diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
index 87ff8d91a40..42501e5c4cd 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt
@@ -1897,6 +1897,13 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.PLATFORM_CLASS_MAPPED_TO_KOTLIN) { firDiagnostic ->
+        PlatformClassMappedToKotlinImpl(
+            firDiagnostic.a,
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED) { firDiagnostic ->
         ExtensionInClassReferenceNotAllowedImpl(
             firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.a.fir),
diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
index c7c55a90953..332ec13633a 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt
@@ -1352,6 +1352,11 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = RedundantNullable::class
     }
 
+    abstract class PlatformClassMappedToKotlin : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = PlatformClassMappedToKotlin::class
+        abstract val kotlinClass: FqName
+    }
+
     abstract class ExtensionInClassReferenceNotAllowed : KtFirDiagnostic<KtExpression>() {
         override val diagnosticClass get() = ExtensionInClassReferenceNotAllowed::class
         abstract val referencedDeclaration: KtCallableSymbol
diff --git a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
index ee202db804a..1690cc457bc 100644
--- a/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
+++ b/analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt
@@ -1622,6 +1622,12 @@ internal class RedundantNullableImpl(
     override val token: ValidityToken,
 ) : KtFirDiagnostic.RedundantNullable(), KtAbstractFirDiagnostic<KtTypeReference>
 
+internal class PlatformClassMappedToKotlinImpl(
+    override val kotlinClass: FqName,
+    override val firDiagnostic: KtPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.PlatformClassMappedToKotlin(), KtAbstractFirDiagnostic<PsiElement>
+
 internal class ExtensionInClassReferenceNotAllowedImpl(
     override val referencedDeclaration: KtCallableSymbol,
     override val firDiagnostic: KtPsiDiagnostic,
diff --git a/compiler/fir/analysis-tests/testData/resolve/inlineClasses/inlineClassDeclaration.kt b/compiler/fir/analysis-tests/testData/resolve/inlineClasses/inlineClassDeclaration.kt
index 57cd9d018a3..14557fecc67 100644
--- a/compiler/fir/analysis-tests/testData/resolve/inlineClasses/inlineClassDeclaration.kt
+++ b/compiler/fir/analysis-tests/testData/resolve/inlineClasses/inlineClassDeclaration.kt
@@ -1,3 +1,4 @@
+// WITH_EXTENDED_CHECKERS
 class A {
     <!VALUE_CLASS_NOT_TOP_LEVEL!>inline<!> inner class B(val x: Int)
     fun foo() {
@@ -11,7 +12,7 @@ class A {
 <!VALUE_CLASS_NOT_FINAL!>sealed<!> inline class NotFinalClass3(val x: Int)
 
 <!VALUE_CLASS_CANNOT_BE_CLONEABLE, VALUE_CLASS_WITHOUT_JVM_INLINE_ANNOTATION!>value<!> class CloneableClass1(val x: Int): Cloneable
-<!VALUE_CLASS_CANNOT_BE_CLONEABLE!>inline<!> class CloneableClass2(val x: Int): java.lang.Cloneable
+<!VALUE_CLASS_CANNOT_BE_CLONEABLE!>inline<!> class CloneableClass2(val x: Int): <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Cloneable<!>
 
 open class Test
 inline class ExtendTest(val x: Int): <!SUPERTYPE_NOT_INITIALIZED, VALUE_CLASS_CANNOT_EXTEND_CLASSES!>Test<!>
diff --git a/compiler/fir/analysis-tests/testData/resolveWithStdlib/functionX.kt b/compiler/fir/analysis-tests/testData/resolveWithStdlib/functionX.kt
index ea37c0eabc7..34f2806e9cf 100644
--- a/compiler/fir/analysis-tests/testData/resolveWithStdlib/functionX.kt
+++ b/compiler/fir/analysis-tests/testData/resolveWithStdlib/functionX.kt
@@ -1,6 +1,8 @@
-import kotlin.jvm.functions.Function0
+// WITH_EXTENDED_CHECKERS
 
