fix(python): correctly handle structs out of callbacks

packages/jsii-calc/lib/compliance.ts

@@ -2396,3 +2396,17 @@ export class ConfusingToJackson {
 export interface ConfusingToJacksonStruct {
     readonly unionProperty?: Array<IFriendly | AbstractClass> | IFriendly;
 }
+
+/**
+ * Verifies that a "pure" implementation of an interface works correctly
+ */
+export interface IStructReturningDelegate {
+    returnStruct(): StructB;
+}
+export class ConsumePureInterface {
+    constructor(private readonly delegate: IStructReturningDelegate) { }
+
+    public workItBaby() {
+        return this.delegate.returnStruct();
+    }
+}

packages/jsii-calc/test/assembly.jsii

@@ -2533,6 +2533,49 @@
       ],
       "name": "Constructors"
     },
+    "jsii-calc.ConsumePureInterface": {
+      "assembly": "jsii-calc",
+      "docs": {
+        "stability": "experimental"
+      },
+      "fqn": "jsii-calc.ConsumePureInterface",
+      "initializer": {
+        "docs": {
+          "stability": "experimental"
+        },
+        "parameters": [
+          {
+            "name": "delegate",
+            "type": {
+              "fqn": "jsii-calc.IStructReturningDelegate"
+            }
+          }
+        ]
+      },
+      "kind": "class",
+      "locationInModule": {
+        "filename": "lib/compliance.ts",
+        "line": 2406
+      },
+      "methods": [
+        {
+          "docs": {
+            "stability": "experimental"
+          },
+          "locationInModule": {
+            "filename": "lib/compliance.ts",
+            "line": 2409
+          },
+          "name": "workItBaby",
+          "returns": {
+            "type": {
+              "fqn": "jsii-calc.StructB"
+            }
+          }
+        }
+      ],
+      "name": "ConsumePureInterface"
+    },
     "jsii-calc.ConsumerCanRingBell": {
       "assembly": "jsii-calc",
       "docs": {
@@ -5624,6 +5667,38 @@
         }
       ]
     },
+    "jsii-calc.IStructReturningDelegate": {
+      "assembly": "jsii-calc",
+      "docs": {
+        "stability": "experimental",
+        "summary": "Verifies that a \"pure\" implementation of an interface works correctly."
+      },
+      "fqn": "jsii-calc.IStructReturningDelegate",
+      "kind": "interface",
+      "locationInModule": {
+        "filename": "lib/compliance.ts",
+        "line": 2403
+      },
+      "methods": [
+        {
+          "abstract": true,
+          "docs": {
+            "stability": "experimental"
+          },
+          "locationInModule": {
+            "filename": "lib/compliance.ts",
+            "line": 2404
+          },
+          "name": "returnStruct",
+          "returns": {
+            "type": {
+              "fqn": "jsii-calc.StructB"
+            }
+          }
+        }
+      ],
+      "name": "IStructReturningDelegate"
+    },
     "jsii-calc.ImplementInternalInterface": {
       "assembly": "jsii-calc",
       "docs": {
@@ -11668,5 +11743,5 @@
     }
   },
   "version": "0.20.8",
-  "fingerprint": "s++IK3929zHRbg2MXmnn2A+PdvZnMVvPwaarJuUeBNM="
+  "fingerprint": "R5DFMiv/0riWRnreyHs899X53BbbVd5NTXmswDeF4/8="
 }

packages/jsii-dotnet-runtime-test/test/Amazon.JSII.Runtime.IntegrationTests/ComplianceTests.cs

@@ -1310,5 +1310,82 @@ public void CanObtainStructReferenceWithOverloadedSetters()
         {
             Assert.NotNull(ConfusingToJackson.MakeStructInstance());
         }
+
+        [Fact(DisplayName = Prefix + nameof(PureInterfacesCanBeUsedTransparently))]
+        public void PureInterfacesCanBeUsedTransparently()
+        {
+            var expected = new StructB { RequiredString = "It's Britney b**ch!" };
+            var del = new StructReturningDelegate(expected);
+            var consumer = new ConsumePureInterface(del);
+            Assert.Equal(expected.RequiredString, consumer.WorkItBaby().RequiredString);
+        }
+
+        private sealed class StructReturningDelegate: DeputyBase, IStructReturningDelegate
+        {
+            internal StructReturningDelegate(StructB expected)
+            {
+                Expected = expected;
+            }
+
+            private IStructB Expected { get; }
+
+            public IStructB ReturnStruct()
+            {
+                return Expected;
+            }
+        }
+
+        [Fact(DisplayName = Prefix + nameof(PureInterfacesCanBeUsedTransparently_WhenTransitivelyImplemented))]
+        public void PureInterfacesCanBeUsedTransparently_WhenTransitivelyImplemented()
+        {
+            var expected = new StructB { RequiredString = "It's Britney b**ch!" };
+            var del = new IndirectlyImplementsStructReturningDelegate(expected);
+            var consumer = new ConsumePureInterface(del);
+            Assert.Equal(expected.RequiredString, consumer.WorkItBaby().RequiredString);
+        }
+
+        private sealed class IndirectlyImplementsStructReturningDelegate : ImplementsStructReturningDelegate
+        {
+            internal IndirectlyImplementsStructReturningDelegate(StructB @struct) : base(@struct) {}
+        }
+
+        private class ImplementsStructReturningDelegate : DeputyBase, IStructReturningDelegate
+        {
+            private StructB Struct;
+
+            protected ImplementsStructReturningDelegate(StructB @struct)
+            {
+                this.Struct = @struct;
+            }
+
+            public IStructB ReturnStruct()
+            {
+                return Struct;
+            }
+        }
+
+        [Fact(DisplayName = Prefix + nameof(PureInterfacesCanBeUsedTransparently_WhenAddedToJsiiType))]
+        public void PureInterfacesCanBeUsedTransparently_WhenAddedToJsiiType()
+        {
+            var expected = new StructB { RequiredString = "It's Britney b**ch!" };
+            var del = new ImplementsAdditionalInterface(expected);
+            var consumer = new ConsumePureInterface(del);
+            Assert.Equal(expected.RequiredString, consumer.WorkItBaby().RequiredString);
+        }
+
+        private sealed class ImplementsAdditionalInterface : AllTypes, IStructReturningDelegate
+        {
+            private StructB Struct;
+
+            internal ImplementsAdditionalInterface(StructB @struct)
+            {
+                this.Struct = @struct;
+            }
+
+            public IStructB ReturnStruct()
+            {
+                return Struct;
+            }
+        }
     }
 }

