diff --git a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/ErrorListDiagnosticListRenderer.kt b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/ErrorListDiagnosticListRenderer.kt
index 865cd37f8b7..7d8b69eae2f 100644
--- a/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/ErrorListDiagnosticListRenderer.kt
+++ b/compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/ErrorListDiagnosticListRenderer.kt
@@ -89,6 +89,9 @@ object ErrorListDiagnosticListRenderer : DiagnosticListRenderer() {
             }
             print(">")
         }
+        if (type.isMarkedNullable) {
+            print("?")
+        }
     }
 
     private fun SmartPrinter.printTypeArgument(typeArgument: KTypeProjection) {
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnostic.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnostic.kt
index 12a77829b42..728335ae7ec 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnostic.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnostic.kt
@@ -33,25 +33,25 @@ sealed class FirSimpleDiagnostic<out E : FirSourceElement> : FirDiagnostic<E>()
     abstract override val factory: FirDiagnosticFactory0<*>
 }
 
-sealed class FirDiagnosticWithParameters1<out E : FirSourceElement, A : Any> : FirDiagnostic<E>() {
+sealed class FirDiagnosticWithParameters1<out E : FirSourceElement, A> : FirDiagnostic<E>() {
     abstract val a: A
     abstract override val factory: FirDiagnosticFactory1<*, A>
 }
 
-sealed class FirDiagnosticWithParameters2<out E : FirSourceElement, A : Any, B : Any> : FirDiagnostic<E>() {
+sealed class FirDiagnosticWithParameters2<out E : FirSourceElement, A, B> : FirDiagnostic<E>() {
     abstract val a: A
     abstract val b: B
     abstract override val factory: FirDiagnosticFactory2<*, A, B>
 }
 
-sealed class FirDiagnosticWithParameters3<out E : FirSourceElement, A : Any, B : Any, C : Any> : FirDiagnostic<E>() {
+sealed class FirDiagnosticWithParameters3<out E : FirSourceElement, A, B, C> : FirDiagnostic<E>() {
     abstract val a: A
     abstract val b: B
     abstract val c: C
     abstract override val factory: FirDiagnosticFactory3<*, A, B, C>
 }
 
-sealed class FirDiagnosticWithParameters4<out E : FirSourceElement, A : Any, B : Any, C : Any, D : Any> : FirDiagnostic<E>() {
+sealed class FirDiagnosticWithParameters4<out E : FirSourceElement, A, B, C, D> : FirDiagnostic<E>() {
     abstract val a: A
     abstract val b: B
     abstract val c: C
@@ -77,14 +77,14 @@ data class FirPsiSimpleDiagnostic<P : PsiElement>(
     override val factory: FirDiagnosticFactory0<P>
 ) : FirSimpleDiagnostic<FirPsiSourceElement<P>>(), FirPsiDiagnostic<P>
 
-data class FirPsiDiagnosticWithParameters1<P : PsiElement, A : Any>(
+data class FirPsiDiagnosticWithParameters1<P : PsiElement, A>(
     override val element: FirPsiSourceElement<P>,
     override val a: A,
     override val severity: Severity,
     override val factory: FirDiagnosticFactory1<P, A>
 ) : FirDiagnosticWithParameters1<FirPsiSourceElement<P>, A>(), FirPsiDiagnostic<P>
 
-data class FirPsiDiagnosticWithParameters2<P : PsiElement, A : Any, B : Any>(
+data class FirPsiDiagnosticWithParameters2<P : PsiElement, A, B>(
     override val element: FirPsiSourceElement<P>,
     override val a: A,
     override val b: B,
@@ -92,7 +92,7 @@ data class FirPsiDiagnosticWithParameters2<P : PsiElement, A : Any, B : Any>(
     override val factory: FirDiagnosticFactory2<P, A, B>
 ) : FirDiagnosticWithParameters2<FirPsiSourceElement<P>, A, B>(), FirPsiDiagnostic<P>
 
-data class FirPsiDiagnosticWithParameters3<P : PsiElement, A : Any, B : Any, C : Any>(
+data class FirPsiDiagnosticWithParameters3<P : PsiElement, A, B, C>(
     override val element: FirPsiSourceElement<P>,
     override val a: A,
     override val b: B,
@@ -101,7 +101,7 @@ data class FirPsiDiagnosticWithParameters3<P : PsiElement, A : Any, B : Any, C :
     override val factory: FirDiagnosticFactory3<P, A, B, C>
 ) : FirDiagnosticWithParameters3<FirPsiSourceElement<P>, A, B, C>(), FirPsiDiagnostic<P>
 
