diff --git a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
index c40ff51d6fb..be38e5c294b 100644
--- a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
+++ b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
@@ -168,7 +168,8 @@ class Fir2IrDeclarationStorage(
                         isData = regularClass?.isData == true,
                         isExternal = regularClass?.isExternal == true,
                         isInline = regularClass?.isInline == true,
-                        isExpect = regularClass?.isExpect == true
+                        isExpect = regularClass?.isExpect == true,
+                        isFun = false // TODO FirRegularClass.isFun
                     ).apply {
                         descriptor.bind(this)
                         if (setParent && regularClass != null) {
@@ -216,7 +217,7 @@ class Fir2IrDeclarationStorage(
                     Name.special("<no name provided>"), anonymousObject.classKind,
                     Visibilities.LOCAL, modality,
                     isCompanion = false, isInner = false, isData = false,
-                    isExternal = false, isInline = false, isExpect = false
+                    isExternal = false, isInline = false, isExpect = false, isFun = false
                 ).apply {
                     descriptor.bind(this)
                     declareThisReceiver()
@@ -236,7 +237,7 @@ class Fir2IrDeclarationStorage(
                     enumEntry.name, anonymousObject.classKind,
                     Visibilities.LOCAL, modality,
                     isCompanion = false, isInner = false, isData = false,
-                    isExternal = false, isInline = false, isExpect = false
+                    isExternal = false, isInline = false, isExpect = false, isFun = false
                 ).apply {
                     descriptor.bind(this)
                     declareThisReceiver()
diff --git a/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/fir/Fir2IrTextTestGenerated.java b/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/fir/Fir2IrTextTestGenerated.java
index 84daeaeca1e..280503b34d7 100644
--- a/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/fir/Fir2IrTextTestGenerated.java
+++ b/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/fir/Fir2IrTextTestGenerated.java
@@ -1420,6 +1420,39 @@ public class Fir2IrTextTestGenerated extends AbstractFir2IrTextTest {
             }
         }
 
+        @TestMetadata("compiler/testData/ir/irText/expressions/funInterface")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class FunInterface extends AbstractFir2IrTextTest {
+            private void runTest(String testDataFilePath) throws Exception {
+                KotlinTestUtils.runTestWithCustomIgnoreDirective(this::doTest, TargetBackend.ANY, testDataFilePath, "// IGNORE_BACKEND_FIR: ");
+            }
+
+            public void testAllFilesPresentInFunInterface() throws Exception {
+                KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/ir/irText/expressions/funInterface"), Pattern.compile("^(.+)\\.kt$"), null, true);
+            }
+
+            @TestMetadata("basicFunInterfaceConversion.kt")
+            public void testBasicFunInterfaceConversion() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.kt");
+            }
+
+            @TestMetadata("castFromAny.kt")
+            public void testCastFromAny() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt");
+            }
+
+            @TestMetadata("partialSam.kt")
+            public void testPartialSam() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/partialSam.kt");
+            }
+
+            @TestMetadata("samConversionsWithSmartCasts.kt")
+            public void testSamConversionsWithSmartCasts() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt");
+            }
+        }
+
         @TestMetadata("compiler/testData/ir/irText/expressions/sam")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/AbstractSuspendFunctionsLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/AbstractSuspendFunctionsLowering.kt
index a9339f691bd..5521bcb25f0 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/AbstractSuspendFunctionsLowering.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/AbstractSuspendFunctionsLowering.kt
@@ -294,7 +294,8 @@ abstract class AbstractSuspendFunctionsLowering<C : CommonBackendContext>(val co
                 isData = false,
                 isExternal = false,
                 isInline = false,
-                isExpect = false
+                isExpect = false,
+                isFun = false
             ).apply {
                 d.bind(this)
                 parent = irFunction.parent
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt
index 3448e6420f3..8e7545f8340 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/builders/declarations/declarationBuilders.kt
@@ -5,10 +5,9 @@
 
 package org.jetbrains.kotlin.ir.builders.declarations
 
-import org.jetbrains.kotlin.backend.common.descriptors.*
+import org.jetbrains.kotlin.backend.common.descriptors.synthesizedName
 import org.jetbrains.kotlin.backend.common.ir.copyTo
 import org.jetbrains.kotlin.descriptors.*
-import org.jetbrains.kotlin.descriptors.annotations.Annotations
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.impl.*
 import org.jetbrains.kotlin.ir.descriptors.*
@@ -27,7 +26,7 @@ fun IrClassBuilder.buildClass(): IrClass {
         IrClassSymbolImpl(wrappedDescriptor),
         name, kind, visibility, modality,
         isCompanion = isCompanion, isInner = isInner, isData = isData, isExternal = isExternal,
-        isInline = isInline, isExpect = isExpect
+        isInline = isInline, isExpect = isExpect, isFun = isFun
     ).also {
         wrappedDescriptor.bind(it)
     }
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsSharedVariablesManager.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsSharedVariablesManager.kt
index 2d3649ec63e..e051a448181 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsSharedVariablesManager.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsSharedVariablesManager.kt
@@ -127,7 +127,7 @@ class JsSharedVariablesManager(val builtIns: IrBuiltIns, val implicitDeclaration
             UNDEFINED_OFFSET, UNDEFINED_OFFSET, JsLoweredDeclarationOrigin.JS_CLOSURE_BOX_CLASS_DECLARATION, IrClassSymbolImpl(descriptor),
             Name.identifier(boxTypeName), ClassKind.CLASS, Visibilities.PUBLIC, Modality.FINAL,
             isCompanion = false, isInner = false, isData = false, isExternal = false,
-            isInline = false, isExpect = false
+            isInline = false, isExpect = false, isFun = false
         )
 
         descriptor.bind(declaration)
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmGeneratorExtensions.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmGeneratorExtensions.kt
index b8e68308261..4f3121f515e 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmGeneratorExtensions.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmGeneratorExtensions.kt
@@ -58,8 +58,8 @@ class JvmGeneratorExtensions(private val generateFacades: Boolean = true) : Gene
         }
 
         override fun getSubstitutedFunctionTypeForSamType(samType: KotlinType): KotlinType {
-            val descriptor = samType.constructor.declarationDescriptor as? JavaClassDescriptor
-                ?: throw AssertionError("SAM should be represented by a Java class: $samType")
+            val descriptor = samType.constructor.declarationDescriptor as? ClassDescriptor
+                ?: throw AssertionError("SAM should be represented by a class: $samType")
             val singleAbstractMethod = getSingleAbstractMethodOrNull(descriptor)
                 ?: throw AssertionError("$descriptor should have a single abstract method")
             val unsubstitutedFunctionType = getFunctionTypeForAbstractMethod(singleAbstractMethod, false)
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/JvmDeclarationFactory.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/JvmDeclarationFactory.kt
index 6e5b5c29406..484dbdce7e0 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/JvmDeclarationFactory.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/descriptors/JvmDeclarationFactory.kt
@@ -236,7 +236,8 @@ class JvmDeclarationFactory(
                 isData = false,
                 isExternal = false,
                 isInline = false,
-                isExpect = false
+                isExpect = false,
+                isFun = false
             ).apply {
                 descriptor.bind(this)
                 parent = interfaceClass
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/FileClassLowering.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/FileClassLowering.kt
index d725431e104..5654a32a28c 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/FileClassLowering.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/FileClassLowering.kt
@@ -88,7 +88,8 @@ private class FileClassLowering(val context: JvmBackendContext) : FileLoweringPa
             isData = false,
             isExternal = false,
             isInline = false,
-            isExpect = false
+            isExpect = false,
+            isFun = false
         ).apply {
             descriptor.bind(this)
             superTypes.add(context.irBuiltIns.anyType)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/declarations/IrClassBuilder.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/declarations/IrClassBuilder.kt
index 67a9e37ad54..c5b1f03788a 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/declarations/IrClassBuilder.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/builders/declarations/IrClassBuilder.kt
@@ -32,5 +32,6 @@ class IrClassBuilder : IrDeclarationBuilder() {
         isExternal = from.isExternal
         isInline = from.isInline
         isExpect = from.isExpect
+        isFun = from.isFun
     }
 }
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrClass.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrClass.kt
index d0d9eacdcea..65a20c8fd3e 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrClass.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/IrClass.kt
@@ -39,6 +39,7 @@ interface IrClass :
     val isExternal: Boolean
     val isInline: Boolean
     val isExpect: Boolean
+    val isFun: Boolean
 
