diff --git a/compiler/testData/ir/irText/classes/kt45934.fir.ir.txt b/compiler/testData/ir/irText/classes/kt45934.fir.ir.txt
index e30b4b18b20..5d737dda6fe 100644
--- a/compiler/testData/ir/irText/classes/kt45934.fir.ir.txt
+++ b/compiler/testData/ir/irText/classes/kt45934.fir.ir.txt
@@ -6,14 +6,14 @@ FILE fqName:<root> fileName:/kt45934.kt
       BLOCK_BODY
         DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
         INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:C modality:FINAL visibility:public superTypes:[<root>.I]'
-    FUN DELEGATED_MEMBER name:foo visibility:public modality:OPEN <C> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] C of <root>.C.foo?>?
+    FUN DELEGATED_MEMBER name:foo visibility:public modality:OPEN <C> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] C of <root>.C.foo?>?
       overridden:
-        public abstract fun foo <C> (): @[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] C of <root>.I.foo?>? declared in <root>.I
+        public abstract fun foo <C> (): @[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] C of <root>.I.foo?>? declared in <root>.I
       TYPE_PARAMETER name:C index:0 variance: superTypes:[@[FlexibleNullability] kotlin.Any?] reified:false
       $this: VALUE_PARAMETER name:<this> type:<root>.C
       BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public open fun foo <C> (): @[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] C of <root>.C.foo?>? declared in <root>.C'
-          CALL 'public open fun foo (): @[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] kotlin.String?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] C of <root>.C.foo?>? origin=null
+        RETURN type=kotlin.Nothing from='public open fun foo <C> (): @[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] C of <root>.C.foo?>? declared in <root>.C'
+          CALL 'public open fun foo (): @[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] kotlin.String?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] C of <root>.C.foo?>? origin=null
             $this: GET_FIELD 'FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]' type=<root>.J origin=null
               receiver: GET_VAR '<this>: <root>.C declared in <root>.C.foo' type=<root>.C origin=null
     FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]
diff --git a/compiler/testData/ir/irText/expressions/genericPropertyRef.fir.ir.txt b/compiler/testData/ir/irText/expressions/genericPropertyRef.fir.ir.txt
index a339a5173a5..f2b491368c1 100644
--- a/compiler/testData/ir/irText/expressions/genericPropertyRef.fir.ir.txt
+++ b/compiler/testData/ir/irText/expressions/genericPropertyRef.fir.ir.txt
@@ -172,20 +172,20 @@ FILE fqName:<root> fileName:/genericPropertyRef.kt
       BLOCK_BODY
         RETURN type=kotlin.Nothing from='public final fun <get-bar> <T> (): T of <root>.<get-bar> declared in <root>'
           GET_VAR '<this>: T of <root>.<get-bar> declared in <root>.<get-bar>' type=T of <root>.<get-bar> origin=null
-    FUN name:<set-bar> visibility:public modality:FINAL <T> ($receiver:T of <root>.<set-bar>, value:T of <root>.<get-bar>) returnType:kotlin.Unit
+    FUN name:<set-bar> visibility:public modality:FINAL <T> ($receiver:T of <root>.<set-bar>, value:T of <root>.<set-bar>) returnType:kotlin.Unit
       correspondingProperty: PROPERTY name:bar visibility:public modality:FINAL [var]
       TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?] reified:false
       $receiver: VALUE_PARAMETER name:<this> type:T of <root>.<set-bar>
-      VALUE_PARAMETER name:value index:0 type:T of <root>.<get-bar>
+      VALUE_PARAMETER name:value index:0 type:T of <root>.<set-bar>
       BLOCK_BODY
         CALL 'public final fun <set-recivier> (<set-?>: kotlin.Any?): kotlin.Unit declared in <root>' type=kotlin.Unit origin=EQ
           <set-?>: GET_VAR '<this>: T of <root>.<set-bar> declared in <root>.<set-bar>' type=T of <root>.<set-bar> origin=null
         CALL 'public final fun <set-value2> (<set-?>: kotlin.Any?): kotlin.Unit declared in <root>' type=kotlin.Unit origin=EQ
-          <set-?>: GET_VAR 'value: T of <root>.<get-bar> declared in <root>.<set-bar>' type=T of <root>.<get-bar> origin=null
+          <set-?>: GET_VAR 'value: T of <root>.<set-bar> declared in <root>.<set-bar>' type=T of <root>.<get-bar> origin=null
   PROPERTY name:barRef visibility:public modality:FINAL [val]
     FIELD PROPERTY_BACKING_FIELD name:barRef type:kotlin.reflect.KMutableProperty1<kotlin.String?, kotlin.String?> visibility:private [final,static]
       EXPRESSION_BODY
-        PROPERTY_REFERENCE 'public final bar: T of <root>.<get-bar> [var]' field=null getter='public final fun <get-bar> <T> (): T of <root>.<get-bar> declared in <root>' setter='public final fun <set-bar> <T> (value: T of <root>.<get-bar>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty1<kotlin.String?, kotlin.String?> origin=null
+        PROPERTY_REFERENCE 'public final bar: T of <root>.<get-bar> [var]' field=null getter='public final fun <get-bar> <T> (): T of <root>.<get-bar> declared in <root>' setter='public final fun <set-bar> <T> (value: T of <root>.<set-bar>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty1<kotlin.String?, kotlin.String?> origin=null
           <1>: kotlin.String?