-data class FirPsiDiagnosticWithParameters4<P : PsiElement, A : Any, B : Any, C : Any, D : Any>(
+data class FirPsiDiagnosticWithParameters4<P : PsiElement, A, B, C, D>(
     override val element: FirPsiSourceElement<P>,
     override val a: A,
     override val b: B,
@@ -123,14 +123,14 @@ data class FirLightSimpleDiagnostic(
     override val factory: FirDiagnosticFactory0<*>
 ) : FirSimpleDiagnostic<FirLightSourceElement>(), FirLightDiagnostic
 
-data class FirLightDiagnosticWithParameters1<A : Any>(
+data class FirLightDiagnosticWithParameters1<A>(
     override val element: FirLightSourceElement,
     override val a: A,
     override val severity: Severity,
     override val factory: FirDiagnosticFactory1<*, A>
 ) : FirDiagnosticWithParameters1<FirLightSourceElement, A>(), FirLightDiagnostic
 
-data class FirLightDiagnosticWithParameters2<A : Any, B : Any>(
+data class FirLightDiagnosticWithParameters2<A, B>(
     override val element: FirLightSourceElement,
     override val a: A,
     override val b: B,
@@ -138,7 +138,7 @@ data class FirLightDiagnosticWithParameters2<A : Any, B : Any>(
     override val factory: FirDiagnosticFactory2<*, A, B>
 ) : FirDiagnosticWithParameters2<FirLightSourceElement, A, B>(), FirLightDiagnostic
 
-data class FirLightDiagnosticWithParameters3<A : Any, B : Any, C : Any>(
+data class FirLightDiagnosticWithParameters3<A, B, C>(
     override val element: FirLightSourceElement,
     override val a: A,
     override val b: B,
@@ -147,7 +147,7 @@ data class FirLightDiagnosticWithParameters3<A : Any, B : Any, C : Any>(
     override val factory: FirDiagnosticFactory3<*, A, B, C>
 ) : FirDiagnosticWithParameters3<FirLightSourceElement, A, B, C>(), FirLightDiagnostic
 
-data class FirLightDiagnosticWithParameters4<A : Any, B : Any, C : Any, D : Any>(
+data class FirLightDiagnosticWithParameters4<A, B, C, D>(
     override val element: FirLightSourceElement,
     override val a: A,
     override val b: B,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactory.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactory.kt
index 29329317f03..27eace6946e 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactory.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactory.kt
@@ -55,7 +55,7 @@ class FirDiagnosticFactory0<P : PsiElement>(
     }
 }
 
-class FirDiagnosticFactory1<P : PsiElement, A : Any>(
+class FirDiagnosticFactory1<P : PsiElement, A>(
     name: String,
     severity: Severity,
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT,
@@ -76,7 +76,7 @@ class FirDiagnosticFactory1<P : PsiElement, A : Any>(
     }
 }
 
-class FirDiagnosticFactory2<P : PsiElement, A : Any, B : Any>(
+class FirDiagnosticFactory2<P : PsiElement, A, B>(
     name: String,
     severity: Severity,
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT,
@@ -98,7 +98,7 @@ class FirDiagnosticFactory2<P : PsiElement, A : Any, B : Any>(
     }
 }
 
-class FirDiagnosticFactory3<P : PsiElement, A : Any, B : Any, C : Any>(
+class FirDiagnosticFactory3<P : PsiElement, A, B, C>(
     name: String,
     severity: Severity,
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT,
@@ -121,7 +121,7 @@ class FirDiagnosticFactory3<P : PsiElement, A : Any, B : Any, C : Any>(
     }
 }
 
-class FirDiagnosticFactory4<P : PsiElement, A : Any, B : Any, C : Any, D : Any>(
+class FirDiagnosticFactory4<P : PsiElement, A, B, C, D>(
     name: String,
     severity: Severity,
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT,
@@ -152,13 +152,13 @@ fun <P : PsiElement> FirDiagnosticFactory0<P>.on(element: FirSourceElement?): Fi
     return element?.let { on(it) }
 }
 
-fun <P : PsiElement, A : Any> FirDiagnosticFactory1<P, A>.on(
+fun <P : PsiElement, A> FirDiagnosticFactory1<P, A>.on(
     element: FirSourceElement?, a: A
 ): FirDiagnosticWithParameters1<*, A>? {
     return element?.let { on(it, a) }
 }
 