-val x: Function0<Int> = <!INITIALIZER_TYPE_MISMATCH!>{ 42 }<!>
+import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>kotlin.jvm.functions.Function0<!>
+
+val x: <!PLATFORM_CLASS_MAPPED_TO_KOTLIN, PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Function0<Int><!> = <!INITIALIZER_TYPE_MISMATCH!>{ 42 }<!>
 
 val y: Function1<String, String> = { it }
 
diff --git a/compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/IntersectionWithJavaString.kt b/compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/IntersectionWithJavaString.kt
index af8b5b26b4c..97c328dfdea 100644
--- a/compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/IntersectionWithJavaString.kt
+++ b/compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/IntersectionWithJavaString.kt
@@ -1,7 +1,8 @@
 // FULL_JDK
 // ISSUE: KT-48113
+// WITH_EXTENDED_CHECKERS
 
 fun collapse(path: String) {
-    val result = (path as java.lang.String).replace("123", "456")
+    val result = (path as <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.String<!>).replace("123", "456")
     if (result !== path) {}
 }
diff --git a/compiler/fir/analysis-tests/testData/resolveWithStdlib/multiModule/Basic.kt b/compiler/fir/analysis-tests/testData/resolveWithStdlib/multiModule/Basic.kt
index f185a5429b5..a1f3ea71abf 100644
--- a/compiler/fir/analysis-tests/testData/resolveWithStdlib/multiModule/Basic.kt
+++ b/compiler/fir/analysis-tests/testData/resolveWithStdlib/multiModule/Basic.kt
@@ -1,3 +1,4 @@
+// WITH_EXTENDED_CHECKERS
 // MODULE: m1
 // FILE: base.kt
 
@@ -5,7 +6,7 @@ package hello
 
 class Hello(val msg: String)
 
-class Test(val set: java.util.Set<*>)
+class Test(val set: <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.Set<*><!>)
 
 // MODULE: m2(m1)
 // FILE: user.kt
diff --git a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
index 122894963e6..b9b2fab1487 100644
--- a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
+++ b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt
@@ -657,6 +657,10 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         }
 
         val REDUNDANT_NULLABLE by warning<KtTypeReference>(PositioningStrategy.REDUNDANT_NULLABLE)
+
+        val PLATFORM_CLASS_MAPPED_TO_KOTLIN by warning<PsiElement>(PositioningStrategy.REFERENCED_NAME_BY_QUALIFIED) {
+            parameter<FqName>("kotlinClass")
+        }
     }
 
     val REFLECTION by object : DiagnosticGroup("Reflection") {
diff --git a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
index e3c8290a804..fc2dc640399 100644
--- a/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
+++ b/compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt
@@ -396,6 +396,7 @@ object FirErrors {
     val TYPE_VARIANCE_CONFLICT_IN_EXPANDED_TYPE by error4<PsiElement, FirTypeParameterSymbol, Variance, Variance, ConeKotlinType>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
     val SMARTCAST_IMPOSSIBLE by error4<KtExpression, ConeKotlinType, FirExpression, String, Boolean>()
     val REDUNDANT_NULLABLE by warning0<KtTypeReference>(SourceElementPositioningStrategies.REDUNDANT_NULLABLE)
+    val PLATFORM_CLASS_MAPPED_TO_KOTLIN by warning1<PsiElement, FqName>(SourceElementPositioningStrategies.REFERENCED_NAME_BY_QUALIFIED)
 
     // Reflection
     val EXTENSION_IN_CLASS_REFERENCE_NOT_ALLOWED by error1<KtExpression, FirCallableSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedDeclarationCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedDeclarationCheckers.kt
index d20d2129f59..c28f8272c9d 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedDeclarationCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedDeclarationCheckers.kt
@@ -11,6 +11,11 @@ import org.jetbrains.kotlin.fir.analysis.checkers.declaration.*
 import org.jetbrains.kotlin.fir.analysis.checkers.extended.*
 
 object ExtendedDeclarationCheckers : DeclarationCheckers() {
+    override val fileCheckers: Set<FirFileChecker>
+        get() = setOf(
+            PlatformClassMappedToKotlinImportsChecker
+        )
+
     override val basicDeclarationCheckers: Set<FirBasicDeclarationChecker>
         get() = setOf(
             RedundantVisibilityModifierSyntaxChecker,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedTypeCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedTypeCheckers.kt
index ab2587e463e..f6fa7002f20 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedTypeCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/ExtendedTypeCheckers.kt
@@ -5,11 +5,13 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers
 