     FUN DEFAULT_PROPERTY_ACCESSOR name:<get-barRef> visibility:public modality:FINAL <> () returnType:kotlin.reflect.KMutableProperty1<kotlin.String?, kotlin.String?>
       correspondingProperty: PROPERTY name:barRef visibility:public modality:FINAL [val]
diff --git a/compiler/testData/ir/irText/firProblems/AbstractMutableMap.fir.ir.txt b/compiler/testData/ir/irText/firProblems/AbstractMutableMap.fir.ir.txt
index bda7ce0cd82..7bcf65f6e00 100644
--- a/compiler/testData/ir/irText/firProblems/AbstractMutableMap.fir.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/AbstractMutableMap.fir.ir.txt
@@ -20,11 +20,11 @@ FILE fqName:<root> fileName:/AbstractMutableMap.kt
           CONST Null type=kotlin.Nothing? value=null
     PROPERTY name:entries visibility:public modality:FINAL [val]
       overridden:
-        public abstract entries: @[FlexibleNullability] kotlin.collections.Set<@[FlexibleNullability] kotlin.collections.Map.Entry<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?, @[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>?>? [fake_override,val]
+        public abstract entries: @[FlexibleNullability] kotlin.collections.MutableSet<@[FlexibleNullability] kotlin.collections.MutableMap.MutableEntry<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?, @[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>?>? [fake_override,val]
       FUN name:<get-entries> visibility:public modality:FINAL <> ($this:<root>.MyMap<K of <root>.MyMap, V of <root>.MyMap>) returnType:kotlin.collections.MutableSet<kotlin.collections.MutableMap.MutableEntry<K of <root>.MyMap, V of <root>.MyMap>>
         correspondingProperty: PROPERTY name:entries visibility:public modality:FINAL [val]
         overridden:
-          public abstract fun <get-entries> (): @[FlexibleNullability] kotlin.collections.Set<@[FlexibleNullability] kotlin.collections.Map.Entry<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?, @[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
+          public abstract fun <get-entries> (): @[FlexibleNullability] kotlin.collections.MutableSet<@[FlexibleNullability] kotlin.collections.MutableMap.MutableEntry<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?, @[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
         $this: VALUE_PARAMETER name:<this> type:<root>.MyMap<K of <root>.MyMap, V of <root>.MyMap>
         BLOCK_BODY
           RETURN type=kotlin.Nothing from='public final fun <get-entries> (): kotlin.collections.MutableSet<kotlin.collections.MutableMap.MutableEntry<K of <root>.MyMap, V of <root>.MyMap>> declared in <root>.MyMap'
@@ -55,19 +55,19 @@ FILE fqName:<root> fileName:/AbstractMutableMap.kt
       VALUE_PARAMETER name:value index:1 type:V of <root>.MyMap
     PROPERTY FAKE_OVERRIDE name:keys visibility:public modality:OPEN [fake_override,val]
       overridden:
-        public open keys: @[FlexibleNullability] kotlin.collections.Set<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?>? [fake_override,val]
-      FUN FAKE_OVERRIDE name:<get-keys> visibility:public modality:OPEN <> ($this:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>) returnType:@[FlexibleNullability] kotlin.collections.Set<@[FlexibleNullability] K of <root>.MyMap?>? [fake_override]
+        public open keys: @[FlexibleNullability] kotlin.collections.MutableSet<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?>? [fake_override,val]
+      FUN FAKE_OVERRIDE name:<get-keys> visibility:public modality:OPEN <> ($this:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>) returnType:@[FlexibleNullability] kotlin.collections.MutableSet<@[FlexibleNullability] K of <root>.MyMap?>? [fake_override]
         correspondingProperty: PROPERTY FAKE_OVERRIDE name:keys visibility:public modality:OPEN [fake_override,val]
         overridden:
-          public open fun <get-keys> (): @[FlexibleNullability] kotlin.collections.Set<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
+          public open fun <get-keys> (): @[FlexibleNullability] kotlin.collections.MutableSet<@[FlexibleNullability] K of kotlin.collections.AbstractMutableMap?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
         $this: VALUE_PARAMETER name:<this> type:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>
     PROPERTY FAKE_OVERRIDE name:values visibility:public modality:OPEN [fake_override,val]
       overridden:
-        public open values: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>? [fake_override,val]
-      FUN FAKE_OVERRIDE name:<get-values> visibility:public modality:OPEN <> ($this:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>) returnType:@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] V of <root>.MyMap?>? [fake_override]
+        public open values: @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>? [fake_override,val]
+      FUN FAKE_OVERRIDE name:<get-values> visibility:public modality:OPEN <> ($this:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>) returnType:@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] V of <root>.MyMap?>? [fake_override]
         correspondingProperty: PROPERTY FAKE_OVERRIDE name:values visibility:public modality:OPEN [fake_override,val]
         overridden:
-          public open fun <get-values> (): @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
+          public open fun <get-values> (): @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] V of kotlin.collections.AbstractMutableMap?>? [fake_override] declared in kotlin.collections.AbstractMutableMap
         $this: VALUE_PARAMETER name:<this> type:java.util.AbstractMap<K of java.util.AbstractMap, V of java.util.AbstractMap>
     FUN FAKE_OVERRIDE name:replaceAll visibility:public modality:OPEN <> ($this:kotlin.collections.MutableMap<K of kotlin.collections.MutableMap, V of kotlin.collections.MutableMap>, p0:@[EnhancedNullability] java.util.function.BiFunction<in @[EnhancedNullability] K of <root>.MyMap, in @[EnhancedNullability] V of <root>.MyMap, out @[EnhancedNullability] V of <root>.MyMap>) returnType:kotlin.Unit [fake_override]
       overridden:
diff --git a/compiler/testData/ir/irText/firProblems/AllCandidates.fir.ir.txt b/compiler/testData/ir/irText/firProblems/AllCandidates.fir.ir.txt
index c3df05b9331..5f97584df8c 100644
--- a/compiler/testData/ir/irText/firProblems/AllCandidates.fir.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/AllCandidates.fir.ir.txt
@@ -63,7 +63,7 @@ FILE fqName:<root> fileName:/AllCandidates.kt
             FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> ($receiver:@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?) returnType:kotlin.Unit
               $receiver: VALUE_PARAMETER name:$this$apply type:@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>?
