[IR] Supported conversions to fun interfaces

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/KonanLoweringPhases.kt

@@ -199,11 +199,17 @@ internal val dataClassesPhase = makeKonanFileLoweringPhase(
         description = "Data classes lowering"
 )
 
+internal val singleAbstractMethodPhase = makeKonanFileLoweringPhase(
+        ::NativeSingleAbstractMethodLowering,
+        name = "SingleAbstractMethod",
+        description = "Replace SAM conversions with instances of interface-implementing classes"
+)
+
 internal val builtinOperatorPhase = makeKonanFileLoweringPhase(
         ::BuiltinOperatorLowering,
         name = "BuiltinOperators",
         description = "BuiltIn operators lowering",
-        prerequisite = setOf(defaultParameterExtentPhase)
+        prerequisite = setOf(defaultParameterExtentPhase, singleAbstractMethodPhase)
 )
 
 internal val finallyBlocksPhase = makeKonanFileLoweringPhase(

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ToplevelPhases.kt

@@ -19,8 +19,7 @@ import org.jetbrains.kotlin.backend.konan.serialization.*
 import org.jetbrains.kotlin.cli.common.messages.AnalyzerWithCompilerReport
 import org.jetbrains.kotlin.config.CommonConfigurationKeys
 import org.jetbrains.kotlin.config.languageVersionSettings
-import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
-import org.jetbrains.kotlin.descriptors.ModuleDescriptor
+import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.konan.isKonanStdlib
 import org.jetbrains.kotlin.ir.declarations.IrFile
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
@@ -329,6 +328,7 @@ internal val allLoweringsPhase = namedIrModulePhase(
                                 defaultParameterExtentPhase then
                                 innerClassPhase then
                                 dataClassesPhase then
+                                singleAbstractMethodPhase then
                                 builtinOperatorPhase then
                                 finallyBlocksPhase then
                                 testProcessorPhase then

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/NativeSingleAbstractMethodLowering.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package org.jetbrains.kotlin.backend.konan.lower
+
+import org.jetbrains.kotlin.backend.common.lower.SingleAbstractMethodLowering
+import org.jetbrains.kotlin.backend.konan.Context
+import org.jetbrains.kotlin.ir.types.IrType
+import org.jetbrains.kotlin.ir.types.classOrNull
+import org.jetbrains.kotlin.ir.types.defaultType
+import org.jetbrains.kotlin.ir.util.render
+
+internal class NativeSingleAbstractMethodLowering(context: Context) : SingleAbstractMethodLowering(context) {
+    override fun getSuperTypeForWrapper(typeOperand: IrType): IrType {
+        return typeOperand.classOrNull?.defaultType ?: error("Unsupported SAM conversion: ${typeOperand.render()}")
+    }
+}