     val superTypes: MutableList<IrType>
 
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
index e17bfd8ea8d..cd6eb0de4bd 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
@@ -44,7 +44,8 @@ class IrClassImpl(
     override val isData: Boolean,
     override val isExternal: Boolean,
     override val isInline: Boolean,
-    override val isExpect: Boolean
+    override val isExpect: Boolean,
+    override val isFun: Boolean
 ) :
     IrDeclarationBase(startOffset, endOffset, origin),
     IrClass {
@@ -66,7 +67,8 @@ class IrClassImpl(
                 isData = symbol.descriptor.isData,
                 isExternal = symbol.descriptor.isEffectivelyExternal(),
                 isInline = symbol.descriptor.isInline,
-                isExpect = symbol.descriptor.isExpect
+                isExpect = symbol.descriptor.isExpect,
+                isFun = symbol.descriptor.isFun
             )
 
     init {
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
index c4dac814a3d..1222fc0d2b3 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
@@ -35,6 +35,7 @@ class IrLazyClass(
     override val isExternal: Boolean,
     override val isInline: Boolean,
     override val isExpect: Boolean,
+    override val isFun: Boolean,
     stubGenerator: DeclarationStubGenerator,
     typeTranslator: TypeTranslator
 ) :
@@ -59,6 +60,7 @@ class IrLazyClass(
                 isExternal = symbol.descriptor.isEffectivelyExternal(),
                 isInline = symbol.descriptor.isInline,
                 isExpect = symbol.descriptor.isExpect,
+                isFun = symbol.descriptor.isFun,
                 stubGenerator = stubGenerator,
                 typeTranslator = TypeTranslator
             )
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyIrTreeWithSymbols.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyIrTreeWithSymbols.kt
index 1430cdbe878..4a7b6c44122 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyIrTreeWithSymbols.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeepCopyIrTreeWithSymbols.kt
@@ -142,12 +142,13 @@ open class DeepCopyIrTreeWithSymbols(
             declaration.kind,
             declaration.visibility,
             declaration.modality,
-            declaration.isCompanion,
-            declaration.isInner,
-            declaration.isData,
-            declaration.isExternal,
-            declaration.isInline,
-            declaration.isExpect
+            isCompanion = declaration.isCompanion,
+            isInner = declaration.isInner,
+            isData = declaration.isData,
+            isExternal = declaration.isExternal,
+            isInline = declaration.isInline,
+            isExpect = declaration.isExpect,
+            isFun = declaration.isFun
         ).apply {
             transformAnnotations(declaration)
             copyTypeParametersFrom(declaration)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt
index 94a28b9e0ae..92cc9186eff 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/RenderIrElement.kt
@@ -462,7 +462,8 @@ class RenderIrElementVisitor(private val normalizeNames: Boolean = false) : IrEl
             "data".takeIf { isData },
             "external".takeIf { isExternal },
             "inline".takeIf { isInline },
-            "expect".takeIf { isExpect }
+            "expect".takeIf { isExpect },
+            "fun".takeIf { isFun }
         )
 
     override fun visitVariable(declaration: IrVariable, data: Nothing?): String =
diff --git a/compiler/ir/serialization.common/src/KotlinIr.proto b/compiler/ir/serialization.common/src/KotlinIr.proto
index 8d8aa973990..6afeab3fbaa 100644
--- a/compiler/ir/serialization.common/src/KotlinIr.proto
+++ b/compiler/ir/serialization.common/src/KotlinIr.proto
@@ -648,6 +648,7 @@ message IrClass {
   required IrDeclarationContainer declaration_container = 13;
   repeated int32 super_type = 14;
   required bool is_expect = 15;
+  required bool is_fun = 16;
 }
 
 message IrTypeAlias {
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
index 3810546e4a7..5ed26eb9863 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileDeserializer.kt
@@ -980,7 +980,8 @@ abstract class IrFileDeserializer(
                     isData = proto.isData,
                     isExternal = proto.isExternal,
                     isInline = proto.isInline,
-                    isExpect = proto.isExpect
+                    isExpect = proto.isExpect,
+                    isFun = proto.isFun
                 )
             }.usingParent {
                 proto.declarationContainer.declarationList.mapTo(declarations) { deserializeDeclaration(it) }
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
index a2c249bfb50..3d123c0c20e 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrFileSerializer.kt
@@ -1198,6 +1198,7 @@ open class IrFileSerializer(
             .setIsExternal(clazz.isExternal)
             .setIsInline(clazz.isInline)
             .setIsExpect(clazz.isExpect)
+            .setIsFun(clazz.isFun)
             .setTypeParameters(serializeIrTypeParameterContainer(clazz.typeParameters))
             .setDeclarationContainer(serializeIrDeclarationContainer(clazz.declarations))
         clazz.superTypes.forEach {
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClass.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClass.java
index 77be52d4303..9c614d2a7a0 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClass.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClass.java
@@ -198,6 +198,11 @@ public final class IrClass extends
             isExpect_ = input.readBool();
             break;
           }
+          case 128: {
+            bitField0_ |= 0x00004000;
+            isFun_ = input.readBool();
+            break;
+          }
         }
       }
     } catch (org.jetbrains.kotlin.protobuf.InvalidProtocolBufferException e) {
@@ -475,6 +480,21 @@ public final class IrClass extends
     return isExpect_;
   }
 
+  public static final int IS_FUN_FIELD_NUMBER = 16;
+  private boolean isFun_;
+  /**
+   * <code>required bool is_fun = 16;</code>
+   */
+  public boolean hasIsFun() {
+    return ((bitField0_ & 0x00004000) == 0x00004000);
+  }
+  /**
+   * <code>required bool is_fun = 16;</code>
+   */
+  public boolean getIsFun() {
+    return isFun_;
+  }
+
   private void initFields() {
     base_ = org.jetbrains.kotlin.backend.common.serialization.proto.IrDeclarationBase.getDefaultInstance();
     name_ = 0;
@@ -491,6 +511,7 @@ public final class IrClass extends
     declarationContainer_ = org.jetbrains.kotlin.backend.common.serialization.proto.IrDeclarationContainer.getDefaultInstance();
     superType_ = java.util.Collections.emptyList();
     isExpect_ = false;
+    isFun_ = false;
   }
   private byte memoizedIsInitialized = -1;
   public final boolean isInitialized() {
@@ -550,6 +571,10 @@ public final class IrClass extends
       memoizedIsInitialized = 0;
       return false;
     }
+    if (!hasIsFun()) {
+      memoizedIsInitialized = 0;
+      return false;
+    }
     if (!getBase().isInitialized()) {
       memoizedIsInitialized = 0;
       return false;
@@ -624,6 +649,9 @@ public final class IrClass extends
     if (((bitField0_ & 0x00002000) == 0x00002000)) {
       output.writeBool(15, isExpect_);
     }
+    if (((bitField0_ & 0x00004000) == 0x00004000)) {
+      output.writeBool(16, isFun_);
+    }
     output.writeRawBytes(unknownFields);
   }
 
@@ -698,6 +726,10 @@ public final class IrClass extends
       size += org.jetbrains.kotlin.protobuf.CodedOutputStream
         .computeBoolSize(15, isExpect_);
     }
+    if (((bitField0_ & 0x00004000) == 0x00004000)) {
+      size += org.jetbrains.kotlin.protobuf.CodedOutputStream
+        .computeBoolSize(16, isFun_);
+    }
     size += unknownFields.size();
     memoizedSerializedSize = size;
     return size;
@@ -822,6 +854,8 @@ public final class IrClass extends
       bitField0_ = (bitField0_ & ~0x00002000);
       isExpect_ = false;
       bitField0_ = (bitField0_ & ~0x00004000);
+      isFun_ = false;
+      bitField0_ = (bitField0_ & ~0x00008000);
       return this;
     }
 