               BLOCK_BODY
-                CALL 'public open fun setAllCandidates (allCandidates: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] <root>.ResolvedCall<@[FlexibleNullability] D of <root>.OverloadResolutionResultsImpl?>?>?): kotlin.Unit declared in <root>.OverloadResolutionResultsImpl' type=kotlin.Unit origin=EQ
+                CALL 'public open fun setAllCandidates (allCandidates: @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] <root>.ResolvedCall<@[FlexibleNullability] D of <root>.OverloadResolutionResultsImpl?>?>?): kotlin.Unit declared in <root>.OverloadResolutionResultsImpl' type=kotlin.Unit origin=EQ
                   $this: GET_VAR '$this$apply: @[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? declared in <root>.allCandidatesResult.<anonymous>' type=@[FlexibleNullability] <root>.OverloadResolutionResultsImpl<@[FlexibleNullability] A of <root>.allCandidatesResult?>? origin=null
                   allCandidates: CALL 'public final fun map <T, R> (transform: kotlin.Function1<T of kotlin.collections.CollectionsKt.map, R of kotlin.collections.CollectionsKt.map>): kotlin.collections.List<R of kotlin.collections.CollectionsKt.map> [inline] declared in kotlin.collections.CollectionsKt' type=kotlin.collections.List<<root>.ResolvedCall<A of <root>.allCandidatesResult>> origin=null
                     <T>: <root>.MyCandidate
diff --git a/compiler/testData/ir/irText/firProblems/SyntheticSetterType.fir.ir.txt b/compiler/testData/ir/irText/firProblems/SyntheticSetterType.fir.ir.txt
index 89f8031f8aa..bd2fffebf24 100644
--- a/compiler/testData/ir/irText/firProblems/SyntheticSetterType.fir.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/SyntheticSetterType.fir.ir.txt
@@ -2,7 +2,7 @@ FILE fqName:<root> fileName:/SyntheticSetterType.kt
   FUN name:foo visibility:public modality:FINAL <> (descriptor:<root>.PropertyDescriptorImpl) returnType:kotlin.Unit
     VALUE_PARAMETER name:descriptor index:0 type:<root>.PropertyDescriptorImpl
     BLOCK_BODY
-      CALL 'public open fun setOverriddenDescriptors (overriddenDescriptors: @[EnhancedNullability] kotlin.collections.Collection<out @[FlexibleNullability] <root>.CallableMemberDescriptor?>): kotlin.Unit declared in <root>.PropertyDescriptorImpl' type=kotlin.Unit origin=EQ
+      CALL 'public open fun setOverriddenDescriptors (overriddenDescriptors: @[EnhancedNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] <root>.CallableMemberDescriptor?>): kotlin.Unit declared in <root>.PropertyDescriptorImpl' type=kotlin.Unit origin=EQ
         $this: GET_VAR 'descriptor: <root>.PropertyDescriptorImpl declared in <root>.foo' type=<root>.PropertyDescriptorImpl origin=null
         overriddenDescriptors: CALL 'public final fun emptyList <T> (): kotlin.collections.List<T of kotlin.collections.CollectionsKt.emptyList> declared in kotlin.collections.CollectionsKt' type=kotlin.collections.List<@[FlexibleNullability] <root>.PropertyDescriptor?> origin=null
           <T>: @[FlexibleNullability] <root>.PropertyDescriptor?