-fun <P : PsiElement, A : Any, B : Any> FirDiagnosticFactory2<P, A, B>.on(
+fun <P : PsiElement, A, B> FirDiagnosticFactory2<P, A, B>.on(
     element: FirSourceElement?,
     a: A,
     b: B
@@ -166,7 +166,7 @@ fun <P : PsiElement, A : Any, B : Any> FirDiagnosticFactory2<P, A, B>.on(
     return element?.let { on(it, a, b) }
 }
 
-fun <P : PsiElement, A : Any, B : Any, C : Any> FirDiagnosticFactory3<P, A, B, C>.on(
+fun <P : PsiElement, A, B, C> FirDiagnosticFactory3<P, A, B, C>.on(
     element: FirSourceElement?,
     a: A,
     b: B,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryDsl.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryDsl.kt
index 0eae8482d34..68c9cba9632 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryDsl.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryDsl.kt
@@ -16,19 +16,19 @@ fun <P : PsiElement> warning0(
     return DiagnosticFactory0DelegateProvider(Severity.WARNING, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any> warning1(
+fun <P : PsiElement, A> warning1(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory1DelegateProvider<P, A> {
     return DiagnosticFactory1DelegateProvider(Severity.WARNING, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any, B : Any> warning2(
+fun <P : PsiElement, A, B> warning2(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory2DelegateProvider<P, A, B> {
     return DiagnosticFactory2DelegateProvider(Severity.WARNING, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any, B : Any, C : Any> warning3(
+fun <P : PsiElement, A, B, C> warning3(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory3DelegateProvider<P, A, B, C> {
     return DiagnosticFactory3DelegateProvider(Severity.WARNING, positioningStrategy)
@@ -40,25 +40,25 @@ fun <P : PsiElement> error0(
     return DiagnosticFactory0DelegateProvider(Severity.ERROR, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any> error1(
+fun <P : PsiElement, A> error1(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory1DelegateProvider<P, A> {
     return DiagnosticFactory1DelegateProvider(Severity.ERROR, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any, B : Any> error2(
+fun <P : PsiElement, A, B> error2(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory2DelegateProvider<P, A, B> {
     return DiagnosticFactory2DelegateProvider(Severity.ERROR, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any, B : Any, C : Any> error3(
+fun <P : PsiElement, A, B, C> error3(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory3DelegateProvider<P, A, B, C> {
     return DiagnosticFactory3DelegateProvider(Severity.ERROR, positioningStrategy)
 }
 
-fun <P : PsiElement, A : Any, B : Any, C : Any, D : Any> error4(
+fun <P : PsiElement, A, B, C, D> error4(
     positioningStrategy: SourceElementPositioningStrategy<P> = SourceElementPositioningStrategy.DEFAULT
 ): DiagnosticFactory4DelegateProvider<P, A, B, C, D> {
     return DiagnosticFactory4DelegateProvider(Severity.ERROR, positioningStrategy)
@@ -75,7 +75,7 @@ class DiagnosticFactory0DelegateProvider<P : PsiElement>(
     }
 }
 
-class DiagnosticFactory1DelegateProvider<P : PsiElement, A : Any>(
+class DiagnosticFactory1DelegateProvider<P : PsiElement, A>(
     private val severity: Severity,
     private val positioningStrategy: SourceElementPositioningStrategy<P>
 ) {
@@ -84,7 +84,7 @@ class DiagnosticFactory1DelegateProvider<P : PsiElement, A : Any>(
     }
 }
 
-class DiagnosticFactory2DelegateProvider<P : PsiElement, A : Any, B : Any>(
+class DiagnosticFactory2DelegateProvider<P : PsiElement, A, B>(
     private val severity: Severity,
     private val positioningStrategy: SourceElementPositioningStrategy<P>
 ) {
@@ -93,7 +93,7 @@ class DiagnosticFactory2DelegateProvider<P : PsiElement, A : Any, B : Any>(
     }
 }
 
-class DiagnosticFactory3DelegateProvider<P : PsiElement, A : Any, B : Any, C : Any>(
+class DiagnosticFactory3DelegateProvider<P : PsiElement, A, B, C>(
     private val severity: Severity,
     private val positioningStrategy: SourceElementPositioningStrategy<P>
 ) {
@@ -102,7 +102,7 @@ class DiagnosticFactory3DelegateProvider<P : PsiElement, A : Any, B : Any, C : A
     }
 }
 