+import org.jetbrains.kotlin.fir.analysis.checkers.extended.PlatformClassMappedToKotlinTypeRefChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.extended.RedundantNullableChecker
 import org.jetbrains.kotlin.fir.analysis.checkers.type.*
 
 object ExtendedTypeCheckers : TypeCheckers() {
     override val typeRefCheckers: Set<FirTypeRefChecker> = setOf(
-        RedundantNullableChecker
+        RedundantNullableChecker,
+        PlatformClassMappedToKotlinTypeRefChecker
     )
 }
\ No newline at end of file
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinImportsChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinImportsChecker.kt
new file mode 100644
index 00000000000..01c44bedbd6
--- /dev/null
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinImportsChecker.kt
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2021 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.analysis.checkers.extended
+
+import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirFileChecker
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.fir.declarations.FirFile
+import org.jetbrains.kotlin.fir.declarations.FirResolvedImport
+import org.jetbrains.kotlin.fir.scopes.platformClassMapper
+import org.jetbrains.kotlin.name.ClassId
+
+object PlatformClassMappedToKotlinImportsChecker : FirFileChecker() {
+    override fun check(declaration: FirFile, context: CheckerContext, reporter: DiagnosticReporter) {
+        declaration.imports.forEach { import ->
+            val importedFqName = import.importedFqName ?: return
+            if (importedFqName.isRoot || importedFqName.shortName().asString().isEmpty()) return
+            val classId = (import as? FirResolvedImport)?.resolvedParentClassId ?: ClassId.topLevel(importedFqName)
+            if (classId.asSingleFqName() != importedFqName) {
+                return
+            }
+
+            val kotlinClass = context.session.platformClassMapper.getCorrespondingKotlinClass(classId)
+            if (kotlinClass != null) {
+                reporter.reportOn(import.source, FirErrors.PLATFORM_CLASS_MAPPED_TO_KOTLIN, importedFqName, context)
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinTypeRefChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinTypeRefChecker.kt
new file mode 100644
index 00000000000..f2327e3b7a9
--- /dev/null
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/extended/PlatformClassMappedToKotlinTypeRefChecker.kt
@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2021 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.analysis.checkers.extended
+
+import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.type.FirTypeRefChecker
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.fir.scopes.platformClassMapper
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.types.classId
+
+object PlatformClassMappedToKotlinTypeRefChecker : FirTypeRefChecker() {
+    override fun check(typeRef: FirTypeRef, context: CheckerContext, reporter: DiagnosticReporter) {
+        if (typeRef is FirResolvedTypeRef) {
+            val kotlinClass = context.session.platformClassMapper.getCorrespondingKotlinClass(typeRef.type.classId)
+            if (kotlinClass != null) {
+                reporter.reportOn(typeRef.source, FirErrors.PLATFORM_CLASS_MAPPED_TO_KOTLIN, kotlinClass.asSingleFqName(), context)
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
index dac657f1adc..48114651024 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt
@@ -349,6 +349,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERRIDE_BY_INLIN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERRIDE_DEPRECATION
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.OVERRIDING_FINAL_MEMBER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PACKAGE_CANNOT_BE_IMPORTED
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PLATFORM_CLASS_MAPPED_TO_KOTLIN
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIMARY_CONSTRUCTOR_DELEGATION_CALL_EXPECTED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIMARY_CONSTRUCTOR_REQUIRED_FOR_DATA_CLASS
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.PRIVATE_CLASS_MEMBER_FROM_INLINE
@@ -624,6 +625,7 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
         map.put(SINGLETON_IN_SUPERTYPE, "Cannot inherit from a singleton")
         map.put(NULLABLE_SUPERTYPE, "A supertype cannot be nullable")
         map.put(REDUNDANT_NULLABLE, "Redundant '?'")
+        map.put(PLATFORM_CLASS_MAPPED_TO_KOTLIN, "This class shouldn't be used in Kotlin. Use {0} instead.", TO_STRING)
         map.put(MANY_CLASSES_IN_SUPERTYPE_LIST, "Only one class may appear in a supertype list")
         map.put(SUPERTYPE_APPEARS_TWICE, "A supertype appears twice")
         map.put(CLASS_IN_SUPERTYPE_FOR_ENUM, "Enum class cannot inherit from classes")
diff --git a/compiler/testData/diagnostics/tests/PackageQualified.fir.kt b/compiler/testData/diagnostics/tests/PackageQualified.fir.kt
index 9c2739ef43d..07788fdd66b 100644
--- a/compiler/testData/diagnostics/tests/PackageQualified.fir.kt
+++ b/compiler/testData/diagnostics/tests/PackageQualified.fir.kt
@@ -1,10 +1,11 @@
-// FILE: a.kt
+// WITH_EXTENDED_CHECKERS
 