diff --git a/compiler/testData/ir/irText/regressions/integerCoercionToT.fir.ir.txt b/compiler/testData/ir/irText/regressions/integerCoercionToT.fir.ir.txt
index 580ad8571e1..0643a387bc8 100644
--- a/compiler/testData/ir/irText/regressions/integerCoercionToT.fir.ir.txt
+++ b/compiler/testData/ir/irText/regressions/integerCoercionToT.fir.ir.txt
@@ -49,11 +49,11 @@ FILE fqName:<root> fileName:/integerCoercionToT.kt
       BLOCK_BODY
         RETURN type=kotlin.Nothing from='public final fun <get-value> <T_INT> (): T_INT of <root>.<get-value> declared in <root>'
           CALL 'public final fun TODO (): kotlin.Nothing [inline] declared in kotlin.StandardKt' type=kotlin.Nothing origin=null
-    FUN name:<set-value> visibility:public modality:FINAL <T_INT> ($receiver:<root>.CInt32VarX<T_INT of <root>.<set-value>>, value:T_INT of <root>.<get-value>) returnType:kotlin.Unit
+    FUN name:<set-value> visibility:public modality:FINAL <T_INT> ($receiver:<root>.CInt32VarX<T_INT of <root>.<set-value>>, value:T_INT of <root>.<set-value>) returnType:kotlin.Unit
       correspondingProperty: PROPERTY name:value visibility:public modality:FINAL [var]
       TYPE_PARAMETER name:T_INT index:0 variance: superTypes:[kotlin.Int] reified:false
       $receiver: VALUE_PARAMETER name:<this> type:<root>.CInt32VarX<T_INT of <root>.<set-value>>
-      VALUE_PARAMETER name:value index:0 type:T_INT of <root>.<get-value>
+      VALUE_PARAMETER name:value index:0 type:T_INT of <root>.<set-value>
       BLOCK_BODY
   CLASS CLASS name:IdType modality:FINAL visibility:public superTypes:[<root>.CPointed]
     $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.IdType
@@ -90,7 +90,7 @@ FILE fqName:<root> fileName:/integerCoercionToT.kt
     VALUE_PARAMETER name:value index:0 type:<root>.IdType
     VALUE_PARAMETER name:cv index:1 type:<root>.CInt32VarX<kotlin.Int>
     BLOCK_BODY
-      CALL 'public final fun <set-value> <T_INT> (value: T_INT of <root>.<get-value>): kotlin.Unit declared in <root>' type=kotlin.Unit origin=EQ
+      CALL 'public final fun <set-value> <T_INT> (value: T_INT of <root>.<set-value>): kotlin.Unit declared in <root>' type=kotlin.Unit origin=EQ
         <T_INT>: kotlin.Int
         $receiver: GET_VAR 'cv: <root>.CInt32VarX<kotlin.Int> declared in <root>.foo' type=<root>.CInt32VarX<kotlin.Int> origin=null
         value: CALL 'public final fun <get-value> (): kotlin.Int declared in <root>.IdType' type=kotlin.Int origin=GET_PROPERTY
diff --git a/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.ir.txt b/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.ir.txt
index 65828931a81..806758b6525 100644
--- a/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.ir.txt
+++ b/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.ir.txt
@@ -13,7 +13,7 @@ FILE fqName:<root> fileName:/typeParametersInImplicitCast.kt
               VALUE_PARAMETER name:it index:0 type:kotlin.collections.List<T of <root>.problematic>
               BLOCK_BODY
                 RETURN type=kotlin.Nothing from='local final fun <anonymous> (it: kotlin.collections.List<T of <root>.problematic>): kotlin.collections.Iterable<@[FlexibleNullability] T of <root>.problematic?> declared in <root>.problematic'
-                  TYPE_OP type=kotlin.collections.List<@[FlexibleNullability] T of <root>.problematic?> origin=IMPLICIT_NOTNULL typeOperand=kotlin.collections.List<@[FlexibleNullability] T of <root>.problematic?>
-                    CALL 'public/*package*/ open fun id <T> (v: @[FlexibleNullability] kotlin.collections.List<@[FlexibleNullability] T of <root>.ListId.id?>?): @[EnhancedNullability] kotlin.collections.List<@[FlexibleNullability] T of <root>.ListId.id?> declared in <root>.ListId' type=@[EnhancedNullability] kotlin.collections.List<@[FlexibleNullability] T of <root>.problematic?> origin=null
+                  TYPE_OP type=kotlin.collections.MutableList<@[FlexibleNullability] T of <root>.problematic?> origin=IMPLICIT_NOTNULL typeOperand=kotlin.collections.MutableList<@[FlexibleNullability] T of <root>.problematic?>
+                    CALL 'public/*package*/ open fun id <T> (v: @[FlexibleNullability] kotlin.collections.MutableList<@[FlexibleNullability] T of <root>.ListId.id?>?): @[EnhancedNullability] kotlin.collections.MutableList<@[FlexibleNullability] T of <root>.ListId.id?> declared in <root>.ListId' type=@[EnhancedNullability] kotlin.collections.MutableList<@[FlexibleNullability] T of <root>.problematic?> origin=null
                       <T>: @[FlexibleNullability] T of <root>.problematic?