-class DiagnosticFactory4DelegateProvider<P : PsiElement, A : Any, B : Any, C : Any, D : Any>(
+class DiagnosticFactory4DelegateProvider<P : PsiElement, A, B, C, D>(
     private val severity: Severity,
     private val positioningStrategy: SourceElementPositioningStrategy<P>
 ) {
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryToRendererMap.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryToRendererMap.kt
index 8c7041b0a27..7ec913c5e20 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryToRendererMap.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticFactoryToRendererMap.kt
@@ -18,7 +18,7 @@ class FirDiagnosticFactoryToRendererMap(val name: String) {
         put(factory, SimpleFirDiagnosticRenderer(message))
     }
 
-    fun <A : Any> put(
+    fun <A> put(
         factory: FirDiagnosticFactory1<*, A>,
         message: String,
         rendererA: DiagnosticParameterRenderer<A>?
@@ -26,7 +26,7 @@ class FirDiagnosticFactoryToRendererMap(val name: String) {
         put(factory, FirDiagnosticWithParameters1Renderer(message, rendererA))
     }
 
-    fun <A : Any, B : Any> put(
+    fun <A, B> put(
         factory: FirDiagnosticFactory2<*, A, B>,
         message: String,
         rendererA: DiagnosticParameterRenderer<A>?,
@@ -35,7 +35,7 @@ class FirDiagnosticFactoryToRendererMap(val name: String) {
         put(factory, FirDiagnosticWithParameters2Renderer(message, rendererA, rendererB))
     }
 
-    fun <A : Any, B : Any, C : Any> put(
+    fun <A, B, C> put(
         factory: FirDiagnosticFactory3<*, A, B, C>,
         message: String,
         rendererA: DiagnosticParameterRenderer<A>?,
@@ -45,7 +45,7 @@ class FirDiagnosticFactoryToRendererMap(val name: String) {
         put(factory, FirDiagnosticWithParameters3Renderer(message, rendererA, rendererB, rendererC))
     }
 
-    fun <A : Any, B : Any, C : Any, D : Any> put(
+    fun <A, B, C, D> put(
         factory: FirDiagnosticFactory4<*, A, B, C, D>,
         message: String,
         rendererA: DiagnosticParameterRenderer<A>?,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderer.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderer.kt
index 2473f08d754..e13eb34ced3 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderer.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderer.kt
@@ -21,22 +21,22 @@ sealed class AbstractFirDiagnosticWithParametersRenderer<D : FirDiagnostic<*>>(
     protected val message: String
 ) : FirDiagnosticRenderer<D>, AbstractDiagnosticWithParametersRenderer<D>(message)
 
-class FirDiagnosticWithParameters1Renderer<A : Any>(
+class FirDiagnosticWithParameters1Renderer<A>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
 ) : AbstractFirDiagnosticWithParametersRenderer<FirDiagnosticWithParameters1<*, A>>(message) {
-    override fun renderParameters(diagnostic: FirDiagnosticWithParameters1<*, A>): Array<out Any> {
+    override fun renderParameters(diagnostic: FirDiagnosticWithParameters1<*, A>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a)
         return arrayOf(renderParameter(diagnostic.a, rendererForA, context))
     }
 }
 
-class FirDiagnosticWithParameters2Renderer<A : Any, B : Any>(
+class FirDiagnosticWithParameters2Renderer<A, B>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
     private val rendererForB: DiagnosticParameterRenderer<B>?,
 ) : AbstractFirDiagnosticWithParametersRenderer<FirDiagnosticWithParameters2<*, A, B>>(message) {
-    override fun renderParameters(diagnostic: FirDiagnosticWithParameters2<*, A, B>): Array<out Any> {
+    override fun renderParameters(diagnostic: FirDiagnosticWithParameters2<*, A, B>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a, diagnostic.b)
         return arrayOf(
             renderParameter(diagnostic.a, rendererForA, context),
@@ -45,13 +45,13 @@ class FirDiagnosticWithParameters2Renderer<A : Any, B : Any>(
     }
 }
 
-class FirDiagnosticWithParameters3Renderer<A : Any, B : Any, C : Any>(
+class FirDiagnosticWithParameters3Renderer<A, B, C>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
     private val rendererForB: DiagnosticParameterRenderer<B>?,
     private val rendererForC: DiagnosticParameterRenderer<C>?,
 ) : AbstractFirDiagnosticWithParametersRenderer<FirDiagnosticWithParameters3<*, A, B, C>>(message) {
-    override fun renderParameters(diagnostic: FirDiagnosticWithParameters3<*, A, B, C>): Array<out Any> {
+    override fun renderParameters(diagnostic: FirDiagnosticWithParameters3<*, A, B, C>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a, diagnostic.b, diagnostic.c)
         return arrayOf(
             renderParameter(diagnostic.a, rendererForA, context),
@@ -61,14 +61,14 @@ class FirDiagnosticWithParameters3Renderer<A : Any, B : Any, C : Any>(
     }
 }
 