@@ -906,6 +940,10 @@ public final class IrClass extends
         to_bitField0_ |= 0x00002000;
       }
       result.isExpect_ = isExpect_;
+      if (((from_bitField0_ & 0x00008000) == 0x00008000)) {
+        to_bitField0_ |= 0x00004000;
+      }
+      result.isFun_ = isFun_;
       result.bitField0_ = to_bitField0_;
       return result;
     }
@@ -964,6 +1002,9 @@ public final class IrClass extends
       if (other.hasIsExpect()) {
         setIsExpect(other.getIsExpect());
       }
+      if (other.hasIsFun()) {
+        setIsFun(other.getIsFun());
+      }
       setUnknownFields(
           getUnknownFields().concat(other.unknownFields));
       return this;
@@ -1022,6 +1063,10 @@ public final class IrClass extends
         
         return false;
       }
+      if (!hasIsFun()) {
+        
+        return false;
+      }
       if (!getBase().isInitialized()) {
         
         return false;
@@ -1742,6 +1787,38 @@ public final class IrClass extends
       return this;
     }
 
+    private boolean isFun_ ;
+    /**
+     * <code>required bool is_fun = 16;</code>
+     */
+    public boolean hasIsFun() {
+      return ((bitField0_ & 0x00008000) == 0x00008000);
+    }
+    /**
+     * <code>required bool is_fun = 16;</code>
+     */
+    public boolean getIsFun() {
+      return isFun_;
+    }
+    /**
+     * <code>required bool is_fun = 16;</code>
+     */
+    public Builder setIsFun(boolean value) {
+      bitField0_ |= 0x00008000;
+      isFun_ = value;
+      
+      return this;
+    }
+    /**
+     * <code>required bool is_fun = 16;</code>
+     */
+    public Builder clearIsFun() {
+      bitField0_ = (bitField0_ & ~0x00008000);
+      isFun_ = false;
+      
+      return this;
+    }
+
     // @@protoc_insertion_point(builder_scope:org.jetbrains.kotlin.backend.common.serialization.proto.IrClass)
   }
 
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClassOrBuilder.java b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClassOrBuilder.java
index 3b8911e6f27..8eb261aaaa0 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClassOrBuilder.java
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/proto/IrClassOrBuilder.java
@@ -153,4 +153,13 @@ public interface IrClassOrBuilder extends
    * <code>required bool is_expect = 15;</code>
    */
   boolean getIsExpect();
+
+  /**
+   * <code>required bool is_fun = 16;</code>
+   */
+  boolean hasIsFun();
+  /**
+   * <code>required bool is_fun = 16;</code>
+   */
+  boolean getIsFun();
 }
\ No newline at end of file
diff --git a/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt b/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
index 0d2cf38e9bc..d114edbee1c 100644
--- a/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
+++ b/compiler/testData/codegen/box/funInterface/basicFunInterfaceConversion.kt
@@ -1,7 +1,6 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
 // IGNORE_BACKEND_FIR: JVM_IR
-// IGNORE_BACKEND: JVM_IR
 
 fun interface Foo {
     fun invoke(): String
diff --git a/compiler/testData/codegen/box/funInterface/castFromAny.kt b/compiler/testData/codegen/box/funInterface/castFromAny.kt
index f53fca36ca6..51a293c66dc 100644
--- a/compiler/testData/codegen/box/funInterface/castFromAny.kt
+++ b/compiler/testData/codegen/box/funInterface/castFromAny.kt
@@ -1,7 +1,7 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
 // IGNORE_BACKEND_FIR: JVM_IR
-// IGNORE_BACKEND: JVM_IR
+
 
 fun interface KRunnable {
     fun invoke()
diff --git a/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt b/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
index f0ef007992f..812c9c45e48 100644
--- a/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
+++ b/compiler/testData/codegen/box/funInterface/inlinedSamWrapper.kt
@@ -1,7 +1,6 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
 // IGNORE_BACKEND_FIR: JVM_IR
-// IGNORE_BACKEND: JVM_IR
 // WITH_RUNTIME
 