+// FILE: a.kt
 
 package foobar.a
     import java.*
 
-    val a : java.util.List<Int>? = null
+    val a : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.List<Int><!>? = null
     val a2 : <!UNRESOLVED_REFERENCE!>util.List<Int><!>? = null
     val a3 : <!UNRESOLVED_REFERENCE!>LinkedList<Int><!>? = null
 
diff --git a/compiler/testData/diagnostics/tests/PackageQualified.kt b/compiler/testData/diagnostics/tests/PackageQualified.kt
index 4079d93c9c3..b01ed8e3902 100644
--- a/compiler/testData/diagnostics/tests/PackageQualified.kt
+++ b/compiler/testData/diagnostics/tests/PackageQualified.kt
@@ -1,5 +1,6 @@
-// FILE: a.kt
+// WITH_EXTENDED_CHECKERS
 
+// FILE: a.kt
 
 package foobar.a
     import java.*
diff --git a/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.kt b/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.kt
index 2a428d0261d..3b342cc6d35 100644
--- a/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.kt
+++ b/compiler/testData/diagnostics/tests/ProjectionsInSupertypes.kt
@@ -1,3 +1,4 @@
+// WITH_EXTENDED_CHECKERS
 interface A<T> {}
 interface B<T> {}
 interface C<T> {}
diff --git a/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt b/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt
deleted file mode 100644
index e7a4bbd2c5f..00000000000
--- a/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.fir.kt
+++ /dev/null
@@ -1,21 +0,0 @@
-// Fixpoint generic in Java: Enum<T extends Enum<T>>
-fun test(a : java.lang.annotation.RetentionPolicy) {
-
-}
-
-fun test() {
-  java.util.Collections.<!NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER!>emptyList<!>()
-  val a : Collection<String>? = java.util.Collections.emptyList()
-}
-
-fun test(a : java.lang.Comparable<Int>) {
-
-}
-
-fun test(a : java.util.ArrayList<Int>) {
-
-}
-
-fun test(a : java.lang.Class<Int>) {
-
-}
diff --git a/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.kt b/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.kt
index 6d440cd35e6..5419886d959 100644
--- a/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.kt
+++ b/compiler/testData/diagnostics/tests/ResolveOfJavaGenerics.kt
@@ -1,3 +1,6 @@
+// FIR_IDENTICAL
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// WITH_EXTENDED_CHECKERS
 // Fixpoint generic in Java: Enum<T extends Enum<T>>
 fun test(a : java.lang.annotation.RetentionPolicy) {
 
diff --git a/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt b/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt
index 20c9a9e4cbf..ac1de909e49 100644
--- a/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt
+++ b/compiler/testData/diagnostics/tests/ResolveToJava.fir.kt
@@ -1,6 +1,7 @@
 // !CHECK_TYPE
 // SKIP_JAVAC
 // FULL_JDK
+// WITH_EXTENDED_CHECKERS
 
 // FILE: a.kt
 
@@ -9,17 +10,17 @@ import java.util.*
 import utils.*
 
 import java.io.PrintStream
-import java.lang.Comparable as Com
+import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<!> as Com
 
 val l : MutableList<in Int> = ArrayList<Int>()
 
-fun test(l : java.util.List<Int>) {
-  val x : <!UNRESOLVED_REFERENCE!>java.List<!>
-  val y : java.util.List<Int>
-  val b : java.lang.Object
-  val z : <!UNRESOLVED_REFERENCE!>java.utils.List<Int><!>
+fun test(l : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.List<Int><!>) {
+  val <!UNUSED_VARIABLE!>x<!> : <!UNRESOLVED_REFERENCE!>java.List<!>
+  val <!UNUSED_VARIABLE!>y<!> : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.List<Int><!>
+  val <!UNUSED_VARIABLE!>b<!> : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Object<!>
+  val <!UNUSED_VARIABLE!>z<!> : <!UNRESOLVED_REFERENCE!>java.utils.List<Int><!>
 