-class FirDiagnosticWithParameters4Renderer<A : Any, B : Any, C : Any, D : Any>(
+class FirDiagnosticWithParameters4Renderer<A, B, C, D>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
     private val rendererForB: DiagnosticParameterRenderer<B>?,
     private val rendererForC: DiagnosticParameterRenderer<C>?,
     private val rendererForD: DiagnosticParameterRenderer<D>?,
 ) : AbstractFirDiagnosticWithParametersRenderer<FirDiagnosticWithParameters4<*, A, B, C, D>>(message) {
-    override fun renderParameters(diagnostic: FirDiagnosticWithParameters4<*, A, B, C, D>): Array<out Any> {
+    override fun renderParameters(diagnostic: FirDiagnosticWithParameters4<*, A, B, C, D>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a, diagnostic.b, diagnostic.c)
         return arrayOf(
             renderParameter(diagnostic.a, rendererForA, context),
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
index 118bdd56832..7b65f23e562 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirDiagnosticRenderers.kt
@@ -38,7 +38,7 @@ object FirDiagnosticRenderers {
         }
     }
 
-    val TO_STRING = Renderer { element: Any ->
+    val TO_STRING = Renderer { element: Any? ->
         element.toString()
     }
 
@@ -109,7 +109,7 @@ object FirDiagnosticRenderers {
         }
     }
 
-    val NOT_RENDERED = Renderer<Any> {
+    val NOT_RENDERED = Renderer<Any?> {
         ""
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DiagnosticRendererUtil.kt b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DiagnosticRendererUtil.kt
index 6f54ec927bc..d8817d254fa 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DiagnosticRendererUtil.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DiagnosticRendererUtil.kt
@@ -20,7 +20,7 @@ import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptorWithTypeParameters
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
 
-fun <P : Any> renderParameter(parameter: P, renderer: DiagnosticParameterRenderer<P>?, context: RenderingContext): Any =
+fun <P> renderParameter(parameter: P, renderer: DiagnosticParameterRenderer<P>?, context: RenderingContext): Any? =
     renderer?.render(parameter, context) ?: parameter
 
 fun ClassifierDescriptorWithTypeParameters.renderKindWithName(): String =
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/diagnosticsWithParameterRenderers.kt b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/diagnosticsWithParameterRenderers.kt
index df5f3da0de0..adc9d920afa 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/diagnosticsWithParameterRenderers.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/diagnosticsWithParameterRenderers.kt
@@ -27,29 +27,29 @@ abstract class AbstractDiagnosticWithParametersRenderer<in D : UnboundDiagnostic
         return messageFormat.format(renderParameters(diagnostic))
     }
 
-    abstract fun renderParameters(diagnostic: D): Array<out Any>
+    abstract fun renderParameters(diagnostic: D): Array<out Any?>
 
 }
 
 
-class DiagnosticWithParameters1Renderer<A : Any>(
+class DiagnosticWithParameters1Renderer<A>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?
 ) : AbstractDiagnosticWithParametersRenderer<DiagnosticWithParameters1<*, A>>(message) {
 
-    override fun renderParameters(diagnostic: DiagnosticWithParameters1<*, A>): Array<out Any> {
+    override fun renderParameters(diagnostic: DiagnosticWithParameters1<*, A>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a)
         return arrayOf(renderParameter(diagnostic.a, rendererForA, context))
     }
 }
 
-class DiagnosticWithParameters2Renderer<A : Any, B : Any>(
+class DiagnosticWithParameters2Renderer<A, B>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
     private val rendererForB: DiagnosticParameterRenderer<B>?
 ) : AbstractDiagnosticWithParametersRenderer<DiagnosticWithParameters2<*, A, B>>(message) {
 
-    override fun renderParameters(diagnostic: DiagnosticWithParameters2<*, A, B>): Array<out Any> {
+    override fun renderParameters(diagnostic: DiagnosticWithParameters2<*, A, B>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a, diagnostic.b)
         return arrayOf(
             renderParameter(diagnostic.a, rendererForA, context),
@@ -58,14 +58,14 @@ class DiagnosticWithParameters2Renderer<A : Any, B : Any>(
     }
 }
 