 fun interface MyRunnable {
diff --git a/compiler/testData/codegen/box/funInterface/nullableSam.kt b/compiler/testData/codegen/box/funInterface/nullableSam.kt
index 328994b7298..fe4b6581032 100644
--- a/compiler/testData/codegen/box/funInterface/nullableSam.kt
+++ b/compiler/testData/codegen/box/funInterface/nullableSam.kt
@@ -1,6 +1,5 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND: JVM_IR
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 
diff --git a/compiler/testData/codegen/box/funInterface/partialSam.kt b/compiler/testData/codegen/box/funInterface/partialSam.kt
index f7e411f2f26..058d058bf5d 100644
--- a/compiler/testData/codegen/box/funInterface/partialSam.kt
+++ b/compiler/testData/codegen/box/funInterface/partialSam.kt
@@ -1,6 +1,5 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND: JVM_IR
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 
diff --git a/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt b/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
index 33301006563..7353f2755e9 100644
--- a/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
+++ b/compiler/testData/codegen/box/funInterface/receiverEvaluatedOnce.kt
@@ -1,6 +1,5 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND: JVM_IR
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 
diff --git a/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt b/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
index 7674a2ef4f9..b75e31cbd95 100644
--- a/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
+++ b/compiler/testData/codegen/box/funInterface/suspendFunInterfaceConversionCodegen.kt
@@ -1,6 +1,5 @@
 // !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND: JVM_IR
 // IGNORE_BACKEND_FIR: JVM_IR
 // WITH_COROUTINES
 // WITH_RUNTIME
diff --git a/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.fir.txt b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.fir.txt
new file mode 100644
index 00000000000..c31b6c40da7
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.fir.txt
@@ -0,0 +1,32 @@
+FILE fqName:<root> fileName:/basicFunInterfaceConversion.kt
+  CLASS INTERFACE name:Foo modality:ABSTRACT visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.Foo
+    FUN name:invoke visibility:public modality:ABSTRACT <> ($this:<root>.Foo) returnType:kotlin.String
+      $this: VALUE_PARAMETER name:<this> type:<root>.Foo
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:foo visibility:public modality:FINAL <> (f:<root>.Foo) returnType:kotlin.String
+    VALUE_PARAMETER name:f index:0 type:<root>.Foo
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun foo (f: <root>.Foo): kotlin.String declared in <root>'
+        CALL 'public abstract fun invoke (): kotlin.String declared in <root>.Foo' type=kotlin.String origin=null
+          $this: GET_VAR 'f: <root>.Foo declared in <root>.foo' type=<root>.Foo origin=null
+  FUN name:test visibility:public modality:FINAL <> () returnType:kotlin.String
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun test (): kotlin.String declared in <root>'
+        CALL 'public final fun foo (f: <root>.Foo): kotlin.String declared in <root>' type=kotlin.String origin=null
+          f: FUN_EXPR type=kotlin.Function0<kotlin.String> origin=LAMBDA
+            FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> () returnType:kotlin.String
+              BLOCK_BODY
+                CONST String type=kotlin.String value="OK"
diff --git a/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.kt b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.kt
new file mode 100644
index 00000000000..94f6bbcebbd
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.kt
@@ -0,0 +1,9 @@
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+
+fun interface Foo {
+    fun invoke(): String
+}
+
+fun foo(f: Foo) = f.invoke()
+
+fun test() = foo { "OK" }
\ No newline at end of file
diff --git a/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.txt b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.txt
new file mode 100644
index 00000000000..c50d837d025
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.txt
@@ -0,0 +1,34 @@
+FILE fqName:<root> fileName:/basicFunInterfaceConversion.kt
+  CLASS INTERFACE name:Foo modality:ABSTRACT visibility:public [fun] superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.Foo
+    FUN name:invoke visibility:public modality:ABSTRACT <> ($this:<root>.Foo) returnType:kotlin.String
+      $this: VALUE_PARAMETER name:<this> type:<root>.Foo
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:foo visibility:public modality:FINAL <> (f:<root>.Foo) returnType:kotlin.String
+    VALUE_PARAMETER name:f index:0 type:<root>.Foo
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun foo (f: <root>.Foo): kotlin.String declared in <root>'
+        CALL 'public abstract fun invoke (): kotlin.String declared in <root>.Foo' type=kotlin.String origin=null
+          $this: GET_VAR 'f: <root>.Foo declared in <root>.foo' type=<root>.Foo origin=null
+  FUN name:test visibility:public modality:FINAL <> () returnType:kotlin.String
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun test (): kotlin.String declared in <root>'
+        CALL 'public final fun foo (f: <root>.Foo): kotlin.String declared in <root>' type=kotlin.String origin=null
+          f: TYPE_OP type=<root>.Foo origin=SAM_CONVERSION typeOperand=<root>.Foo
+            FUN_EXPR type=kotlin.Function0<kotlin.String> origin=LAMBDA
+              FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> () returnType:kotlin.String
+                BLOCK_BODY
+                  RETURN type=kotlin.Nothing from='local final fun <anonymous> (): kotlin.String declared in <root>.test'
+                    CONST String type=kotlin.String value="OK"
diff --git a/compiler/testData/ir/irText/expressions/funInterface/castFromAny.fir.txt b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.fir.txt
new file mode 100644
index 00000000000..cc65bb04717
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.fir.txt
@@ -0,0 +1,26 @@
+FILE fqName:<root> fileName:/castFromAny.kt
+  CLASS INTERFACE name:KRunnable modality:ABSTRACT visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.KRunnable
+    FUN name:invoke visibility:public modality:ABSTRACT <> ($this:<root>.KRunnable) returnType:kotlin.Unit
+      $this: VALUE_PARAMETER name:<this> type:<root>.KRunnable
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:test visibility:public modality:FINAL <> (a:kotlin.Any?) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any?
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+        GET_VAR 'a: kotlin.Any? declared in <root>.test' type=kotlin.Any? origin=null
+      CALL 'public abstract fun invoke (): kotlin.Unit declared in <root>.KRunnable' type=kotlin.Unit origin=null
+        $this: CALL 'public final fun KRunnable (block: kotlin.Function0<kotlin.Unit>): <root>.KRunnable declared in <root>' type=<root>.KRunnable origin=null
+          block: GET_VAR 'a: kotlin.Any? declared in <root>.test' type=kotlin.Function0<kotlin.Unit> origin=null
diff --git a/compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt
new file mode 100644
index 00000000000..9581e8ee90f
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt
@@ -0,0 +1,11 @@
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+
+fun interface KRunnable {
+    fun invoke()
+}
+
+fun test(a: Any?) {
+    a as () -> Unit
+    KRunnable(a).invoke()
+}
+
diff --git a/compiler/testData/ir/irText/expressions/funInterface/castFromAny.txt b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.txt
new file mode 100644
index 00000000000..1c13506c9b6
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/castFromAny.txt
@@ -0,0 +1,28 @@
+FILE fqName:<root> fileName:/castFromAny.kt
+  CLASS INTERFACE name:KRunnable modality:ABSTRACT visibility:public [fun] superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.KRunnable
+    FUN name:invoke visibility:public modality:ABSTRACT <> ($this:<root>.KRunnable) returnType:kotlin.Unit
+      $this: VALUE_PARAMETER name:<this> type:<root>.KRunnable
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:test visibility:public modality:FINAL <> (a:kotlin.Any?) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any?
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+          GET_VAR 'a: kotlin.Any? declared in <root>.test' type=kotlin.Any? origin=null
+      CALL 'public abstract fun invoke (): kotlin.Unit declared in <root>.KRunnable' type=kotlin.Unit origin=null
+        $this: TYPE_OP type=<root>.KRunnable origin=SAM_CONVERSION typeOperand=<root>.KRunnable
+          TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=IMPLICIT_CAST typeOperand=kotlin.Function0<kotlin.Unit>
+            GET_VAR 'a: kotlin.Any? declared in <root>.test' type=kotlin.Any? origin=null
diff --git a/compiler/testData/ir/irText/expressions/funInterface/partialSam.fir.txt b/compiler/testData/ir/irText/expressions/funInterface/partialSam.fir.txt
new file mode 100644
index 00000000000..722e3808df3
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/partialSam.fir.txt
@@ -0,0 +1,128 @@
+FILE fqName:<root> fileName:/partialSam.kt
+  CLASS INTERFACE name:Fn modality:ABSTRACT visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.Fn
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?]
+    TYPE_PARAMETER name:R index:1 variance: superTypes:[kotlin.Any?]
+    FUN name:run visibility:public modality:ABSTRACT <> ($this:<root>.Fn, s:kotlin.String, i:kotlin.Int, t:T of <root>.Fn) returnType:R of <root>.Fn
+      $this: VALUE_PARAMETER name:<this> type:<root>.Fn
+      VALUE_PARAMETER name:s index:0 type:kotlin.String
+      VALUE_PARAMETER name:i index:1 type:kotlin.Int
+      VALUE_PARAMETER name:t index:2 type:T of <root>.Fn
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  CLASS CLASS name:J modality:FINAL visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.J
+    CONSTRUCTOR visibility:public <> () returnType:<root>.J [primary]
+      BLOCK_BODY
+        DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+        INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:J modality:FINAL visibility:public superTypes:[kotlin.Any]'
+    FUN name:runConversion visibility:public modality:FINAL <> ($this:<root>.J, f1:<root>.Fn<kotlin.String, kotlin.Int>, f2:<root>.Fn<kotlin.Int, kotlin.String>) returnType:kotlin.Int
+      $this: VALUE_PARAMETER name:<this> type:<root>.J
+      VALUE_PARAMETER name:f1 index:0 type:<root>.Fn<kotlin.String, kotlin.Int>
+      VALUE_PARAMETER name:f2 index:1 type:<root>.Fn<kotlin.Int, kotlin.String>
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J'
+          CALL 'public abstract fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.String): kotlin.Int declared in <root>.Fn' type=kotlin.Int origin=null
+            $this: GET_VAR 'f1: <root>.Fn<kotlin.String, kotlin.Int> declared in <root>.J.runConversion' type=<root>.Fn<kotlin.String, kotlin.Int> origin=null
+            s: CONST String type=kotlin.String value="Bar"
+            i: CONST Int type=kotlin.Int value=1
+            t: CALL 'public abstract fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.Int): kotlin.String declared in <root>.Fn' type=kotlin.String origin=null
+              $this: GET_VAR 'f2: <root>.Fn<kotlin.Int, kotlin.String> declared in <root>.J.runConversion' type=<root>.Fn<kotlin.Int, kotlin.String> origin=null