                       v: GET_VAR 'it: kotlin.collections.List<T of <root>.problematic> declared in <root>.problematic.<anonymous>' type=kotlin.collections.List<T of <root>.problematic> origin=null
diff --git a/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.kt.txt b/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.kt.txt
index 46c3209a98b..8d4129700a2 100644
--- a/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.kt.txt
+++ b/compiler/testData/ir/irText/regressions/typeParametersInImplicitCast.fir.kt.txt
@@ -1,6 +1,7 @@
 fun <T : Any?> problematic(lss: List<List<T>>): List<T> {
   return lss.flatMap<List<T>, @FlexibleNullability T?>(transform = local fun <anonymous>(it: List<T>): Iterable<@FlexibleNullability T?> {
-    return id<@FlexibleNullability T?>(v = it) /*!! List<@FlexibleNullability T?> */
+    return id<@FlexibleNullability T?>(v = it) /*!! MutableList<@FlexibleNullability T?> */
   }
 )
 }
+
diff --git a/compiler/testData/ir/irText/stubs/builtinMap.fir.ir.txt b/compiler/testData/ir/irText/stubs/builtinMap.fir.ir.txt
index dd396cc203b..cbfc9c5d4c6 100644
--- a/compiler/testData/ir/irText/stubs/builtinMap.fir.ir.txt
+++ b/compiler/testData/ir/irText/stubs/builtinMap.fir.ir.txt
@@ -18,7 +18,7 @@ FILE fqName:<root> fileName:/builtinMap.kt
             if: CONST Boolean type=kotlin.Boolean value=true
             then: CALL 'public final fun apply <T> (block: @[ExtensionFunctionType] kotlin.Function1<T of kotlin.StandardKt.apply, kotlin.Unit>): T of kotlin.StandardKt.apply [inline] declared in kotlin.StandardKt' type=java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> origin=null
               <T>: java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?>
-              $receiver: CONSTRUCTOR_CALL 'public constructor <init> (p0: @[FlexibleNullability] kotlin.collections.Map<out @[FlexibleNullability] K of java.util.LinkedHashMap?, out @[FlexibleNullability] V of java.util.LinkedHashMap?>?) declared in java.util.LinkedHashMap' type=java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> origin=null
+              $receiver: CONSTRUCTOR_CALL 'public constructor <init> (p0: @[FlexibleNullability] kotlin.collections.MutableMap<out @[FlexibleNullability] K of java.util.LinkedHashMap?, out @[FlexibleNullability] V of java.util.LinkedHashMap?>?) declared in java.util.LinkedHashMap' type=java.util.LinkedHashMap<@[FlexibleNullability] K1 of <root>.plus?, @[FlexibleNullability] V1 of <root>.plus?> origin=null
                 <class: K>: @[FlexibleNullability] K1 of <root>.plus?
                 <class: V>: @[FlexibleNullability] V1 of <root>.plus?
                 p0: GET_VAR '<this>: kotlin.collections.Map<out K1 of <root>.plus, V1 of <root>.plus> declared in <root>.plus' type=kotlin.collections.Map<out K1 of <root>.plus, V1 of <root>.plus> origin=null
diff --git a/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.ir.txt b/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.ir.txt
index a8e4ab00ea4..b538f763b15 100644
--- a/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.ir.txt
+++ b/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.ir.txt
@@ -48,23 +48,22 @@ FILE fqName:<root> fileName:/genericPropertyReferenceType.kt
         RETURN type=kotlin.Nothing from='public final fun <get-y> <T> (): T of <root>.<get-y> declared in <root>'
           CALL 'public final fun <get-x> (): T of <root>.C declared in <root>.C' type=T of <root>.<get-y> origin=GET_PROPERTY
             $this: GET_VAR '<this>: <root>.C<T of <root>.<get-y>> declared in <root>.<get-y>' type=<root>.C<T of <root>.<get-y>> origin=null
-    FUN name:<set-y> visibility:public modality:FINAL <T> ($receiver:<root>.C<T of <root>.<set-y>>, v:T of <root>.<get-y>) returnType:kotlin.Unit
+    FUN name:<set-y> visibility:public modality:FINAL <T> ($receiver:<root>.C<T of <root>.<set-y>>, v:T of <root>.<set-y>) returnType:kotlin.Unit
       correspondingProperty: PROPERTY name:y visibility:public modality:FINAL [var]
       TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?] reified:false
       $receiver: VALUE_PARAMETER name:<this> type:<root>.C<T of <root>.<set-y>>
-      VALUE_PARAMETER name:v index:0 type:T of <root>.<get-y>
+      VALUE_PARAMETER name:v index:0 type:T of <root>.<set-y>
       BLOCK_BODY
         CALL 'public final fun <set-x> (<set-?>: T of <root>.C): kotlin.Unit declared in <root>.C' type=kotlin.Unit origin=EQ
-          $this: TYPE_OP type=<root>.C<T of <root>.<get-y>> origin=IMPLICIT_CAST typeOperand=<root>.C<T of <root>.<get-y>>
-            GET_VAR '<this>: <root>.C<T of <root>.<set-y>> declared in <root>.<set-y>' type=<root>.C<T of <root>.<set-y>> origin=null
-          <set-?>: GET_VAR 'v: T of <root>.<get-y> declared in <root>.<set-y>' type=T of <root>.<get-y> origin=null
+          $this: GET_VAR '<this>: <root>.C<T of <root>.<set-y>> declared in <root>.<set-y>' type=<root>.C<T of <root>.<set-y>> origin=null
+          <set-?>: GET_VAR 'v: T of <root>.<set-y> declared in <root>.<set-y>' type=T of <root>.<get-y> origin=null
   FUN name:use visibility:public modality:FINAL <> (p:kotlin.reflect.KMutableProperty<kotlin.String>) returnType:kotlin.Unit
     VALUE_PARAMETER name:p index:0 type:kotlin.reflect.KMutableProperty<kotlin.String>
     BLOCK_BODY
   FUN name:test1 visibility:public modality:FINAL <> () returnType:kotlin.Unit
     BLOCK_BODY
       CALL 'public final fun use (p: kotlin.reflect.KMutableProperty<kotlin.String>): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
-        p: PROPERTY_REFERENCE 'public final y: T of <root>.<get-y> [var]' field=null getter='public final fun <get-y> <T> (): T of <root>.<get-y> declared in <root>' setter='public final fun <set-y> <T> (v: T of <root>.<get-y>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty0<kotlin.String> origin=null
+        p: PROPERTY_REFERENCE 'public final y: T of <root>.<get-y> [var]' field=null getter='public final fun <get-y> <T> (): T of <root>.<get-y> declared in <root>' setter='public final fun <set-y> <T> (v: T of <root>.<set-y>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty0<kotlin.String> origin=null