-class DiagnosticWithParameters3Renderer<A : Any, B : Any, C : Any>(
+class DiagnosticWithParameters3Renderer<A, B, C>(
     message: String,
     private val rendererForA: DiagnosticParameterRenderer<A>?,
     private val rendererForB: DiagnosticParameterRenderer<B>?,
     private val rendererForC: DiagnosticParameterRenderer<C>?
 ) : AbstractDiagnosticWithParametersRenderer<DiagnosticWithParameters3<*, A, B, C>>(message) {
 
-    override fun renderParameters(diagnostic: DiagnosticWithParameters3<*, A, B, C>): Array<out Any> {
+    override fun renderParameters(diagnostic: DiagnosticWithParameters3<*, A, B, C>): Array<out Any?> {
         val context = RenderingContext.of(diagnostic.a, diagnostic.b, diagnostic.c)
         return arrayOf(
             renderParameter(diagnostic.a, rendererForA, context),
diff --git a/compiler/test-infrastructure-utils/tests/org/jetbrains/kotlin/codeMetaInfo/renderConfigurations/DiagnosticCodeMetaInfoRenderConfiguration.kt b/compiler/test-infrastructure-utils/tests/org/jetbrains/kotlin/codeMetaInfo/renderConfigurations/DiagnosticCodeMetaInfoRenderConfiguration.kt
index 57b366af3e8..1196dec4749 100644
--- a/compiler/test-infrastructure-utils/tests/org/jetbrains/kotlin/codeMetaInfo/renderConfigurations/DiagnosticCodeMetaInfoRenderConfiguration.kt
+++ b/compiler/test-infrastructure-utils/tests/org/jetbrains/kotlin/codeMetaInfo/renderConfigurations/DiagnosticCodeMetaInfoRenderConfiguration.kt
@@ -38,7 +38,7 @@ open class DiagnosticCodeMetaInfoRenderConfiguration(
             else -> DefaultErrorMessages.getRendererForDiagnostic(codeMetaInfo.diagnostic)
         }
         if (renderer is AbstractDiagnosticWithParametersRenderer) {
-            renderer.renderParameters(codeMetaInfo.diagnostic).mapTo(params, Any::toString)
+            renderer.renderParameters(codeMetaInfo.diagnostic).mapTo(params, Any?::toString)
         }
         if (renderSeverity)
             params.add("severity='${codeMetaInfo.diagnostic.severity}'")
diff --git a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostics/FirIdeDiagnosticReporter.kt b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostics/FirIdeDiagnosticReporter.kt
index 5e006d29b4b..41b62bf311d 100644
--- a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostics/FirIdeDiagnosticReporter.kt
+++ b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostics/FirIdeDiagnosticReporter.kt
@@ -41,28 +41,28 @@ private fun FirLightDiagnostic.toPsiDiagnostic(): FirPsiDiagnostic<*> {
             psiSourceElement,
             a,
             severity,
-            factory as FirDiagnosticFactory1<PsiElement, Any>
+            factory as FirDiagnosticFactory1<PsiElement, Any?>
         )
 
         is FirLightDiagnosticWithParameters2<*, *> -> FirPsiDiagnosticWithParameters2(
             psiSourceElement,
             a, b,
             severity,
-            factory as FirDiagnosticFactory2<PsiElement, Any, Any>
+            factory as FirDiagnosticFactory2<PsiElement, Any?, Any?>
         )
 
         is FirLightDiagnosticWithParameters3<*, *, *> -> FirPsiDiagnosticWithParameters3(
             psiSourceElement,
             a, b, c,
             severity,
-            factory as FirDiagnosticFactory3<PsiElement, Any, Any, Any>
+            factory as FirDiagnosticFactory3<PsiElement, Any?, Any?, Any?>
         )
 
         is FirLightDiagnosticWithParameters4<*, *, *, *> -> FirPsiDiagnosticWithParameters4(
             psiSourceElement,
             a, b, c, d,
             severity,
-            factory as FirDiagnosticFactory4<PsiElement, Any, Any, Any, Any>
+            factory as FirDiagnosticFactory4<PsiElement, Any?, Any?, Any?, Any?>
         )
         else -> error("Unknown diagnostic type ${this::class.simpleName}")
     }
diff --git a/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/HLDiagnosticConverter.kt b/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/HLDiagnosticConverter.kt
index 5b2ad83e52f..bfed3fbcd3f 100644
--- a/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/HLDiagnosticConverter.kt
+++ b/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/HLDiagnosticConverter.kt
@@ -73,16 +73,21 @@ object HLDiagnosticConverter {
 
 private object FirToKtConversionCreator {
     fun createConversion(type: KType): HLParameterConversion {
+        val nullable = type.isMarkedNullable
         val kClass = type.classifier as KClass<*>
         return tryMapAllowedType(kClass)
             ?: tryMapPsiElementType(type, kClass)
-            ?: tryMapFirTypeToKtType(kClass)
+            ?: tryMapFirTypeToKtType(kClass, nullable)
             ?: tryMapPlatformType(type, kClass)
             ?: error("Unsupported type $type, consider add corresponding mapping")
     }
 
