         AnnotationQualifierApplicabilityType.VALUE_PARAMETER,
-        typeInSignature
+        typeInSignature,
+        predefined,
+        forAnnotationMember
     )
 
-    private fun FirCallableDeclaration.parts(
+    private fun FirCallableDeclaration.enhance(
         typeQualifierResolver: FirAnnotationTypeQualifierResolver,
         overriddenMembers: List<FirCallableDeclaration>,
         typeContainer: FirAnnotationContainer?,
         isCovariant: Boolean,
         containerContext: FirJavaEnhancementContext,
         containerApplicabilityType: AnnotationQualifierApplicabilityType,
-        typeInSignature: TypeInSignature
-    ): EnhancementSignatureParts {
-        val typeRef = typeInSignature.getTypeRef(this)
-        return EnhancementSignatureParts(
-            typeQualifierResolver,
-            typeContainer,
-            javaTypeParameterStack,
-            typeRef as FirJavaTypeRef,
-            overriddenMembers.map {
-                typeInSignature.getTypeRef(it)
-            },
-            isCovariant,
-            // recompute default type qualifiers using type annotations
-            containerContext.copyWithNewDefaultTypeQualifiers(
-                typeQualifierResolver, typeRef.annotations
-            ),
-            containerApplicabilityType
+        typeInSignature: TypeInSignature,
+        predefined: TypeEnhancementInfo?,
+        forAnnotationMember: Boolean
+    ): FirResolvedTypeRef {
+        val parts = EnhancementSignatureParts(
+            session, typeQualifierResolver, typeContainer, isCovariant,
+            containerApplicabilityType, containerContext.defaultTypeQualifiers
         )
+        val typeRef = typeInSignature.getTypeRef(this)
+        val mode = if (forAnnotationMember) FirJavaTypeConversionMode.ANNOTATION_MEMBER else FirJavaTypeConversionMode.DEFAULT
+        val typeWithoutEnhancement = typeRef.toConeKotlinType(mode)
+        val typesFromOverridden = overriddenMembers.map { typeInSignature.getTypeRef(it).toConeKotlinType(mode) }
+        val qualifiers = with(parts) { typeWithoutEnhancement.computeIndexedQualifiers(typesFromOverridden, predefined) }
+        return buildResolvedTypeRef {
+            type = typeWithoutEnhancement.enhance(session, qualifiers) ?: typeWithoutEnhancement
+            annotations += typeRef.annotations
+        }
     }
+
+    private fun FirTypeRef.toConeKotlinType(mode: FirJavaTypeConversionMode): ConeKotlinType =
+        toConeKotlinTypeProbablyFlexible(session, javaTypeParameterStack, mode)
+}
+
+private class EnhancementSignatureParts(
+    private val session: FirSession,
+    override val annotationTypeQualifierResolver: FirAnnotationTypeQualifierResolver,
+    private val typeContainer: FirAnnotationContainer?,
+    override val isCovariant: Boolean,
+    override val containerApplicabilityType: AnnotationQualifierApplicabilityType,
+    override val containerDefaultTypeQualifiers: JavaTypeQualifiersByElementType?
+) : AbstractSignatureParts<FirAnnotationCall>() {
+    override val enableImprovementsInStrictMode: Boolean
+        get() = true
+
+    override val skipRawTypeArguments: Boolean
+        get() = false
+
+    override val containerAnnotations: Iterable<FirAnnotationCall>
+        get() = typeContainer?.annotations ?: emptyList()
+
+    override val containerIsVarargParameter: Boolean
+        get() = typeContainer is FirValueParameter && typeContainer.isVararg
+
+    override val typeSystem: TypeSystemContext
+        get() = session.typeContext
+
+    override val FirAnnotationCall.forceWarning: Boolean
+        get() = false // TODO: force warnings on IDEA external annotations
+
+    override val KotlinTypeMarker.annotations: Iterable<FirAnnotationCall>
+        get() = (this as ConeKotlinType).attributes.customAnnotations
+
+    override val KotlinTypeMarker.fqNameUnsafe: FqNameUnsafe?
+        get() = ((this as? ConeLookupTagBasedType)?.lookupTag as? ConeClassLikeLookupTag)?.classId?.asSingleFqName()?.toUnsafe()
+
+    override val KotlinTypeMarker.enhancedForWarnings: KotlinTypeMarker?
+        get() = null // TODO: implement enhancement for warnings
+
+    override fun KotlinTypeMarker.isEqual(other: KotlinTypeMarker): Boolean =
+        AbstractTypeChecker.equalTypes(session.typeContext, this, other)
+
+    override val TypeParameterMarker.isFromJava: Boolean
+        get() = (this as ConeTypeParameterLookupTag).symbol.fir.origin == FirDeclarationOrigin.Java
 }

