Write metadata for suspend function into anonymous coroutine classes

To render nice Kotlin types in toString() of continuation

compiler/backend/src/org/jetbrains/kotlin/codegen/ClosureCodegen.java

@@ -250,7 +250,7 @@ public class ClosureCodegen extends MemberCodegen<KtElement> {
      * This is needed because once we're serializing this to a proto, there's no place to store information about external type parameters.
      */
     @NotNull
-    private static FunctionDescriptor createFreeLambdaDescriptor(@NotNull FunctionDescriptor descriptor) {
+    public static FunctionDescriptor createFreeLambdaDescriptor(@NotNull FunctionDescriptor descriptor) {
         FunctionDescriptor.CopyBuilder<? extends FunctionDescriptor> builder = descriptor.newCopyBuilder();
         List<TypeParameterDescriptor> typeParameters = new ArrayList<>(0);
         builder.setTypeParameters(typeParameters);

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineCodegen.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.codegen.*
 import org.jetbrains.kotlin.codegen.binding.CodegenBinding
 import org.jetbrains.kotlin.codegen.context.ClosureContext
 import org.jetbrains.kotlin.codegen.context.MethodContext
+import org.jetbrains.kotlin.codegen.serialization.JvmSerializerExtension
 import org.jetbrains.kotlin.coroutines.isSuspendLambda
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.annotations.Annotations
@@ -39,6 +40,7 @@ import org.jetbrains.kotlin.resolve.jvm.AsmTypes
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.OtherOrigin
 import org.jetbrains.kotlin.resolve.jvm.jvmSignature.JvmMethodSignature
+import org.jetbrains.kotlin.serialization.DescriptorSerializer
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.typeUtil.makeNullable
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
@@ -475,8 +477,10 @@ class CoroutineCodegenForNamedFunction private constructor(
     }
 
     override fun generateKotlinMetadataAnnotation() {
-        writeKotlinMetadata(v, state, KotlinClassHeader.Kind.SYNTHETIC_CLASS, 0) {
-            // Do not write method metadata for raw coroutine state machines
+        writeKotlinMetadata(v, state, KotlinClassHeader.Kind.SYNTHETIC_CLASS, 0) { av ->
+            val serializer = DescriptorSerializer.createForLambda(JvmSerializerExtension(v.serializationBindings, state))
+            val functionProto = serializer.functionProto(createFreeLambdaDescriptor(suspendFunctionJvmView)).build()
+            AsmUtil.writeAnnotationData(av, serializer, functionProto)
         }
     }
 

compiler/testData/codegen/box/coroutines/coroutineToString.kt

@@ -0,0 +1,33 @@
+// TARGET_BACKEND: JVM
+// WITH_REFLECT
+// WITH_COROUTINES
+
+import helpers.*
+import kotlin.coroutines.experimental.*
+import kotlin.coroutines.experimental.intrinsics.*
+
+class A<T : String> {
+    suspend fun foo() {}
+
+    suspend fun bar(): T {
+        foo()
+        return suspendCoroutineOrReturn { x ->
+            x.resume(x.toString() as T)
+            COROUTINE_SUSPENDED
+        }
+    }
+}
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(EmptyContinuation)
+}
+
+fun box(): String {
+    var result = ""
+
+    builder {
+        result = A<String>().bar()
+    }
+
+    return if (result == "(kotlin.coroutines.experimental.Continuation<T>) -> kotlin.Any?") "OK" else "Fail: $result"
+}

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

@@ -5018,6 +5018,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             doTest(fileName);
         }
 
+        @TestMetadata("coroutineToString.kt")
+        public void testCoroutineToString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/coroutineToString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("createCoroutineSafe.kt")
         public void testCreateCoroutineSafe() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/createCoroutineSafe.kt");

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

@@ -5018,6 +5018,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             doTest(fileName);
         }
 
+        @TestMetadata("coroutineToString.kt")
+        public void testCoroutineToString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/coroutineToString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("createCoroutineSafe.kt")
         public void testCreateCoroutineSafe() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/createCoroutineSafe.kt");

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

@@ -5018,6 +5018,12 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             doTest(fileName);
         }
 
+        @TestMetadata("coroutineToString.kt")
+        public void testCoroutineToString() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/coroutineToString.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("createCoroutineSafe.kt")
         public void testCreateCoroutineSafe() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/coroutines/createCoroutineSafe.kt");