-    private fun tryMapFirTypeToKtType(kClass: KClass<*>): HLParameterConversion? {
-        return typeMapping[kClass]
+    private fun tryMapFirTypeToKtType(kClass: KClass<*>, nullable: Boolean): HLParameterConversion? {
+        return if (nullable) {
+            nullableTypeMapping[kClass] ?: typeMapping[kClass]
+        } else {
+            typeMapping[kClass]
+        }
     }
 
     private fun tryMapAllowedType(kClass: KClass<*>): HLParameterConversion? {
@@ -116,6 +121,17 @@ private object FirToKtConversionCreator {
         return null
     }
 
+    private val nullableTypeMapping: Map<KClass<*>, HLFunctionCallConversion> = mapOf(
+        FirExpression::class to HLFunctionCallConversion(
+            "{0}?.source?.psi as? KtExpression",
+            KtExpression::class.createType(nullable = true),
+            importsToAdd = listOf(
+                "org.jetbrains.kotlin.psi.KtExpression",
+                "org.jetbrains.kotlin.fir.psi"
+            )
+        ),
+    )
+
     private val typeMapping: Map<KClass<*>, HLFunctionCallConversion> = mapOf(
         AbstractFirBasedSymbol::class to HLFunctionCallConversion(
             "firSymbolBuilder.buildSymbol({0}.fir as FirDeclaration)",
diff --git a/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/generatorUtils.kt b/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/generatorUtils.kt
index aff7a760e49..0de1bab2c52 100644
--- a/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/generatorUtils.kt
+++ b/idea/idea-frontend-fir/idea-frontend-fir-generator/src/org/jetbrains/kotlin/idea/frontend/api/fir/generator/generatorUtils.kt
@@ -11,13 +11,14 @@ import kotlin.reflect.KType
 
 internal fun SmartPrinter.printTypeWithShortNames(type: KType) {
     fun typeConversion(type: KType): String {
+        val nullableSuffix = if (type.isMarkedNullable) "?" else ""
         val simpleName = (type.classifier as KClass<*>).simpleName!!
-        return if (type.arguments.isEmpty()) simpleName
+        return if (type.arguments.isEmpty()) simpleName + nullableSuffix
         else simpleName + type.arguments.joinToString(separator = ", ", prefix = "<", postfix = ">") {
             when (val typeArgument = it.type) {
                 null -> "*"
                 else -> typeConversion(typeArgument)
-            }
+            } + nullableSuffix
         }
     }
     print(typeConversion(type))
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtDiagnosticConverter.kt b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtDiagnosticConverter.kt
index 476802d01c5..8cb7917b176 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtDiagnosticConverter.kt
+++ b/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtDiagnosticConverter.kt
@@ -15,19 +15,19 @@ internal fun interface KtFirDiagnostic0Creator : KtFirDiagnosticCreator {
     fun KtFirAnalysisSession.create(diagnostic: FirSimpleDiagnostic<*>): KtFirDiagnostic<*>
 }
 
-internal fun interface KtFirDiagnostic1Creator<A : Any> : KtFirDiagnosticCreator {
+internal fun interface KtFirDiagnostic1Creator<A> : KtFirDiagnosticCreator {
     fun KtFirAnalysisSession.create(diagnostic: FirDiagnosticWithParameters1<*, A>): KtFirDiagnostic<*>
 }
 
-internal fun interface KtFirDiagnostic2Creator<A : Any, B : Any> : KtFirDiagnosticCreator {
+internal fun interface KtFirDiagnostic2Creator<A, B> : KtFirDiagnosticCreator {
     fun KtFirAnalysisSession.create(diagnostic: FirDiagnosticWithParameters2<*, A, B>): KtFirDiagnostic<*>
 }
 
-internal fun interface KtFirDiagnostic3Creator<A : Any, B : Any, C : Any> : KtFirDiagnosticCreator {
+internal fun interface KtFirDiagnostic3Creator<A, B, C> : KtFirDiagnosticCreator {
     fun KtFirAnalysisSession.create(diagnostic: FirDiagnosticWithParameters3<*, A, B, C>): KtFirDiagnostic<*>
 }
 