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/javaTypeUtils.kt

@@ -34,8 +34,6 @@ import org.jetbrains.kotlin.types.AbstractStrictEqualityTypeChecker
 import org.jetbrains.kotlin.types.ConstantValueKind
 import org.jetbrains.kotlin.utils.extractRadix
 
-typealias IndexedJavaTypeQualifiers = (Int) -> JavaTypeQualifiers
-
 internal fun ConeKotlinType.enhance(session: FirSession, qualifiers: IndexedJavaTypeQualifiers): ConeKotlinType? =
     enhanceConeKotlinType(session, qualifiers, 0, mutableListOf<Int>().apply { computeSubtreeSizes(this) })
 

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/strictMode/NullnessUnspecifiedTypeParameter.fir.kt

@@ -15,23 +15,19 @@ public class Test {}
 
 // FILE: main.kt
 fun main(a1: NullnessUnspecifiedTypeParameter<Any>, a2: NullnessUnspecifiedTypeParameter<Any?>, x: Test): Unit {
-    // jspecify_nullness_mismatch
-    a1.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a1.foo(null)
     a1.foo(1)
 
-    // jspecify_nullness_mismatch
-    a2.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a2.foo(null)
     a2.foo(1)
 
-    // jspecify_nullness_mismatch, jspecify_nullness_mismatch
-    a1.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, <!NULL_FOR_NONNULL_TYPE!>null<!>)
     // jspecify_nullness_mismatch
-    a1.bar(x, <!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a1.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, null)
+    a1.bar(x, null)
     a1.bar(x, 1)
 
-    // jspecify_nullness_mismatch, jspecify_nullness_mismatch
-    a2.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, <!NULL_FOR_NONNULL_TYPE!>null<!>)
     // jspecify_nullness_mismatch
-    a2.bar(x, <!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a2.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, null)
+    a2.bar(x, null)
     a2.bar(x, 1)
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/strictMode/SelfType.fir.kt

@@ -39,15 +39,12 @@ public class CKN extends C<@Nullable CK> {}
 // FILE: main.kt
 fun main(ak: AK, akn: AKN, bk: BK, ck: CK, ckn: CKN): Unit {
     ak.foo(ak)
-    // jspecify_nullness_mismatch
-    ak.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    ak.foo(null)
 
-    // jspecify_nullness_mismatch
-    akn.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    akn.foo(null)
 
     bk.foo(bk)
-    // jspecify_nullness_mismatch
-    bk.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    bk.foo(null)
 
     ck.foo(ck)
     ck.foo(null)

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/strictMode/TypeParameterBounds.fir.kt

@@ -30,13 +30,11 @@ fun <T : Test> main(a1: A<Any?>, a2: A<Test>, b1: B<Any?>, b2: B<Test>, x: T): U
     a2.bar<T?>(null)
     a2.bar<T>(x)
 
-    // jspecify_nullness_mismatch
-    b1.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    b1.foo(null)
     b1.bar<T?>(null)
     b1.bar<T>(x)
 
-    // jspecify_nullness_mismatch
-    b2.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    b2.foo(null)
     b2.bar<T?>(null)
     b2.bar<T>(x)
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/strictMode/kt47437.fir.kt

@@ -14,5 +14,5 @@ public class Foo<T extends @Nullable Object> {
 
 // FILE: main.kt
 fun test(): Foo<String> {
-    return <!DEBUG_INFO_EXPRESSION_TYPE("Foo<kotlin.String>")!>Foo.create()<!>
+    return <!DEBUG_INFO_EXPRESSION_TYPE("Foo<kotlin.String..kotlin.String?!>")!>Foo.create()<!>
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/warnMode/NullnessUnspecifiedTypeParameter.fir.kt

@@ -14,17 +14,17 @@ public class Test {}
 
 // FILE: main.kt
 fun main(a1: NullnessUnspecifiedTypeParameter<Any>, a2: NullnessUnspecifiedTypeParameter<Any?>, x: Test): Unit {
-    a1.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a1.foo(null)
     a1.foo(1)
 