           <1>: kotlin.String
           $receiver: CONSTRUCTOR_CALL 'public constructor <init> (x: T of <root>.C) [primary] declared in <root>.C' type=<root>.C<kotlin.String> origin=null
             <class: T>: kotlin.String
@@ -76,7 +75,7 @@ FILE fqName:<root> fileName:/genericPropertyReferenceType.kt
         TYPE_OP type=<root>.C<kotlin.String> origin=CAST typeOperand=<root>.C<kotlin.String>
           GET_VAR 'a: kotlin.Any declared in <root>.test2' type=kotlin.Any origin=null
       CALL 'public final fun use (p: kotlin.reflect.KMutableProperty<kotlin.String>): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
-        p: PROPERTY_REFERENCE 'public final y: T of <root>.<get-y> [var]' field=null getter='public final fun <get-y> <T> (): T of <root>.<get-y> declared in <root>' setter='public final fun <set-y> <T> (v: T of <root>.<get-y>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty0<kotlin.String> origin=null
+        p: PROPERTY_REFERENCE 'public final y: T of <root>.<get-y> [var]' field=null getter='public final fun <get-y> <T> (): T of <root>.<get-y> declared in <root>' setter='public final fun <set-y> <T> (v: T of <root>.<set-y>): kotlin.Unit declared in <root>' type=kotlin.reflect.KMutableProperty0<kotlin.String> origin=null
           <1>: kotlin.String
           $receiver: TYPE_OP type=<root>.C<kotlin.String> origin=IMPLICIT_CAST typeOperand=<root>.C<kotlin.String>
             GET_VAR 'a: kotlin.Any declared in <root>.test2' type=kotlin.Any origin=null
diff --git a/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.kt.txt b/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.kt.txt
index 22e24614d4c..19607410ad6 100644
--- a/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.kt.txt
+++ b/compiler/testData/ir/irText/types/genericPropertyReferenceType.fir.kt.txt
@@ -17,7 +17,7 @@ var <T : Any?> C<T>.y: T
     return <this>.<get-x>()
   }
   set(v: T) {
-    <this> /*as C<T> */.<set-x>(<set-?> = v)
+    <this>.<set-x>(<set-?> = v)
   }
 
 fun use(p: KMutableProperty<String>) {
@@ -31,3 +31,4 @@ fun test2(a: Any) {
   a as C<String> /*~> Unit */
   use(p = a /*as C<String> */::y/*<String>()*/)
 }
+
diff --git a/compiler/testData/ir/irText/types/javaWildcardType.fir.ir.txt b/compiler/testData/ir/irText/types/javaWildcardType.fir.ir.txt
index 6c20db48a40..280a8e99fd0 100644
--- a/compiler/testData/ir/irText/types/javaWildcardType.fir.ir.txt
+++ b/compiler/testData/ir/irText/types/javaWildcardType.fir.ir.txt
@@ -32,44 +32,44 @@ FILE fqName:<root> fileName:/javaWildcardType.kt
       BLOCK_BODY
         DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
         INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:C modality:FINAL visibility:public superTypes:[<root>.J; <root>.K]'
-    FUN DELEGATED_MEMBER name:jf1 visibility:public modality:OPEN <> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>?
+    FUN DELEGATED_MEMBER name:jf1 visibility:public modality:OPEN <> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>?
       overridden:
-        public abstract fun jf1 (): @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J
+        public abstract fun jf1 (): @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J
       $this: VALUE_PARAMETER name:<this> type:<root>.C
       BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public open fun jf1 (): @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C'
-          CALL 'public abstract fun jf1 (): @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? origin=null
+        RETURN type=kotlin.Nothing from='public open fun jf1 (): @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C'
+          CALL 'public abstract fun jf1 (): @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? origin=null
             $this: GET_FIELD 'FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]' type=<root>.J origin=null
               receiver: GET_VAR '<this>: <root>.C declared in <root>.C.jf1' type=<root>.C origin=null
-    FUN DELEGATED_MEMBER name:jf2 visibility:public modality:OPEN <> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>?
+    FUN DELEGATED_MEMBER name:jf2 visibility:public modality:OPEN <> ($this:<root>.C) returnType:@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>?
       overridden:
-        public abstract fun jf2 (): @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J
+        public abstract fun jf2 (): @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J
       $this: VALUE_PARAMETER name:<this> type:<root>.C
       BLOCK_BODY
-        RETURN type=kotlin.Nothing from='public open fun jf2 (): @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C'
-          CALL 'public abstract fun jf2 (): @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? origin=null
+        RETURN type=kotlin.Nothing from='public open fun jf2 (): @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C'
+          CALL 'public abstract fun jf2 (): @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? origin=null
             $this: GET_FIELD 'FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]' type=<root>.J origin=null
               receiver: GET_VAR '<this>: <root>.C declared in <root>.C.jf2' type=<root>.C origin=null
-    FUN DELEGATED_MEMBER name:jg1 visibility:public modality:OPEN <> ($this:<root>.C, c:@[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>?) returnType:kotlin.Unit
+    FUN DELEGATED_MEMBER name:jg1 visibility:public modality:OPEN <> ($this:<root>.C, c:@[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>?) returnType:kotlin.Unit
       overridden:
-        public abstract fun jg1 (c: @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J
+        public abstract fun jg1 (c: @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J
       $this: VALUE_PARAMETER name:<this> type:<root>.C
-      VALUE_PARAMETER name:c index:0 type:@[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>?