-internal fun interface KtFirDiagnostic4Creator<A : Any, B : Any, C : Any, D : Any> : KtFirDiagnosticCreator {
+internal fun interface KtFirDiagnostic4Creator<A, B, C, D> : KtFirDiagnosticCreator {
     fun KtFirAnalysisSession.create(diagnostic: FirDiagnosticWithParameters4<*, A, B, C, D>): KtFirDiagnostic<*>
 }
 
@@ -42,17 +42,17 @@ internal class KtDiagnosticConverter(private val conversions: Map<AbstractFirDia
                 is KtFirDiagnostic0Creator -> with(creator) {
                     create(diagnostic as FirSimpleDiagnostic<*>)
                 }
-                is KtFirDiagnostic1Creator<*> -> with(creator as KtFirDiagnostic1Creator<Any>) {
-                    create(diagnostic as FirDiagnosticWithParameters1<FirSourceElement, Any>)
+                is KtFirDiagnostic1Creator<*> -> with(creator as KtFirDiagnostic1Creator<Any?>) {
+                    create(diagnostic as FirDiagnosticWithParameters1<FirSourceElement, Any?>)
                 }
-                is KtFirDiagnostic2Creator<*, *> -> with(creator as KtFirDiagnostic2Creator<Any, Any>) {
-                    create(diagnostic as FirDiagnosticWithParameters2<FirSourceElement, Any, Any>)
+                is KtFirDiagnostic2Creator<*, *> -> with(creator as KtFirDiagnostic2Creator<Any?, Any?>) {
+                    create(diagnostic as FirDiagnosticWithParameters2<FirSourceElement, Any?, Any?>)
                 }
-                is KtFirDiagnostic3Creator<*, *, *> -> with(creator as KtFirDiagnostic3Creator<Any, Any, Any>) {
-                    create(diagnostic as FirDiagnosticWithParameters3<FirSourceElement, Any, Any, Any>)
+                is KtFirDiagnostic3Creator<*, *, *> -> with(creator as KtFirDiagnostic3Creator<Any?, Any?, Any?>) {
+                    create(diagnostic as FirDiagnosticWithParameters3<FirSourceElement, Any?, Any?, Any?>)
                 }
-                is KtFirDiagnostic4Creator<*, *, *, *> -> with(creator as KtFirDiagnostic4Creator<Any, Any, Any, Any>) {
-                    create(diagnostic as FirDiagnosticWithParameters4<FirSourceElement, Any, Any, Any, Any>)
+                is KtFirDiagnostic4Creator<*, *, *, *> -> with(creator as KtFirDiagnostic4Creator<Any?, Any?, Any?, Any?>) {
+                    create(diagnostic as FirDiagnosticWithParameters4<FirSourceElement, Any?, Any?, Any?, Any?>)
                 }
                 else -> error("Invalid KtFirDiagnosticCreator ${creator::class.simpleName}")
             }
@@ -67,19 +67,19 @@ internal class KtDiagnosticConverterBuilder private constructor() {
         conversions[diagnostic] = creator
     }
 
-    fun <A : Any> add(diagnostic: FirDiagnosticFactory1<*, A>, creator: KtFirDiagnostic1Creator<A>) {
+    fun <A> add(diagnostic: FirDiagnosticFactory1<*, A>, creator: KtFirDiagnostic1Creator<A>) {
         conversions[diagnostic] = creator
     }
 
-    fun <A : Any, B : Any> add(diagnostic: FirDiagnosticFactory2<*, A, B>, creator: KtFirDiagnostic2Creator<A, B>) {
+    fun <A, B> add(diagnostic: FirDiagnosticFactory2<*, A, B>, creator: KtFirDiagnostic2Creator<A, B>) {
         conversions[diagnostic] = creator
     }
 
-    fun <A : Any, B : Any, C : Any> add(diagnostic: FirDiagnosticFactory3<*, A, B, C>, creator: KtFirDiagnostic3Creator<A, B, C>) {
+    fun <A, B, C> add(diagnostic: FirDiagnosticFactory3<*, A, B, C>, creator: KtFirDiagnostic3Creator<A, B, C>) {
         conversions[diagnostic] = creator
     }
 
-    fun <A : Any, B : Any, C : Any, D : Any> add(diagnostic: FirDiagnosticFactory4<*, A, B, C, D>, creator: KtFirDiagnostic4Creator<A, B, C, D>) {
+    fun <A, B, C, D> add(diagnostic: FirDiagnosticFactory4<*, A, B, C, D>, creator: KtFirDiagnostic4Creator<A, B, C, D>) {
         conversions[diagnostic] = creator
     }