-    a2.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a2.foo(null)
     a2.foo(1)
 
-    a1.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, <!NULL_FOR_NONNULL_TYPE!>null<!>)
-    a1.bar(x, <!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a1.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, null)
+    a1.bar(x, null)
     a1.bar(x, 1)
 
-    a2.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, <!NULL_FOR_NONNULL_TYPE!>null<!>)
-    a2.bar(x, <!NULL_FOR_NONNULL_TYPE!>null<!>)
+    a2.bar(<!NULL_FOR_NONNULL_TYPE!>null<!>, null)
+    a2.bar(x, null)
     a2.bar(x, 1)
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/warnMode/SelfType.fir.kt

@@ -40,12 +40,12 @@ public class CKN extends C<@Nullable CK> {}
 // FILE: main.kt
 fun main(ak: AK, akn: AKN, bk: BK, ck: CK, ckn: CKN): Unit {
     ak.foo(ak)
-    ak.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    ak.foo(null)
 
-    akn.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>) // the corresponding warning/error is present on the Java side
+    akn.foo(null) // the corresponding warning/error is present on the Java side
 
     bk.foo(bk)
-    bk.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    bk.foo(null)
 
     ck.foo(ck)
     ck.foo(null)

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/jspecify/warnMode/TypeParameterBounds.fir.kt

@@ -29,11 +29,11 @@ fun <T : Test> main(a1: A<Any?>, a2: A<Test>, b1: B<Any?>, b2: B<Test>, x: T): U
     a2.bar<T?>(null)
     a2.bar<T>(x)
 
-    b1.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    b1.foo(null)
     b1.bar<T?>(null)
     b1.bar<T>(x)
 
-    b2.foo(<!NULL_FOR_NONNULL_TYPE!>null<!>)
+    b2.foo(null)
     b2.bar<T?>(null)
     b2.bar<T>(x)
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/misc/returnType.fir.kt

@@ -51,15 +51,15 @@ fun <R> main(a: ReturnType<R>) {
     takeNotNullStringAndNotNullK(x3)
     takeNullableStringAndNotNullK(<!ARGUMENT_TYPE_MISMATCH!>x3<!>)
 
-    val x4 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<R!!>..kotlin.Array<out R!!>")!>a.foo4<!>
+    val x4 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<R!!>..kotlin.Array<out R!!>?!")!>a.foo4<!>
     takeArrayOfNotNullString(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
     takeArrayOfNullableString(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
     takeArrayOfNotNullK(x4)
     takeArrayOfNullableK(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
 
-    val x5 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<kotlin.String?>?..kotlin.Array<out kotlin.String?>??")!>a.foo5()<!>
+    val x5 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<kotlin.String?>..kotlin.Array<out kotlin.String?>?!")!>a.foo5()<!>
     takeArrayOfNotNullString(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
-    takeArrayOfNullableString(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
+    takeArrayOfNullableString(x5)
     takeArrayOfNotNullK(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
-    takeArrayOfNullableK(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
+    takeArrayOfNullableK(x5)
 }

compiler/testData/diagnostics/foreignAnnotationsTests/java8Tests/misc/returnTypeWithWarnings.fir.kt

@@ -53,15 +53,15 @@ fun <R> main(a: ReturnTypeWithWarnings<R>) {
     takeNotNullStringAndNotNullK(x3)
     takeNullableStringAndNotNullK(<!ARGUMENT_TYPE_MISMATCH!>x3<!>)
 
-    val x4 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<R!!>..kotlin.Array<out R!!>")!>a.foo4<!>
+    val x4 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<R!!>..kotlin.Array<out R!!>?!")!>a.foo4<!>
     takeArrayOfNotNullString(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
     takeArrayOfNullableString(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
     takeArrayOfNotNullK(x4)
     takeArrayOfNullableK(<!ARGUMENT_TYPE_MISMATCH!>x4<!>)
 