-  val f : java.io.File? = null
+  val <!UNUSED_VARIABLE!>f<!> : java.io.File? = null
 
   Collections.<!FUNCTION_CALL_EXPECTED!>emptyList<!>
   Collections.<!FUNCTION_CALL_EXPECTED!>emptyList<!><<!CANNOT_INFER_PARAMETER_TYPE!>Int<!>>
@@ -32,7 +33,7 @@ fun test(l : java.util.List<Int>) {
   <!NO_COMPANION_OBJECT!>List<Int><!>
 
 
-  val o = "sdf" as Object
+  val <!UNUSED_VARIABLE!>o<!> = "sdf" as <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!>
 
   try {
     // ...
@@ -43,9 +44,9 @@ fun test(l : java.util.List<Int>) {
 
   PrintStream("sdf")
 
-  val c : Com<Int>? = null
+  val c : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Com<Int><!>? = null
 
-  checkSubtype<java.lang.Comparable<Int>?>(c)
+  checkSubtype<<!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<Int><!>?>(c)
 
 //  Collections.sort<Integer>(ArrayList<Integer>())
   xxx.<!UNRESOLVED_REFERENCE!>Class<!>()
diff --git a/compiler/testData/diagnostics/tests/ResolveToJava.kt b/compiler/testData/diagnostics/tests/ResolveToJava.kt
index 41451b3c014..c40467e0ca5 100644
--- a/compiler/testData/diagnostics/tests/ResolveToJava.kt
+++ b/compiler/testData/diagnostics/tests/ResolveToJava.kt
@@ -1,6 +1,7 @@
 // !CHECK_TYPE
 // SKIP_JAVAC
 // FULL_JDK
+// WITH_EXTENDED_CHECKERS
 
 // FILE: a.kt
 
diff --git a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt
index bdac51dc5c4..85d158092a2 100644
--- a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt
+++ b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.fir.kt
@@ -1,6 +1,7 @@
 // JAVAC_EXPECTED_FILE
-interface MyTrait: <!INTERFACE_WITH_SUPERCLASS!>Object<!> {
+// WITH_EXTENDED_CHECKERS
+interface MyTrait: <!INTERFACE_WITH_SUPERCLASS, PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!> {
     override fun toString(): String
     public override fun finalize()
-    public <!OVERRIDING_FINAL_MEMBER!>override<!> fun wait()
+    <!REDUNDANT_VISIBILITY_MODIFIER!>public<!> <!OVERRIDING_FINAL_MEMBER!>override<!> fun wait()
 }
diff --git a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.kt b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.kt
index c4d1d299e45..cb7995c1053 100644
--- a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.kt
+++ b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.kt
@@ -1,4 +1,5 @@
 // JAVAC_EXPECTED_FILE
+// WITH_EXTENDED_CHECKERS
 interface MyTrait: <!INTERFACE_WITH_SUPERCLASS, PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!> {
     override fun toString(): String
     public override fun finalize()
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt
index 6175e519d3b..f37772a7de5 100644
--- a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.fir.kt
@@ -1,4 +1,6 @@
 // JAVAC_EXPECTED_FILE
+// WITH_EXTENDED_CHECKERS
+
 class TestIface(r : Runnable) : Runnable by r {}
 
-class TestObject(o : Object) : <!DELEGATION_NOT_TO_INTERFACE, SUPERTYPE_NOT_INITIALIZED!>Object<!> by o {}
+class TestObject(o : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!>) : <!DELEGATION_NOT_TO_INTERFACE, PLATFORM_CLASS_MAPPED_TO_KOTLIN, PLATFORM_CLASS_MAPPED_TO_KOTLIN, PLATFORM_CLASS_MAPPED_TO_KOTLIN, SUPERTYPE_NOT_INITIALIZED!>Object<!> by o {}
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.kt b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.kt
index 570a40e173e..7ccdd29d6e0 100644
--- a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.kt
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.kt
@@ -1,4 +1,6 @@
 // JAVAC_EXPECTED_FILE
+// WITH_EXTENDED_CHECKERS
+
 class TestIface(r : Runnable) : Runnable by r {}
 