+      VALUE_PARAMETER name:c index:0 type:@[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>?
       BLOCK_BODY
-        CALL 'public abstract fun jg1 (c: @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J' type=kotlin.Unit origin=null
+        CALL 'public abstract fun jg1 (c: @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J' type=kotlin.Unit origin=null
           $this: GET_FIELD 'FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]' type=<root>.J origin=null
             receiver: GET_VAR '<this>: <root>.C declared in <root>.C.jg1' type=<root>.C origin=null
-          c: GET_VAR 'c: @[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C.jg1' type=@[FlexibleNullability] kotlin.collections.Collection<out @[FlexibleNullability] kotlin.CharSequence?>? origin=null
-    FUN DELEGATED_MEMBER name:jg2 visibility:public modality:OPEN <> ($this:<root>.C, c:@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>?) returnType:kotlin.Unit
+          c: GET_VAR 'c: @[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C.jg1' type=@[FlexibleNullability] kotlin.collections.MutableCollection<out @[FlexibleNullability] kotlin.CharSequence?>? origin=null
+    FUN DELEGATED_MEMBER name:jg2 visibility:public modality:OPEN <> ($this:<root>.C, c:@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>?) returnType:kotlin.Unit
       overridden:
-        public abstract fun jg2 (c: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J
+        public abstract fun jg2 (c: @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J
       $this: VALUE_PARAMETER name:<this> type:<root>.C
-      VALUE_PARAMETER name:c index:0 type:@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>?
+      VALUE_PARAMETER name:c index:0 type:@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>?
       BLOCK_BODY
-        CALL 'public abstract fun jg2 (c: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J' type=kotlin.Unit origin=null
+        CALL 'public abstract fun jg2 (c: @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>?): kotlin.Unit declared in <root>.J' type=kotlin.Unit origin=null
           $this: GET_FIELD 'FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]' type=<root>.J origin=null
             receiver: GET_VAR '<this>: <root>.C declared in <root>.C.jg2' type=<root>.C origin=null
-          c: GET_VAR 'c: @[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C.jg2' type=@[FlexibleNullability] kotlin.collections.Collection<@[FlexibleNullability] kotlin.CharSequence?>? origin=null
+          c: GET_VAR 'c: @[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? declared in <root>.C.jg2' type=@[FlexibleNullability] kotlin.collections.MutableCollection<@[FlexibleNullability] kotlin.CharSequence?>? origin=null
     FIELD DELEGATE name:<$$delegate_0> type:<root>.J visibility:local [final]
       EXPRESSION_BODY
         GET_VAR 'j: <root>.J declared in <root>.C.<init>' type=<root>.J origin=null
diff --git a/compiler/testData/ir/irText/types/javaWildcardType.fir.kt.txt b/compiler/testData/ir/irText/types/javaWildcardType.fir.kt.txt
index 7c474ca4a3f..2dddcccbd5d 100644
--- a/compiler/testData/ir/irText/types/javaWildcardType.fir.kt.txt
+++ b/compiler/testData/ir/irText/types/javaWildcardType.fir.kt.txt
@@ -13,19 +13,19 @@ class C : J, K {
 
   }
 
-  override fun jf1(): @FlexibleNullability Collection<out @FlexibleNullability CharSequence?>? {
+  override fun jf1(): @FlexibleNullability MutableCollection<out @FlexibleNullability CharSequence?>? {
     return <this>.#<$$delegate_0>.jf1()
   }
 
-  override fun jf2(): @FlexibleNullability Collection<@FlexibleNullability CharSequence?>? {
+  override fun jf2(): @FlexibleNullability MutableCollection<@FlexibleNullability CharSequence?>? {
     return <this>.#<$$delegate_0>.jf2()
   }
 
-  override fun jg1(c: @FlexibleNullability Collection<out @FlexibleNullability CharSequence?>?) {
+  override fun jg1(c: @FlexibleNullability MutableCollection<out @FlexibleNullability CharSequence?>?) {
     <this>.#<$$delegate_0>.jg1(c = c)
   }
 
-  override fun jg2(c: @FlexibleNullability Collection<@FlexibleNullability CharSequence?>?) {
+  override fun jg2(c: @FlexibleNullability MutableCollection<@FlexibleNullability CharSequence?>?) {
     <this>.#<$$delegate_0>.jg2(c = c)
   }
 
@@ -49,3 +49,4 @@ class C : J, K {
   local /* final field */ val <$$delegate_1>: K = k
 
 }
+
diff --git a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.ir.txt b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.ir.txt
index b675fa5be5c..1a2a0d5c4ef 100644
--- a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.ir.txt
+++ b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.ir.txt
@@ -182,8 +182,8 @@ FILE fqName:<root> fileName:/enhancedNullabilityInDestructuringAssignment.kt
           <T>: kotlin.collections.IndexedValue<@[EnhancedNullability] <root>.P>
           $receiver: CALL 'public final fun withIndex <T> (): kotlin.collections.Iterable<kotlin.collections.IndexedValue<T of kotlin.collections.CollectionsKt.withIndex>> declared in kotlin.collections.CollectionsKt' type=kotlin.collections.Iterable<kotlin.collections.IndexedValue<@[EnhancedNullability] <root>.P>> origin=null
             <T>: @[EnhancedNullability] <root>.P
-            $receiver: TYPE_OP type=kotlin.collections.List<@[EnhancedNullability] <root>.P> origin=IMPLICIT_NOTNULL typeOperand=kotlin.collections.List<@[EnhancedNullability] <root>.P>
-              CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? origin=null
+            $receiver: TYPE_OP type=kotlin.collections.MutableList<@[EnhancedNullability] <root>.P> origin=IMPLICIT_NOTNULL typeOperand=kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>
+              CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? origin=null
       VAR name:x type:kotlin.Int [val]
         CALL 'public final fun component1 (): kotlin.Int [operator] declared in kotlin.collections.IndexedValue' type=kotlin.Int origin=COMPONENT_N(index=1)