-    val x5 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<kotlin.String?>?..kotlin.Array<out kotlin.String?>??")!>a.foo5()<!>
+    val x5 = <!DEBUG_INFO_EXPRESSION_TYPE("kotlin.Array<kotlin.String?>..kotlin.Array<out kotlin.String?>?!")!>a.foo5()<!>
     takeArrayOfNotNullString(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
-    takeArrayOfNullableString(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
+    takeArrayOfNullableString(x5)
     takeArrayOfNotNullK(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
-    takeArrayOfNullableK(<!ARGUMENT_TYPE_MISMATCH!>x5<!>)
+    takeArrayOfNullableK(x5)
 }

compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.kt.txt

@@ -32,9 +32,9 @@ fun testDesugaredForInList() {
 
 fun testForInArrayUnused(j: J) {
   { // BLOCK
-    val <iterator>: Iterator<@FlexibleNullability P?> = j.arrayOfNotNull().iterator()
+    val <iterator>: Iterator<@EnhancedNullability P> = j.arrayOfNotNull().iterator()
     while (<iterator>.hasNext()) { // BLOCK
-      val x: @FlexibleNullability P? = <iterator>.next()
+      val x: P = <iterator>.next() /*!! P */
     }
   }
 }
@@ -54,11 +54,11 @@ fun testForInListUse() {
 
 fun testForInArrayUse(j: J) {
   { // BLOCK
-    val <iterator>: Iterator<@FlexibleNullability P?> = j.arrayOfNotNull().iterator()
+    val <iterator>: Iterator<@EnhancedNullability P> = j.arrayOfNotNull().iterator()
     while (<iterator>.hasNext()) { // BLOCK
-      val x: @FlexibleNullability P? = <iterator>.next()
+      val x: P = <iterator>.next() /*!! P */
       { // BLOCK
-        use(s = x /*!! @FlexibleNullability P */)
+        use(s = x)
         use(s = x)
       }
     }

compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.txt

@@ -54,17 +54,18 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
     VALUE_PARAMETER name:j index:0 type:<root>.J
     BLOCK_BODY
       BLOCK type=kotlin.Unit origin=FOR_LOOP
-        VAR FOR_LOOP_ITERATOR name:tmp_2 type:kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val]
-          CALL 'public final fun iterator (): kotlin.collections.Iterator<T of kotlin.Array> [operator] declared in kotlin.Array' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
-            $this: CALL 'public open fun arrayOfNotNull (): @[EnhancedNullability] kotlin.Array<out @[FlexibleNullability] <root>.P?> declared in <root>.J' type=@[EnhancedNullability] kotlin.Array<out @[FlexibleNullability] <root>.P?> origin=null
+        VAR FOR_LOOP_ITERATOR name:tmp_2 type:kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val]
+          CALL 'public final fun iterator (): kotlin.collections.Iterator<T of kotlin.Array> [operator] declared in kotlin.Array' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
+            $this: CALL 'public open fun arrayOfNotNull (): @[EnhancedNullability] kotlin.Array<out @[EnhancedNullability] <root>.P> declared in <root>.J' type=@[EnhancedNullability] kotlin.Array<out @[EnhancedNullability] <root>.P> origin=null
               $this: GET_VAR 'j: <root>.J declared in <root>.testForInArrayUnused' type=<root>.J origin=null
         WHILE label=null origin=FOR_LOOP_INNER_WHILE
           condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [operator] declared in kotlin.collections.Iterator' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
-            $this: GET_VAR 'val tmp_2: kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val] declared in <root>.testForInArrayUnused' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
+            $this: GET_VAR 'val tmp_2: kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInArrayUnused' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
           body: BLOCK type=kotlin.Unit origin=FOR_LOOP_INNER_WHILE
-            VAR FOR_LOOP_VARIABLE name:x type:@[FlexibleNullability] <root>.P? [val]
-              CALL 'public abstract fun next (): T of kotlin.collections.Iterator [operator] declared in kotlin.collections.Iterator' type=@[FlexibleNullability] <root>.P? origin=FOR_LOOP_NEXT
-                $this: GET_VAR 'val tmp_2: kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val] declared in <root>.testForInArrayUnused' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
+            VAR FOR_LOOP_VARIABLE name:x type:<root>.P [val]
+              TYPE_OP type=<root>.P origin=IMPLICIT_NOTNULL typeOperand=<root>.P
+                CALL 'public abstract fun next (): T of kotlin.collections.Iterator [operator] declared in kotlin.collections.Iterator' type=@[EnhancedNullability] <root>.P origin=FOR_LOOP_NEXT
+                  $this: GET_VAR 'val tmp_2: kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInArrayUnused' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
   FUN name:testForInListUse visibility:public modality:FINAL <> () returnType:kotlin.Unit
     BLOCK_BODY
       BLOCK type=kotlin.Unit origin=FOR_LOOP
@@ -88,23 +89,23 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
     VALUE_PARAMETER name:j index:0 type:<root>.J
     BLOCK_BODY
       BLOCK type=kotlin.Unit origin=FOR_LOOP
-        VAR FOR_LOOP_ITERATOR name:tmp_4 type:kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val]
-          CALL 'public final fun iterator (): kotlin.collections.Iterator<T of kotlin.Array> [operator] declared in kotlin.Array' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
-            $this: CALL 'public open fun arrayOfNotNull (): @[EnhancedNullability] kotlin.Array<out @[FlexibleNullability] <root>.P?> declared in <root>.J' type=@[EnhancedNullability] kotlin.Array<out @[FlexibleNullability] <root>.P?> origin=null
+        VAR FOR_LOOP_ITERATOR name:tmp_4 type:kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val]
+          CALL 'public final fun iterator (): kotlin.collections.Iterator<T of kotlin.Array> [operator] declared in kotlin.Array' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
+            $this: CALL 'public open fun arrayOfNotNull (): @[EnhancedNullability] kotlin.Array<out @[EnhancedNullability] <root>.P> declared in <root>.J' type=@[EnhancedNullability] kotlin.Array<out @[EnhancedNullability] <root>.P> origin=null
               $this: GET_VAR 'j: <root>.J declared in <root>.testForInArrayUse' type=<root>.J origin=null
         WHILE label=null origin=FOR_LOOP_INNER_WHILE
           condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [operator] declared in kotlin.collections.Iterator' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
-            $this: GET_VAR 'val tmp_4: kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val] declared in <root>.testForInArrayUse' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
+            $this: GET_VAR 'val tmp_4: kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInArrayUse' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
           body: BLOCK type=kotlin.Unit origin=FOR_LOOP_INNER_WHILE
-            VAR FOR_LOOP_VARIABLE name:x type:@[FlexibleNullability] <root>.P? [val]
-              CALL 'public abstract fun next (): T of kotlin.collections.Iterator [operator] declared in kotlin.collections.Iterator' type=@[FlexibleNullability] <root>.P? origin=FOR_LOOP_NEXT
-                $this: GET_VAR 'val tmp_4: kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> [val] declared in <root>.testForInArrayUse' type=kotlin.collections.Iterator<@[FlexibleNullability] <root>.P?> origin=null
+            VAR FOR_LOOP_VARIABLE name:x type:<root>.P [val]
+              TYPE_OP type=<root>.P origin=IMPLICIT_NOTNULL typeOperand=<root>.P
+                CALL 'public abstract fun next (): T of kotlin.collections.Iterator [operator] declared in kotlin.collections.Iterator' type=@[EnhancedNullability] <root>.P origin=FOR_LOOP_NEXT
+                  $this: GET_VAR 'val tmp_4: kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInArrayUse' type=kotlin.collections.Iterator<@[EnhancedNullability] <root>.P> origin=null
             BLOCK type=kotlin.Unit origin=null
               CALL 'public final fun use (s: <root>.P): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
-                s: TYPE_OP type=@[FlexibleNullability] <root>.P origin=IMPLICIT_NOTNULL typeOperand=@[FlexibleNullability] <root>.P
-                  GET_VAR 'val x: @[FlexibleNullability] <root>.P? [val] declared in <root>.testForInArrayUse' type=@[FlexibleNullability] <root>.P? origin=null
+                s: GET_VAR 'val x: <root>.P [val] declared in <root>.testForInArrayUse' type=<root>.P origin=null
               CALL 'public open fun use (s: @[EnhancedNullability] <root>.P): kotlin.Unit declared in <root>.J' type=kotlin.Unit origin=null
-                s: GET_VAR 'val x: @[FlexibleNullability] <root>.P? [val] declared in <root>.testForInArrayUse' type=@[FlexibleNullability] <root>.P? origin=null
+                s: GET_VAR 'val x: <root>.P [val] declared in <root>.testForInArrayUse' type=<root>.P origin=null
   CLASS INTERFACE name:K modality:ABSTRACT visibility:public superTypes:[kotlin.Any]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.K
     FUN name:arrayOfNotNull visibility:public modality:ABSTRACT <> ($this:<root>.K) returnType:kotlin.Array<<root>.P>