 class TestObject(o : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!>) : <!DELEGATION_NOT_TO_INTERFACE, PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Object<!> by o {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt b/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt
deleted file mode 100644
index dcd261d0336..00000000000
--- a/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.fir.kt
+++ /dev/null
@@ -1,6 +0,0 @@
-import java.lang.reflect.*
-import java.util.List
-
-fun foo(
-        p1: Array<String> /* should be resolved to kotlin.Array */,
-        p2: List<String> /* should be resolved to java.util.List */) { }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.kt b/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.kt
index 6a93d38c601..369678e64f0 100644
--- a/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.kt
+++ b/compiler/testData/diagnostics/tests/imports/DefaultImportsPriority.kt
@@ -1,3 +1,6 @@
+// FIR_IDENTICAL
+// WITH_EXTENDED_CHECKERS
+
 import java.lang.reflect.*
 import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.List<!>
 
diff --git a/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt
index af3c1ad5c1a..69ddadcf15d 100644
--- a/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt
+++ b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.fir.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
 package i
 
@@ -7,7 +8,7 @@ import java.util.*
 import checkSubtype
 
 fun <T, R> Collection<T>.map1(f : (T) -> R) : List<R> {<!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>}<!>
-fun <T, R> java.lang.Iterable<T>.map1(f : (T) -> R) : List<R> {<!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>}<!>
+fun <T, R> <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Iterable<T><!>.map1(f : (T) -> R) : List<R> {<!NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY!>}<!>
 
 fun test(list: List<Int>) {
     val res = list.map1 { it }
@@ -16,7 +17,7 @@ fun test(list: List<Int>) {
 }
 
 fun <T> Collection<T>.foo() {}
-fun <T> java.lang.Iterable<T>.foo() {}
+fun <T> <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Iterable<T><!>.foo() {}
 
 fun test1(list: List<Int>) {
     val res = list.foo()
diff --git a/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.kt b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.kt
index bd87a1cfbbb..535fb9c8868 100644
--- a/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.kt
+++ b/compiler/testData/diagnostics/tests/inference/mostSpecificAfterInference.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
 package i
 
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt
deleted file mode 100644
index f362ec33d42..00000000000
--- a/compiler/testData/diagnostics/tests/j+k/kt2606.fir.kt
+++ /dev/null
@@ -1,11 +0,0 @@
-//KT-2606 Filter java.util.* import
-package n
-
-import java.util.*
-import java.lang.annotation.*
-
-fun bar() : Iterator<Int>? {
-    val i : Iterable<Integer>
-    val a : Annotation
-    return null
-}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2606.kt b/compiler/testData/diagnostics/tests/j+k/kt2606.kt
index 4ec58443fd6..ce35e333a30 100644
--- a/compiler/testData/diagnostics/tests/j+k/kt2606.kt
+++ b/compiler/testData/diagnostics/tests/j+k/kt2606.kt
@@ -1,3 +1,6 @@
+// FIR_IDENTICAL
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+// WITH_EXTENDED_CHECKERS
 //KT-2606 Filter java.util.* import
 package n
 
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt b/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt
index 19abd5e7c48..2036ee75fc8 100644
--- a/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt
+++ b/compiler/testData/diagnostics/tests/j+k/kt2641.fir.kt
@@ -1,20 +1,21 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
 package a
 
-import java.util.Iterator
-import java.lang.Comparable as Comp
+import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.Iterator<!>
+import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<!> as Comp
 
 import checkSubtype
 
-fun bar(any: Any): java.lang.Iterable<Int>? {
-    val a: java.lang.Comparable<String>? = null
-    val b: Iterable<Integer>
-    val c : Iterator<String>? = null
+fun bar(any: Any): <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Iterable<Int><!>? {
+    val <!UNUSED_VARIABLE!>a<!>: <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<String><!>? = null
+    val <!UNUSED_VARIABLE!>b<!>: Iterable<<!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Integer<!>>
+    val <!UNUSED_VARIABLE!>c<!> : <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Iterator<String><!>? = null
 
-    if (any is Iterator<*>) {
-        checkSubtype<Iterator<*>>(any)
+    if (any is <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Iterator<*><!>) {
+        checkSubtype<<!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Iterator<*><!>>(any)
     }
-    any as Iterator<*>
+    any as <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Iterator<*><!>
     return null
 }
diff --git a/compiler/testData/diagnostics/tests/j+k/kt2641.kt b/compiler/testData/diagnostics/tests/j+k/kt2641.kt
index b16912b65dd..5b9eb5c00b3 100644
--- a/compiler/testData/diagnostics/tests/j+k/kt2641.kt
+++ b/compiler/testData/diagnostics/tests/j+k/kt2641.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
 package a
 