+              s: CONST String type=kotlin.String value="Foo"
+              i: CONST Int type=kotlin.Int value=42
+              t: CONST Int type=kotlin.Int value=239
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  PROPERTY name:fsi visibility:public modality:FINAL [val]
+    FIELD PROPERTY_BACKING_FIELD name:fsi type:<uninitialized parent>.<anonymous> visibility:private [final,static]
+      EXPRESSION_BODY
+        BLOCK type=<root>.fsi.<no name provided> origin=OBJECT_LITERAL
+          CLASS OBJECT name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.String, kotlin.Int>]
+            $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.fsi.<no name provided>
+            CONSTRUCTOR visibility:private <> () returnType:kotlin.Any [primary]
+              BLOCK_BODY
+                DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+                INSTANCE_INITIALIZER_CALL classDescriptor='CLASS OBJECT name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.String, kotlin.Int>]'
+            FUN name:run visibility:public modality:FINAL <> ($this:<root>.fsi.<no name provided>, s:kotlin.String, i:kotlin.Int, t:kotlin.String) returnType:kotlin.Int
+              $this: VALUE_PARAMETER name:<this> type:<root>.fsi.<no name provided>
+              VALUE_PARAMETER name:s index:0 type:kotlin.String
+              VALUE_PARAMETER name:i index:1 type:kotlin.Int
+              VALUE_PARAMETER name:t index:2 type:kotlin.String
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='public final fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.String): kotlin.Int declared in <root>.fsi.<no name provided>'
+                  CONST Int type=kotlin.Int value=1
+          CONSTRUCTOR_CALL 'private constructor <init> () [primary] declared in <root>.fsi.<no name provided>' type=<root>.fsi.<no name provided> origin=null
+    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-fsi> visibility:public modality:FINAL <> () returnType:<uninitialized parent>.<anonymous>
+      correspondingProperty: PROPERTY name:fsi visibility:public modality:FINAL [val]
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun <get-fsi> (): <uninitialized parent>.<anonymous> declared in <root>'
+          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:fsi type:<uninitialized parent>.<anonymous> visibility:private [final,static]' type=<uninitialized parent>.<anonymous> origin=null
+  PROPERTY name:fis visibility:public modality:FINAL [val]
+    FIELD PROPERTY_BACKING_FIELD name:fis type:<uninitialized parent>.<anonymous> visibility:private [final,static]
+      EXPRESSION_BODY
+        BLOCK type=<root>.fis.<no name provided> origin=OBJECT_LITERAL
+          CLASS OBJECT name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.Int, kotlin.String>]
+            $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.fis.<no name provided>
+            CONSTRUCTOR visibility:private <> () returnType:kotlin.Any [primary]
+              BLOCK_BODY
+                DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+                INSTANCE_INITIALIZER_CALL classDescriptor='CLASS OBJECT name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.Int, kotlin.String>]'
+            FUN name:run visibility:public modality:FINAL <> ($this:<root>.fis.<no name provided>, s:kotlin.String, i:kotlin.Int, t:kotlin.Int) returnType:kotlin.String
+              $this: VALUE_PARAMETER name:<this> type:<root>.fis.<no name provided>
+              VALUE_PARAMETER name:s index:0 type:kotlin.String
+              VALUE_PARAMETER name:i index:1 type:kotlin.Int
+              VALUE_PARAMETER name:t index:2 type:kotlin.Int
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='public final fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.Int): kotlin.String declared in <root>.fis.<no name provided>'
+                  CONST String type=kotlin.String value=""
+          CONSTRUCTOR_CALL 'private constructor <init> () [primary] declared in <root>.fis.<no name provided>' type=<root>.fis.<no name provided> origin=null
+    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-fis> visibility:public modality:FINAL <> () returnType:<uninitialized parent>.<anonymous>
+      correspondingProperty: PROPERTY name:fis visibility:public modality:FINAL [val]
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun <get-fis> (): <uninitialized parent>.<anonymous> declared in <root>'
+          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:fis type:<uninitialized parent>.<anonymous> visibility:private [final,static]' type=<uninitialized parent>.<anonymous> origin=null
+  FUN name:test visibility:public modality:FINAL <> (j:<root>.J) returnType:kotlin.Unit
+    VALUE_PARAMETER name:j index:0 type:<root>.J
+    BLOCK_BODY
+      CALL 'public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J' type=kotlin.Int origin=null
+        $this: GET_VAR 'j: <root>.J declared in <root>.test' type=<root>.J origin=null
+        f1: CALL 'public final fun <get-fsi> (): <uninitialized parent>.<anonymous> declared in <root>' type=<uninitialized parent>.<anonymous> origin=null
+        f2: FUN_EXPR type=kotlin.Function3<kotlin.String, kotlin.Int, kotlin.Int, kotlin.String> origin=LAMBDA
+          FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> (s:kotlin.String, i:kotlin.Int, ti:kotlin.Int) returnType:kotlin.String
+            VALUE_PARAMETER name:s index:0 type:kotlin.String
+            VALUE_PARAMETER name:i index:1 type:kotlin.Int
+            VALUE_PARAMETER name:ti index:2 type:kotlin.Int
+            BLOCK_BODY
+              CONST String type=kotlin.String value=""
+      CALL 'public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J' type=kotlin.Int origin=null
+        $this: GET_VAR 'j: <root>.J declared in <root>.test' type=<root>.J origin=null
+        f1: FUN_EXPR type=kotlin.Function3<kotlin.String, kotlin.Int, kotlin.String, kotlin.Int> origin=LAMBDA
+          FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> (s:kotlin.String, i:kotlin.Int, ts:kotlin.String) returnType:kotlin.Int
+            VALUE_PARAMETER name:s index:0 type:kotlin.String
+            VALUE_PARAMETER name:i index:1 type:kotlin.Int
+            VALUE_PARAMETER name:ts index:2 type:kotlin.String
+            BLOCK_BODY
+              CONST Int type=kotlin.Int value=1
+        f2: CALL 'public final fun <get-fis> (): <uninitialized parent>.<anonymous> declared in <root>' type=<uninitialized parent>.<anonymous> origin=null
diff --git a/compiler/testData/ir/irText/expressions/funInterface/partialSam.kt b/compiler/testData/ir/irText/expressions/funInterface/partialSam.kt
new file mode 100644
index 00000000000..9050b87fc45
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/partialSam.kt
@@ -0,0 +1,28 @@
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND: JVM_IR
+// IGNORE_BACKEND_FIR: JVM_IR
+// WITH_RUNTIME
+
+fun interface Fn<T, R> {
+    fun run(s: String, i: Int, t: T): R
+}
+
+class J {
+    fun runConversion(f1: Fn<String, Int>, f2: Fn<Int, String>): Int {
+        return f1.run("Bar", 1, f2.run("Foo", 42, 239))
+    }
+}
+
+val fsi = object : Fn<String, Int> {
+    override fun run(s: String, i: Int, t: String): Int = 1
+}
+
+val fis = object : Fn<Int, String> {
+    override fun run(s: String, i: Int, t: Int): String = ""
+}
+
+fun test(j: J) {
+    j.runConversion(fsi) { s, i, ti -> ""}
+    j.runConversion({ s, i, ts -> 1 }, fis)
+}
\ No newline at end of file
diff --git a/compiler/testData/ir/irText/expressions/funInterface/partialSam.txt b/compiler/testData/ir/irText/expressions/funInterface/partialSam.txt
new file mode 100644
index 00000000000..7772abe4a0a
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/partialSam.txt
@@ -0,0 +1,164 @@
+FILE fqName:<root> fileName:/partialSam.kt
+  CLASS INTERFACE name:Fn modality:ABSTRACT visibility:public [fun] superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.Fn<T of <root>.Fn, R of <root>.Fn>
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?]
+    TYPE_PARAMETER name:R index:1 variance: superTypes:[kotlin.Any?]
+    FUN name:run visibility:public modality:ABSTRACT <> ($this:<root>.Fn<T of <root>.Fn, R of <root>.Fn>, s:kotlin.String, i:kotlin.Int, t:T of <root>.Fn) returnType:R of <root>.Fn
+      $this: VALUE_PARAMETER name:<this> type:<root>.Fn<T of <root>.Fn, R of <root>.Fn>
+      VALUE_PARAMETER name:s index:0 type:kotlin.String
+      VALUE_PARAMETER name:i index:1 type:kotlin.Int
+      VALUE_PARAMETER name:t index:2 type:T of <root>.Fn
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  CLASS CLASS name:J modality:FINAL visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.J
+    CONSTRUCTOR visibility:public <> () returnType:<root>.J [primary]
+      BLOCK_BODY
+        DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+        INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:J modality:FINAL visibility:public superTypes:[kotlin.Any]'
+    FUN name:runConversion visibility:public modality:FINAL <> ($this:<root>.J, f1:<root>.Fn<kotlin.String, kotlin.Int>, f2:<root>.Fn<kotlin.Int, kotlin.String>) returnType:kotlin.Int
+      $this: VALUE_PARAMETER name:<this> type:<root>.J
+      VALUE_PARAMETER name:f1 index:0 type:<root>.Fn<kotlin.String, kotlin.Int>
+      VALUE_PARAMETER name:f2 index:1 type:<root>.Fn<kotlin.Int, kotlin.String>
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J'
+          CALL 'public abstract fun run (s: kotlin.String, i: kotlin.Int, t: T of <root>.Fn): R of <root>.Fn declared in <root>.Fn' type=kotlin.Int origin=null
+            $this: GET_VAR 'f1: <root>.Fn<kotlin.String, kotlin.Int> declared in <root>.J.runConversion' type=<root>.Fn<kotlin.String, kotlin.Int> origin=null
+            s: CONST String type=kotlin.String value="Bar"
+            i: CONST Int type=kotlin.Int value=1
+            t: CALL 'public abstract fun run (s: kotlin.String, i: kotlin.Int, t: T of <root>.Fn): R of <root>.Fn declared in <root>.Fn' type=kotlin.String origin=null
+              $this: GET_VAR 'f2: <root>.Fn<kotlin.Int, kotlin.String> declared in <root>.J.runConversion' type=<root>.Fn<kotlin.Int, kotlin.String> origin=null
+              s: CONST String type=kotlin.String value="Foo"
+              i: CONST Int type=kotlin.Int value=42
+              t: CONST Int type=kotlin.Int value=239
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  PROPERTY name:fsi visibility:public modality:FINAL [val]
+    FIELD PROPERTY_BACKING_FIELD name:fsi type:<root>.Fn<kotlin.String, kotlin.Int> visibility:private [final,static]
+      EXPRESSION_BODY
+        BLOCK type=<root>.fsi.<no name provided> origin=OBJECT_LITERAL
+          CLASS CLASS name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.String, kotlin.Int>]
+            $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.fsi.<no name provided>
+            CONSTRUCTOR visibility:public <> () returnType:<root>.fsi.<no name provided> [primary]
+              BLOCK_BODY
+                DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+                INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.String, kotlin.Int>]'
+            FUN name:run visibility:public modality:OPEN <> ($this:<root>.fsi.<no name provided>, s:kotlin.String, i:kotlin.Int, t:kotlin.String) returnType:kotlin.Int
