Support toString for AdaptedFunctionReference subclasses

Also make it serializable like other lambdas, suspend lambdas and normal
callable references.

compiler/backend/src/org/jetbrains/kotlin/codegen/JvmRuntimeTypes.kt

@@ -147,7 +147,7 @@ class JvmRuntimeTypes(
                 ?: referencedFunction.dispatchReceiverParameter?.type,
             anonymousFunctionDescriptor.valueParameters.drop(receivers).map { it.type },
             null,
-            referencedFunction.returnType!!,
+            anonymousFunctionDescriptor.returnType!!,
             referencedFunction.isSuspend
         )
 

compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java

@@ -2090,6 +2090,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleEmptyVararg.kt");
             }
 
+            @TestMetadata("toString.kt")
+            public void testToString() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/toString.kt");
+            }
+
             @TestMetadata("unboundReferences.kt")
             public void testUnboundReferences() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/unboundReferences.kt");
@@ -2917,6 +2922,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
                 KotlinTestUtils.runTestWithCustomIgnoreDirective(this::doTest, TargetBackend.JVM_IR, testDataFilePath, "// IGNORE_BACKEND_FIR: ");
             }
 
+            @TestMetadata("adaptedReferences.kt")
+            public void testAdaptedReferences() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/serializability/adaptedReferences.kt");
+            }
+
             public void testAllFilesPresentInSerializability() throws Exception {
                 KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/callableReference/serializability"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
             }

compiler/testData/codegen/box/callableReference/adaptedReferences/toString.kt

@@ -0,0 +1,27 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
+// WITH_RUNTIME
+
+import kotlin.test.assertEquals
+
+class A {
+    fun foo(s: String = "", vararg xs: Long): CharSequence = "foo"
+}
+
+fun check(expected: String, x: Any) {
+    assertEquals(expected, x.toString())
+}
+
+fun coercionToUnit(f: (A, String, LongArray) -> Unit): Any = f
+fun varargToElement(f: (A, String, Long, Long) -> CharSequence): Any = f
+fun defaultAndVararg(f: (A) -> CharSequence): Any = f
+fun allOfTheAbove(f: (A) -> Unit): Any = f
+
+fun box(): String {
+    check("Function3<A, java.lang.String, long[], kotlin.Unit>", coercionToUnit(A::foo))
+    check("Function4<A, java.lang.String, java.lang.Long, java.lang.Long, java.lang.CharSequence>", varargToElement(A::foo))
+    check("Function1<A, java.lang.CharSequence>", defaultAndVararg(A::foo))
+    check("Function1<A, kotlin.Unit>", allOfTheAbove(A::foo))
+
+    return "OK"
+}

compiler/testData/codegen/box/callableReference/serializability/adaptedReferences.kt

@@ -0,0 +1,36 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND_FIR: JVM_IR
+// WITH_REFLECT
+
+import java.io.*
+import kotlin.test.assertEquals
+
+class A {
+    fun foo(s: String = "", vararg xs: Long): String = "foo"
+}
+
+fun check(x: Any) {
+    val baos = ByteArrayOutputStream()
+    val oos = ObjectOutputStream(baos)
+    oos.writeObject(x)
+    oos.close()
+
+    val bais = ByteArrayInputStream(baos.toByteArray())
+    val ois = ObjectInputStream(bais)
+    assertEquals(x, ois.readObject())
+    ois.close()
+}
+
+fun coercionToUnit(f: (A, String, LongArray) -> Unit): Any = f
+fun varargToElement(f: (A, String, Long, Long) -> String): Any = f
+fun defaultAndVararg(f: (A) -> String): Any = f
+fun allOfTheAbove(f: (A) -> Unit): Any = f
+
+fun box(): String {
+    check(coercionToUnit(A::foo))
+    check(varargToElement(A::foo))
+    check(defaultAndVararg(A::foo))
+    check(allOfTheAbove(A::foo))
+
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -2110,6 +2110,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleEmptyVararg.kt");
             }
 
+            @TestMetadata("toString.kt")
+            public void testToString() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/toString.kt");
+            }
+
             @TestMetadata("unboundReferences.kt")
             public void testUnboundReferences() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/unboundReferences.kt");
@@ -2937,6 +2942,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 KotlinTestUtils.runTest(this::doTest, TargetBackend.JVM, testDataFilePath);
             }
 