           $this: GET_VAR 'val tmp_3: kotlin.collections.IndexedValue<@[EnhancedNullability] <root>.P> [val] declared in <root>.test4' type=kotlin.collections.IndexedValue<@[EnhancedNullability] <root>.P> origin=null
diff --git a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.kt.txt b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.kt.txt
index 777558a05de..afe3d49db6f 100644
--- a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.kt.txt
+++ b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInDestructuringAssignment.fir.kt.txt
@@ -80,7 +80,7 @@ fun test3() {
 }
 
 fun test4() {
-  val <destruct>: IndexedValue<@EnhancedNullability P> = listOfNotNull() /*!! List<@EnhancedNullability P> */.withIndex<@EnhancedNullability P>().first<IndexedValue<@EnhancedNullability P>>()
+  val <destruct>: IndexedValue<@EnhancedNullability P> = listOfNotNull() /*!! MutableList<@EnhancedNullability P> */.withIndex<@EnhancedNullability P>().first<IndexedValue<@EnhancedNullability P>>()
   val x: Int = <destruct>.component1()
   val y: @EnhancedNullability P = <destruct>.component2() /*!! P */
   use(x = x, y = y)
diff --git a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.ir.txt b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.ir.txt
index e2865e16564..656b41b9abb 100644
--- a/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.ir.txt
+++ b/compiler/testData/ir/irText/types/nullChecks/enhancedNullabilityInForLoop.fir.ir.txt
@@ -7,7 +7,7 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
       BLOCK type=kotlin.Unit origin=FOR_LOOP
         VAR FOR_LOOP_ITERATOR name:tmp_0 type:kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val]
           CALL 'public abstract fun iterator (): kotlin.collections.MutableIterator<E of kotlin.collections.MutableList> [fake_override,operator] declared in kotlin.collections.MutableList' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=FOR_LOOP_ITERATOR
-            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? origin=null
+            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? origin=null
         WHILE label=null origin=FOR_LOOP_INNER_WHILE
           condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [fake_override,operator] declared in kotlin.collections.MutableIterator' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
             $this: GET_VAR 'val tmp_0: kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInListUnused' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=null
@@ -22,7 +22,7 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
       BLOCK type=kotlin.Unit origin=FOR_LOOP
         VAR FOR_LOOP_ITERATOR name:tmp_1 type:kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val]
           CALL 'public abstract fun iterator (): kotlin.collections.MutableIterator<E of kotlin.collections.MutableList> [fake_override,operator] declared in kotlin.collections.MutableList' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=FOR_LOOP_ITERATOR
-            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? origin=null
+            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? origin=null
         WHILE label=null origin=FOR_LOOP_INNER_WHILE
           condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [fake_override,operator] declared in kotlin.collections.MutableIterator' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
             $this: GET_VAR 'val tmp_1: kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInListDestructured' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=null
@@ -42,7 +42,7 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
     BLOCK_BODY
       VAR name:iterator type:kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val]
         CALL 'public abstract fun iterator (): kotlin.collections.MutableIterator<E of kotlin.collections.MutableList> [fake_override,operator] declared in kotlin.collections.MutableList' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=null
-          $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? origin=null
+          $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? origin=null
       WHILE label=null origin=WHILE_LOOP
         condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [fake_override,operator] declared in kotlin.collections.MutableIterator' type=kotlin.Boolean origin=null
           $this: GET_VAR 'val iterator: kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testDesugaredForInList' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=null
@@ -73,7 +73,7 @@ FILE fqName:<root> fileName:/enhancedNullabilityInForLoop.kt
       BLOCK type=kotlin.Unit origin=FOR_LOOP
         VAR FOR_LOOP_ITERATOR name:tmp_4 type:kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val]
           CALL 'public abstract fun iterator (): kotlin.collections.MutableIterator<E of kotlin.collections.MutableList> [fake_override,operator] declared in kotlin.collections.MutableList' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=FOR_LOOP_ITERATOR
-            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.List<@[EnhancedNullability] <root>.P>? origin=null
+            $this: CALL 'public open fun listOfNotNull (): @[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? declared in <root>.J' type=@[FlexibleNullability] kotlin.collections.MutableList<@[EnhancedNullability] <root>.P>? origin=null
         WHILE label=null origin=FOR_LOOP_INNER_WHILE
           condition: CALL 'public abstract fun hasNext (): kotlin.Boolean [fake_override,operator] declared in kotlin.collections.MutableIterator' type=kotlin.Boolean origin=FOR_LOOP_HAS_NEXT
             $this: GET_VAR 'val tmp_4: kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> [val] declared in <root>.testForInListUse' type=kotlin.collections.MutableIterator<@[EnhancedNullability] <root>.P> origin=null