+              overridden:
+                public abstract fun run (s: kotlin.String, i: kotlin.Int, t: T of <root>.Fn): R of <root>.Fn declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:<root>.fsi.<no name provided>
+              VALUE_PARAMETER name:s index:0 type:kotlin.String
+              VALUE_PARAMETER name:i index:1 type:kotlin.Int
+              VALUE_PARAMETER name:t index:2 type:kotlin.String
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='public open fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.String): kotlin.Int declared in <root>.fsi.<no name provided>'
+                  CONST Int type=kotlin.Int value=1
+            FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+              overridden:
+                public open fun equals (other: kotlin.Any?): kotlin.Boolean [fake_override,operator] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+              VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+            FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+              overridden:
+                public open fun hashCode (): kotlin.Int [fake_override] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+            FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+              overridden:
+                public open fun toString (): kotlin.String [fake_override] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+          CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in <root>.fsi.<no name provided>' type=<root>.fsi.<no name provided> origin=OBJECT_LITERAL
+    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-fsi> visibility:public modality:FINAL <> () returnType:<root>.Fn<kotlin.String, kotlin.Int>
+      correspondingProperty: PROPERTY name:fsi visibility:public modality:FINAL [val]
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun <get-fsi> (): <root>.Fn<kotlin.String, kotlin.Int> declared in <root>'
+          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:fsi type:<root>.Fn<kotlin.String, kotlin.Int> visibility:private [final,static]' type=<root>.Fn<kotlin.String, kotlin.Int> origin=null
+  PROPERTY name:fis visibility:public modality:FINAL [val]
+    FIELD PROPERTY_BACKING_FIELD name:fis type:<root>.Fn<kotlin.Int, kotlin.String> visibility:private [final,static]
+      EXPRESSION_BODY
+        BLOCK type=<root>.fis.<no name provided> origin=OBJECT_LITERAL
+          CLASS CLASS name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.Int, kotlin.String>]
+            $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.fis.<no name provided>
+            CONSTRUCTOR visibility:public <> () returnType:<root>.fis.<no name provided> [primary]
+              BLOCK_BODY
+                DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any'
+                INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:<no name provided> modality:FINAL visibility:local superTypes:[<root>.Fn<kotlin.Int, kotlin.String>]'
+            FUN name:run visibility:public modality:OPEN <> ($this:<root>.fis.<no name provided>, s:kotlin.String, i:kotlin.Int, t:kotlin.Int) returnType:kotlin.String
+              overridden:
+                public abstract fun run (s: kotlin.String, i: kotlin.Int, t: T of <root>.Fn): R of <root>.Fn declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:<root>.fis.<no name provided>
+              VALUE_PARAMETER name:s index:0 type:kotlin.String
+              VALUE_PARAMETER name:i index:1 type:kotlin.Int
+              VALUE_PARAMETER name:t index:2 type:kotlin.Int
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='public open fun run (s: kotlin.String, i: kotlin.Int, t: kotlin.Int): kotlin.String declared in <root>.fis.<no name provided>'
+                  CONST String type=kotlin.String value=""
+            FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+              overridden:
+                public open fun equals (other: kotlin.Any?): kotlin.Boolean [fake_override,operator] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+              VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+            FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+              overridden:
+                public open fun hashCode (): kotlin.Int [fake_override] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+            FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+              overridden:
+                public open fun toString (): kotlin.String [fake_override] declared in <root>.Fn
+              $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+          CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in <root>.fis.<no name provided>' type=<root>.fis.<no name provided> origin=OBJECT_LITERAL
+    FUN DEFAULT_PROPERTY_ACCESSOR name:<get-fis> visibility:public modality:FINAL <> () returnType:<root>.Fn<kotlin.Int, kotlin.String>
+      correspondingProperty: PROPERTY name:fis visibility:public modality:FINAL [val]
+      BLOCK_BODY
+        RETURN type=kotlin.Nothing from='public final fun <get-fis> (): <root>.Fn<kotlin.Int, kotlin.String> declared in <root>'
+          GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:fis type:<root>.Fn<kotlin.Int, kotlin.String> visibility:private [final,static]' type=<root>.Fn<kotlin.Int, kotlin.String> origin=null
+  FUN name:test visibility:public modality:FINAL <> (j:<root>.J) returnType:kotlin.Unit
+    VALUE_PARAMETER name:j index:0 type:<root>.J
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        CALL 'public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J' type=kotlin.Int origin=null
+          $this: GET_VAR 'j: <root>.J declared in <root>.test' type=<root>.J origin=null
+          f1: CALL 'public final fun <get-fsi> (): <root>.Fn<kotlin.String, kotlin.Int> declared in <root>' type=<root>.Fn<kotlin.String, kotlin.Int> origin=GET_PROPERTY
+          f2: TYPE_OP type=<root>.Fn<kotlin.Int, kotlin.String> origin=SAM_CONVERSION typeOperand=<root>.Fn<kotlin.Int, kotlin.String>
+            FUN_EXPR type=kotlin.Function3<@[ParameterName(name = 's')] kotlin.String, @[ParameterName(name = 'i')] kotlin.Int, @[ParameterName(name = 't')] kotlin.Int, kotlin.String> origin=LAMBDA
+              FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> (s:kotlin.String, i:kotlin.Int, ti:kotlin.Int) returnType:kotlin.String
+                VALUE_PARAMETER name:s index:0 type:kotlin.String
+                VALUE_PARAMETER name:i index:1 type:kotlin.Int
+                VALUE_PARAMETER name:ti index:2 type:kotlin.Int
+                BLOCK_BODY
+                  RETURN type=kotlin.Nothing from='local final fun <anonymous> (s: kotlin.String, i: kotlin.Int, ti: kotlin.Int): kotlin.String declared in <root>.test'
+                    CONST String type=kotlin.String value=""
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        CALL 'public final fun runConversion (f1: <root>.Fn<kotlin.String, kotlin.Int>, f2: <root>.Fn<kotlin.Int, kotlin.String>): kotlin.Int declared in <root>.J' type=kotlin.Int origin=null
+          $this: GET_VAR 'j: <root>.J declared in <root>.test' type=<root>.J origin=null
+          f1: TYPE_OP type=<root>.Fn<kotlin.String, kotlin.Int> origin=SAM_CONVERSION typeOperand=<root>.Fn<kotlin.String, kotlin.Int>
+            FUN_EXPR type=kotlin.Function3<@[ParameterName(name = 's')] kotlin.String, @[ParameterName(name = 'i')] kotlin.Int, @[ParameterName(name = 't')] kotlin.String, kotlin.Int> origin=LAMBDA
+              FUN LOCAL_FUNCTION_FOR_LAMBDA name:<anonymous> visibility:local modality:FINAL <> (s:kotlin.String, i:kotlin.Int, ts:kotlin.String) returnType:kotlin.Int
+                VALUE_PARAMETER name:s index:0 type:kotlin.String
+                VALUE_PARAMETER name:i index:1 type:kotlin.Int
+                VALUE_PARAMETER name:ts index:2 type:kotlin.String
+                BLOCK_BODY
+                  RETURN type=kotlin.Nothing from='local final fun <anonymous> (s: kotlin.String, i: kotlin.Int, ts: kotlin.String): kotlin.Int declared in <root>.test'
+                    CONST Int type=kotlin.Int value=1
+          f2: CALL 'public final fun <get-fis> (): <root>.Fn<kotlin.Int, kotlin.String> declared in <root>' type=<root>.Fn<kotlin.Int, kotlin.String> origin=GET_PROPERTY
diff --git a/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.fir.txt b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.fir.txt
new file mode 100644
index 00000000000..6febaf26279
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.fir.txt
@@ -0,0 +1,113 @@
+FILE fqName:<root> fileName:/samConversionsWithSmartCasts.kt
+  CLASS INTERFACE name:KRunnable modality:ABSTRACT visibility:public superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.KRunnable
+    FUN name:run visibility:public modality:ABSTRACT <> ($this:<root>.KRunnable) returnType:kotlin.Unit
+      $this: VALUE_PARAMETER name:<this> type:<root>.KRunnable
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:id visibility:public modality:FINAL <T> (x:T of <root>.id) returnType:T of <root>.id
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?]
+    VALUE_PARAMETER name:x index:0 type:T of <root>.id
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun id <T> (x: T of <root>.id): T of <root>.id declared in <root>'
+        GET_VAR 'x: T of <root>.id declared in <root>.id' type=T of <root>.id origin=null
+  FUN name:run1 visibility:public modality:FINAL <> (r:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:r index:0 type:<root>.KRunnable
+    BLOCK_BODY
+  FUN name:run2 visibility:public modality:FINAL <> (r1:<root>.KRunnable, r2:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:r1 index:0 type:<root>.KRunnable
+    VALUE_PARAMETER name:r2 index:1 type:<root>.KRunnable
+    BLOCK_BODY
+  FUN name:test0 visibility:public modality:FINAL <T> (a:T of <root>.test0) returnType:kotlin.Unit
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[<root>.KRunnable; kotlin.Function0<kotlin.Unit>]
+    VALUE_PARAMETER name:a index:0 type:T of <root>.test0
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: GET_VAR 'a: T of <root>.test0 declared in <root>.test0' type=T of <root>.test0 origin=null
+  FUN name:test1 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test1' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+            r: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test1' type=<root>.KRunnable origin=null
+  FUN name:test2 visibility:public modality:FINAL <> (a:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:<root>.KRunnable
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+        GET_VAR 'a: <root>.KRunnable declared in <root>.test2' type=<root>.KRunnable origin=null
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: GET_VAR 'a: <root>.KRunnable declared in <root>.test2' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test3 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: CALL 'public final fun run2 (r1: <root>.KRunnable, r2: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+            r1: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=<root>.KRunnable origin=null
+            r2: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=<root>.KRunnable origin=null