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
index 561121eb688..b85a1fe3067 100644
--- a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.fir.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 //KT-1778 Automatically cast error
 package kt1778
 
@@ -6,7 +7,7 @@ import checkSubtype
 
 fun main(args : Array<String>) {
     val x = checkSubtype<Any>(args[0])
-    if(x is java.lang.CharSequence) {
+    if(x is <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.CharSequence<!>) {
         if (<!EQUALITY_NOT_APPLICABLE!>"a" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // OK
         if (<!EQUALITY_NOT_APPLICABLE!>"a" == x<!> || <!EQUALITY_NOT_APPLICABLE!>"b" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // <– THEN ERROR
         if (<!EQUALITY_NOT_APPLICABLE!>"a" == x<!> && <!EQUALITY_NOT_APPLICABLE!>"a" == x<!>) x.<!FUNCTION_CALL_EXPECTED!>length<!> else x.length() // <– ELSE ERROR
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.kt
index b016144bed1..c541af9013a 100644
--- a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.kt
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1778.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 //KT-1778 Automatically cast error
 package kt1778
 
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.kt b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.kt
index b613a783b5c..e3a0a187ab5 100644
--- a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.kt
+++ b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullable.kt
@@ -1,3 +1,4 @@
+// WITH_EXTENDED_CHECKERS
 class Generic<T>
 
 fun redundantNullable(
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.kt b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.kt
index 62de851c105..2d7395dfe1d 100644
--- a/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.kt
+++ b/compiler/testData/diagnostics/tests/nullableTypes/redundantNullableInSupertype.kt
@@ -1,3 +1,4 @@
+// WITH_EXTENDED_CHECKERS
 interface A
 interface X: A<!NULLABLE_SUPERTYPE!>?<!><!REDUNDANT_NULLABLE!>?<!> {
 
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt b/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt
deleted file mode 100644
index bc1521356d2..00000000000
--- a/compiler/testData/diagnostics/tests/regressions/Jet72.fir.kt
+++ /dev/null
@@ -1,18 +0,0 @@
-// JET-72 Type inference doesn't work when iterating over ArrayList
-
-import java.util.ArrayList
-
-abstract class Item(val room: Object) {
-   abstract val name : String
-}
-
-val items: ArrayList<Item> = ArrayList<Item>()
-
-fun test(room : Object) {
-  for(item: Item? in items) {
-    if (item?.room === room) {
-      // item?.room is not null
-      System.out.println("You see " + <!SAFE_CALL_WILL_CHANGE_NULLABILITY!>item<!UNNECESSARY_SAFE_CALL!>?.<!>name<!>)
-    }
-  }
-}
diff --git a/compiler/testData/diagnostics/tests/regressions/Jet72.kt b/compiler/testData/diagnostics/tests/regressions/Jet72.kt
index 2b84212aa4a..16a4f674ac4 100644
--- a/compiler/testData/diagnostics/tests/regressions/Jet72.kt
+++ b/compiler/testData/diagnostics/tests/regressions/Jet72.kt
@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+// WITH_EXTENDED_CHECKERS
 // JET-72 Type inference doesn't work when iterating over ArrayList
 
 import java.util.ArrayList
diff --git a/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt
index 06825f13115..8762c1cb2ed 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt334.fir.kt
@@ -1,8 +1,9 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
-import java.lang.Comparable as Comparable
+import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<!> as Comparable
 
-fun f(c: Comparable<*>) {
+fun f(c: <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Comparable<*><!>) {
     checkSubtype<kotlin.Comparable<*>>(<!ARGUMENT_TYPE_MISMATCH!>c<!>)
-    checkSubtype<java.lang.Comparable<*>>(c)
-}
\ No newline at end of file
+    checkSubtype<<!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<*><!>>(c)
+}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt334.kt b/compiler/testData/diagnostics/tests/regressions/kt334.kt
index 3451af4ed2b..9a2130f0c61 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt334.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt334.kt
@@ -1,4 +1,5 @@
 // !CHECK_TYPE
+// WITH_EXTENDED_CHECKERS
 
 import <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.lang.Comparable<!> as Comparable
 