+            @TestMetadata("adaptedReferences.kt")
+            public void testAdaptedReferences() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/serializability/adaptedReferences.kt");
+            }
+
             public void testAllFilesPresentInSerializability() throws Exception {
                 KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/callableReference/serializability"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM, true);
             }

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -2110,6 +2110,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleEmptyVararg.kt");
             }
 
+            @TestMetadata("toString.kt")
+            public void testToString() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/toString.kt");
+            }
+
             @TestMetadata("unboundReferences.kt")
             public void testUnboundReferences() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/unboundReferences.kt");
@@ -2937,6 +2942,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 KotlinTestUtils.runTest(this::doTest, TargetBackend.JVM, testDataFilePath);
             }
 
+            @TestMetadata("adaptedReferences.kt")
+            public void testAdaptedReferences() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/serializability/adaptedReferences.kt");
+            }
+
             public void testAllFilesPresentInSerializability() throws Exception {
                 KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/callableReference/serializability"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM, true);
             }

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -2090,6 +2090,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/simpleEmptyVararg.kt");
             }
 
+            @TestMetadata("toString.kt")
+            public void testToString() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/toString.kt");
+            }
+
             @TestMetadata("unboundReferences.kt")
             public void testUnboundReferences() throws Exception {
                 runTest("compiler/testData/codegen/box/callableReference/adaptedReferences/unboundReferences.kt");
@@ -2917,6 +2922,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 KotlinTestUtils.runTest(this::doTest, TargetBackend.JVM_IR, testDataFilePath);
             }
 
+            @TestMetadata("adaptedReferences.kt")
+            public void testAdaptedReferences() throws Exception {
+                runTest("compiler/testData/codegen/box/callableReference/serializability/adaptedReferences.kt");
+            }
+
             public void testAllFilesPresentInSerializability() throws Exception {
                 KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/codegen/box/callableReference/serializability"), Pattern.compile("^(.+)\\.kt$"), null, TargetBackend.JVM_IR, true);
             }

libraries/stdlib/jvm/runtime/kotlin/jvm/internal/AdaptedFunctionReference.java

@@ -8,6 +8,8 @@ package kotlin.jvm.internal;
 import kotlin.SinceKotlin;
 import kotlin.reflect.KDeclarationContainer;
 
+import java.io.Serializable;
+
 import static kotlin.jvm.internal.CallableReference.NO_RECEIVER;
 
 /**
@@ -24,7 +26,7 @@ import static kotlin.jvm.internal.CallableReference.NO_RECEIVER;
  */
 @SuppressWarnings({"rawtypes", "WeakerAccess", "unused"})
 @SinceKotlin(version = "1.4")
-public class AdaptedFunctionReference {
+public class AdaptedFunctionReference implements FunctionBase, Serializable {
     protected final Object receiver;
     private final Class owner;
     private final String name;
@@ -47,6 +49,11 @@ public class AdaptedFunctionReference {
         this.flags = flags >> 1;
     }
 
+    @Override
+    public int getArity() {
+        return arity;
+    }
+
     public KDeclarationContainer getOwner() {
         return owner == null ? null :
                isTopLevel ? Reflection.getOrCreateKotlinPackage(owner) : Reflection.getOrCreateKotlinClass(owner);
@@ -77,4 +84,9 @@ public class AdaptedFunctionReference {
         result = result * 31 + flags;
         return result;
     }
+
+    @Override
+    public String toString() {
+        return Reflection.renderLambdaToString(this);
+    }
 }

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib-runtime-merged.txt

@@ -3180,13 +3180,15 @@ public abstract interface class kotlin/jvm/functions/FunctionN : kotlin/Function
 	public abstract fun invoke ([Ljava/lang/Object;)Ljava/lang/Object;
 }
 
-public class kotlin/jvm/internal/AdaptedFunctionReference {
+public class kotlin/jvm/internal/AdaptedFunctionReference : java/io/Serializable, kotlin/jvm/internal/FunctionBase {
 	protected final field receiver Ljava/lang/Object;
 	public fun <init> (ILjava/lang/Class;Ljava/lang/String;Ljava/lang/String;I)V
 	public fun <init> (ILjava/lang/Object;Ljava/lang/Class;Ljava/lang/String;Ljava/lang/String;I)V
 	public fun equals (Ljava/lang/Object;)Z
+	public fun getArity ()I
 	public fun getOwner ()Lkotlin/reflect/KDeclarationContainer;
 	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
 }
 
 public final class kotlin/jvm/internal/ArrayIteratorKt {