+  FUN name:test4 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>, b:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    VALUE_PARAMETER name:b index:1 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: CALL 'public final fun run2 (r1: <root>.KRunnable, r2: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+            r1: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=<root>.KRunnable origin=null
+            r2: GET_VAR 'b: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test5 visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Any declared in <root>.test5' type=kotlin.Any origin=null
+          then: CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+            r: GET_VAR 'a: kotlin.Any declared in <root>.test5' type=<root>.KRunnable origin=null
+  FUN name:test5x visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=kotlin.Any origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+              GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=<root>.KRunnable origin=null
+            CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r: GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=<root>.KRunnable origin=null
+  FUN name:test6 visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+        GET_VAR 'a: kotlin.Any declared in <root>.test6' type=kotlin.Any origin=null
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: GET_VAR 'a: kotlin.Any declared in <root>.test6' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test8 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: CALL 'public final fun id <T> (x: T of <root>.id): T of <root>.id declared in <root>' type=kotlin.Function0<kotlin.Unit> origin=null
+          <T>: kotlin.Function0<kotlin.Unit>
+          x: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test8' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test9 visibility:public modality:FINAL <> () returnType:kotlin.Unit
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: FUNCTION_REFERENCE 'public final fun test9 (): kotlin.Unit declared in <root>' type=kotlin.reflect.KFunction0<kotlin.Unit> origin=null
diff --git a/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt
new file mode 100644
index 00000000000..5a09bc36b7c
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt
@@ -0,0 +1,83 @@
+// !LANGUAGE: +NewInference +FunctionalInterfaceConversion +SamConversionPerArgument +SamConversionForKotlinFunctions
+fun interface KRunnable {
+    fun run()
+}
+
+fun <T> id(x: T) = x
+
+fun run1(r: KRunnable) {}
+fun run2(r1: KRunnable, r2: KRunnable) {}
+
+fun <T> test0(a: T) where T : KRunnable, T : () -> Unit {
+    run1(a)
+}
+
+fun test1(a: () -> Unit) {
+    if (a is KRunnable) {
+        run1(a)
+    }
+}
+
+fun test2(a: KRunnable) {
+    a as () -> Unit
+    run1(a)
+}
+
+fun test3(a: () -> Unit) {
+    if (a is KRunnable) {
+        run2(a, a)
+    }
+}
+
+fun test4(a: () -> Unit, b: () -> Unit) {
+    if (a is KRunnable) {
+        run2(a, b)
+    }
+}
+
+fun test5(a: Any) {
+    if (a is KRunnable) {
+        run1(a)
+    }
+}
+
+fun test5x(a: Any) {
+    if (a is KRunnable) {
+        a as () -> Unit
+        run1(a)
+    }
+}
+
+fun test6(a: Any) {
+    a as () -> Unit
+    run1(a)
+}
+
+// TODO see KT-36013
+//fun test7(a: (Int) -> Int) {
+//    a as () -> Unit
+//    run1(a)
+//}
+//
+//fun <T : (Int) -> Int> test7a(a: T) {
+//    a as () -> Unit
+//    run1(a)
+//}
+//
+//fun <T> test7b(a: T) where T : (Int) -> Int, T : () -> Unit {
+//    run1(a)
+//}
+//
+//interface Unrelated
+//
+//fun <T> test7c(a: T) where T : Unrelated, T : () -> Unit {
+//    run1(a)
+//}
+
+fun test8(a: () -> Unit) {
+    run1(id(a))
+}
+
+fun test9() {
+    run1(::test9)
+}
diff --git a/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.txt b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.txt
new file mode 100644
index 00000000000..3a6b016ee1d
--- /dev/null
+++ b/compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.txt
@@ -0,0 +1,131 @@
+FILE fqName:<root> fileName:/samConversionsWithSmartCasts.kt
+  CLASS INTERFACE name:KRunnable modality:ABSTRACT visibility:public [fun] superTypes:[kotlin.Any]
+    $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.KRunnable
+    FUN name:run visibility:public modality:ABSTRACT <> ($this:<root>.KRunnable) returnType:kotlin.Unit
+      $this: VALUE_PARAMETER name:<this> type:<root>.KRunnable
+    FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
+      overridden:
+        public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+      VALUE_PARAMETER name:other index:0 type:kotlin.Any?
+    FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override]
+      overridden:
+        public open fun hashCode (): kotlin.Int declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+    FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override]
+      overridden:
+        public open fun toString (): kotlin.String declared in kotlin.Any
+      $this: VALUE_PARAMETER name:<this> type:kotlin.Any
+  FUN name:id visibility:public modality:FINAL <T> (x:T of <root>.id) returnType:T of <root>.id
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[kotlin.Any?]
+    VALUE_PARAMETER name:x index:0 type:T of <root>.id
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='public final fun id <T> (x: T of <root>.id): T of <root>.id declared in <root>'
+        GET_VAR 'x: T of <root>.id declared in <root>.id' type=T of <root>.id origin=null
+  FUN name:run1 visibility:public modality:FINAL <> (r:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:r index:0 type:<root>.KRunnable
+    BLOCK_BODY
+  FUN name:run2 visibility:public modality:FINAL <> (r1:<root>.KRunnable, r2:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:r1 index:0 type:<root>.KRunnable
+    VALUE_PARAMETER name:r2 index:1 type:<root>.KRunnable
+    BLOCK_BODY
+  FUN name:test0 visibility:public modality:FINAL <T> (a:T of <root>.test0) returnType:kotlin.Unit
+    TYPE_PARAMETER name:T index:0 variance: superTypes:[<root>.KRunnable; kotlin.Function0<kotlin.Unit>]
+    VALUE_PARAMETER name:a index:0 type:T of <root>.test0
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: GET_VAR 'a: T of <root>.test0 declared in <root>.test0' type=T of <root>.test0 origin=null
+  FUN name:test1 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test1' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test1' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test2 visibility:public modality:FINAL <> (a:<root>.KRunnable) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:<root>.KRunnable
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+          GET_VAR 'a: <root>.KRunnable declared in <root>.test2' type=<root>.KRunnable origin=null
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: GET_VAR 'a: <root>.KRunnable declared in <root>.test2' type=<root>.KRunnable origin=null
+  FUN name:test3 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            CALL 'public final fun run2 (r1: <root>.KRunnable, r2: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r1: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=kotlin.Function0<kotlin.Unit> origin=null
+              r2: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test3' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test4 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>, b:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    VALUE_PARAMETER name:b index:1 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=kotlin.Function0<kotlin.Unit> origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            CALL 'public final fun run2 (r1: <root>.KRunnable, r2: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r1: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=kotlin.Function0<kotlin.Unit> origin=null
+              r2: TYPE_OP type=<root>.KRunnable origin=SAM_CONVERSION typeOperand=<root>.KRunnable
+                GET_VAR 'b: kotlin.Function0<kotlin.Unit> declared in <root>.test4' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test5 visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Any declared in <root>.test5' type=kotlin.Any origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Any declared in <root>.test5' type=kotlin.Any origin=null
+  FUN name:test5x visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      WHEN type=kotlin.Unit origin=IF
+        BRANCH
+          if: TYPE_OP type=kotlin.Boolean origin=INSTANCEOF typeOperand=<root>.KRunnable
+            GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=kotlin.Any origin=null
+          then: BLOCK type=kotlin.Unit origin=null
+            TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+              TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+                GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=kotlin.Any origin=null
+            CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+              r: TYPE_OP type=<root>.KRunnable origin=IMPLICIT_CAST typeOperand=<root>.KRunnable
+                GET_VAR 'a: kotlin.Any declared in <root>.test5x' type=kotlin.Any origin=null
+  FUN name:test6 visibility:public modality:FINAL <> (a:kotlin.Any) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Any
+    BLOCK_BODY
+      TYPE_OP type=kotlin.Unit origin=IMPLICIT_COERCION_TO_UNIT typeOperand=kotlin.Unit
+        TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=CAST typeOperand=kotlin.Function0<kotlin.Unit>
+          GET_VAR 'a: kotlin.Any declared in <root>.test6' type=kotlin.Any origin=null
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: TYPE_OP type=<root>.KRunnable origin=SAM_CONVERSION typeOperand=<root>.KRunnable
+          TYPE_OP type=kotlin.Function0<kotlin.Unit> origin=IMPLICIT_CAST typeOperand=kotlin.Function0<kotlin.Unit>
+            GET_VAR 'a: kotlin.Any declared in <root>.test6' type=kotlin.Any origin=null
+  FUN name:test8 visibility:public modality:FINAL <> (a:kotlin.Function0<kotlin.Unit>) returnType:kotlin.Unit
+    VALUE_PARAMETER name:a index:0 type:kotlin.Function0<kotlin.Unit>
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: TYPE_OP type=<root>.KRunnable origin=SAM_CONVERSION typeOperand=<root>.KRunnable
+          CALL 'public final fun id <T> (x: T of <root>.id): T of <root>.id declared in <root>' type=kotlin.Function0<kotlin.Unit> origin=null
+            <T>: kotlin.Function0<kotlin.Unit>
+            x: GET_VAR 'a: kotlin.Function0<kotlin.Unit> declared in <root>.test8' type=kotlin.Function0<kotlin.Unit> origin=null
+  FUN name:test9 visibility:public modality:FINAL <> () returnType:kotlin.Unit
+    BLOCK_BODY
+      CALL 'public final fun run1 (r: <root>.KRunnable): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
+        r: TYPE_OP type=<root>.KRunnable origin=SAM_CONVERSION typeOperand=<root>.KRunnable
+          FUNCTION_REFERENCE 'public final fun test9 (): kotlin.Unit declared in <root>' type=kotlin.reflect.KFunction0<kotlin.Unit> origin=null
diff --git a/compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java b/compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java
index 21b62e692f4..df7dad6883e 100644
--- a/compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/ir/IrTextTestCaseGenerated.java
@@ -1419,6 +1419,39 @@ public class IrTextTestCaseGenerated extends AbstractIrTextTestCase {
             }
         }
 