diff --git a/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt
deleted file mode 100644
index 29c44271977..00000000000
--- a/compiler/testData/diagnostics/tests/regressions/kt498.fir.kt
+++ /dev/null
@@ -1,8 +0,0 @@
-// JAVAC_EXPECTED_FILE
-// KT-498 Very strange error in the type checker
-
-class IdUnavailableException() : Exception() {}
-
-fun <T : Any> T.getJavaClass() : Class<T> {
-    return ((this as Object).getClass()) <!UNCHECKED_CAST!>as Class<T><!> // Some error here, because of Exception() used above. ?!!!
-}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt498.kt b/compiler/testData/diagnostics/tests/regressions/kt498.kt
index 4df3c6fa476..77c546d6d79 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt498.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt498.kt
@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+// WITH_EXTENDED_CHECKERS
 // JAVAC_EXPECTED_FILE
 // KT-498 Very strange error in the type checker
 
diff --git a/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt b/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt
deleted file mode 100644
index 7c87483714c..00000000000
--- a/compiler/testData/diagnostics/tests/regressions/kt716.fir.kt
+++ /dev/null
@@ -1,16 +0,0 @@
-// KT-716 Type inference failed
-
-class TypeInfo<T>
-
-fun <T> typeinfo() : TypeInfo<T> = null <!CAST_NEVER_SUCCEEDS!>as<!> TypeInfo<T>
-
-fun <T> TypeInfo<T>.getJavaClass() : java.lang.Class<T> {
-    val t : java.lang.Object = this as java.lang.Object
-    return t.getClass() <!UNCHECKED_CAST!>as java.lang.Class<T><!> // inferred type is Object but Serializable was expected
-}
-
-fun <T> getJavaClass() = typeinfo<T>().getJavaClass()
-
-fun main() {
-    System.out.println(getJavaClass<String>())
-}
diff --git a/compiler/testData/diagnostics/tests/regressions/kt716.kt b/compiler/testData/diagnostics/tests/regressions/kt716.kt
index 171d8986fc8..91901b113ad 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt716.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt716.kt
@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+// WITH_EXTENDED_CHECKERS
 // KT-716 Type inference failed
 
 class TypeInfo<T>
diff --git a/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt b/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt
deleted file mode 100644
index 3864f5105af..00000000000
--- a/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.fir.kt
+++ /dev/null
@@ -1,7 +0,0 @@
-import java.util.ArrayList
-
-fun foo(p: java.util.List<String>) {
-    p.iterator(); // forcing resolve of java.util.List.iterator()
-
-    ArrayList<String>().iterator(); // this provoked exception in SignaturesPropagationData
-}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.kt b/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.kt
index 93f595a6f9a..b291496b3f1 100644
--- a/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.kt
+++ b/compiler/testData/diagnostics/tests/regressions/resolveSubclassOfList.kt
@@ -1,3 +1,5 @@
+// FIR_IDENTICAL
+// WITH_EXTENDED_CHECKERS
 import java.util.ArrayList
 
 fun foo(p: <!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>java.util.List<String><!>) {
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt b/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt
index c2d2227d2e5..81d23b2c0d2 100644
--- a/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt
+++ b/compiler/testData/diagnostics/tests/scopes/visibility2.fir.kt
@@ -1,5 +1,7 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 // JAVAC_EXPECTED_FILE
+// WITH_EXTENDED_CHECKERS
+
 //FILE:a.kt
 package a
 
@@ -44,6 +46,6 @@ class Q {
 }
 
 //check that 'toString' can be invoked without specifying return type
-class NewClass : java.util.ArrayList<Integer>() {
-    public override fun toString() = "a"
+class NewClass : java.util.ArrayList<<!PLATFORM_CLASS_MAPPED_TO_KOTLIN!>Integer<!>>() {
+    <!REDUNDANT_VISIBILITY_MODIFIER!>public<!> override fun toString() = "a"
 }
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility2.kt b/compiler/testData/diagnostics/tests/scopes/visibility2.kt
index 85d0603543c..6363af5b456 100644
--- a/compiler/testData/diagnostics/tests/scopes/visibility2.kt
+++ b/compiler/testData/diagnostics/tests/scopes/visibility2.kt
@@ -1,5 +1,7 @@
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 // JAVAC_EXPECTED_FILE
+// WITH_EXTENDED_CHECKERS
+
 //FILE:a.kt
 package a