+        @TestMetadata("compiler/testData/ir/irText/expressions/funInterface")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class FunInterface extends AbstractIrTextTestCase {
+            private void runTest(String testDataFilePath) throws Exception {
+                KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+            }
+
+            public void testAllFilesPresentInFunInterface() throws Exception {
+                KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/ir/irText/expressions/funInterface"), Pattern.compile("^(.+)\\.kt$"), null, true);
+            }
+
+            @TestMetadata("basicFunInterfaceConversion.kt")
+            public void testBasicFunInterfaceConversion() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/basicFunInterfaceConversion.kt");
+            }
+
+            @TestMetadata("castFromAny.kt")
+            public void testCastFromAny() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/castFromAny.kt");
+            }
+
+            @TestMetadata("partialSam.kt")
+            public void testPartialSam() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/partialSam.kt");
+            }
+
+            @TestMetadata("samConversionsWithSmartCasts.kt")
+            public void testSamConversionsWithSmartCasts() throws Exception {
+                runTest("compiler/testData/ir/irText/expressions/funInterface/samConversionsWithSmartCasts.kt");
+            }
+        }
+
         @TestMetadata("compiler/testData/ir/irText/expressions/sam")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)
diff --git a/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt b/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt
index d97b96f41ca..cf77c0eaf00 100644
--- a/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt
+++ b/compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt
@@ -22,7 +22,7 @@ fun String.parseKonanAbiVersion(): KotlinAbiVersion {
 
 data class KotlinAbiVersion(val version: Int) {
     companion object {
-        val CURRENT = KotlinAbiVersion(23)
+        val CURRENT = KotlinAbiVersion(24)
     }
 
     override fun toString() = "$version"