packages/jsii-java-runtime-test/project/src/test/java/software/amazon/jsii/testing/ComplianceTest.java

@@ -1594,4 +1594,68 @@ public void canObtainReferenceWithOverloadedSetter() {
     public void canObtainStructReferenceWithOverloadedSetter() {
         assertNotNull(ConfusingToJackson.makeStructInstance());
     }
+
+    @Test
+    public void pureInterfacesCanBeUsedTransparently() {
+        final StructB expected = StructB.builder()
+            .requiredString("It's Britney b**ch!")
+            .build();
+        final IStructReturningDelegate delegate = new IStructReturningDelegate() {
+            public StructB returnStruct() {
+                return expected;
+            }
+        };
+        final ConsumePureInterface consumer = new ConsumePureInterface(delegate);
+        assertEquals(expected, consumer.workItBaby());
+    }
+
+    @Test
+    public void pureInterfacesCanBeUsedTransparently_WhenTransitivelyImplementing() {
+        final StructB expected = StructB.builder()
+            .requiredString("It's Britney b**ch!")
+            .build();
+        final IStructReturningDelegate delegate = new IndirectlyImplementsStructReturningDelegate(expected);
+        final ConsumePureInterface consumer = new ConsumePureInterface(delegate);
+        assertEquals(expected, consumer.workItBaby());
+    }
+
+    private static final class IndirectlyImplementsStructReturningDelegate extends ImplementsStructReturningDelegate {
+        public IndirectlyImplementsStructReturningDelegate(final StructB struct) {
+            super(struct);
+        }
+    }
+
+    private static class ImplementsStructReturningDelegate implements IStructReturningDelegate {
+        private final StructB struct;
+
+        protected ImplementsStructReturningDelegate(final StructB struct) {
+            this.struct = struct;
+        }
+
+        public StructB returnStruct() {
+            return this.struct;
+        }
+    }
+
+    @Test
+    public void interfacesCanBeUsedTransparently_WhenAddedToJsiiType() {
+        final StructB expected = StructB.builder()
+            .requiredString("It's Britney b**ch!")
+            .build();
+        final IStructReturningDelegate delegate = new ImplementsAdditionalInterface(expected);
+        final ConsumePureInterface consumer = new ConsumePureInterface(delegate);
+        assertEquals(expected, consumer.workItBaby());
+    }
+
+    private static final class ImplementsAdditionalInterface extends AllTypes implements IStructReturningDelegate {
+        private final StructB struct;
+
+        public ImplementsAdditionalInterface(final StructB struct) {
+            this.struct = struct;
+        }
+
+        public StructB returnStruct() {
+            return this.struct;
+        }
+    }
 }

packages/jsii-java-runtime-test/project/src/test/java/software/amazon/jsii/testing/JsiiClientTest.java

@@ -46,14 +46,14 @@ public void setUp() {
 
     @Test
     public void initialTest() {
-        JsiiObjectRef obj = client.createObject("@scope/jsii-calc-lib.Number", Collections.singletonList(42));
+        JsiiObjectRef obj = client.createObject("@scope/jsii-calc-lib.Number", Collections.singletonList(42), Arrays.asList(), Arrays.asList());
         assertEquals(84, fromSandbox(client.getPropertyValue(obj, "doubleValue")));
         assertEquals("Number", fromSandbox(client.callMethod(obj, "typeName", toSandboxArray())));
 
         ObjectNode calculatorProps = JSON.objectNode();
         calculatorProps.set("initialValue", JSON.numberNode(100));
 
-        JsiiObjectRef calculator = client.createObject("jsii-calc.Calculator", Collections.singletonList(calculatorProps));
+        JsiiObjectRef calculator = client.createObject("jsii-calc.Calculator", Collections.singletonList(calculatorProps), Arrays.asList(), Arrays.asList());
         assertNull(fromSandbox(client.callMethod(calculator, "add", toSandboxArray(50))));
 
         JsiiObjectRef add = JsiiObjectRef.parse(client.getPropertyValue(calculator, "curr"));
@@ -79,7 +79,7 @@ public void initialTest() {
 
     @Test
     public void asyncMethods() {
-        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods", Arrays.asList());
+        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods", Arrays.asList(), Arrays.asList(), Arrays.asList());
 
         // begin will return a promise
         JsiiPromise promise = client.beginAsyncMethod(obj, "callMe", toSandboxArray());
@@ -99,8 +99,7 @@ private Collection<JsiiOverride> methodOverride(final String methodName, final S
 
     @Test
     public void asyncMethodOverrides() {
-        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods",
-                Arrays.asList(), methodOverride("overrideMe", "myCookie"));
+        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods", Arrays.asList(), methodOverride("overrideMe", "myCookie"), Arrays.asList());
 
         // begin will return a promise
         JsiiPromise promise = client.beginAsyncMethod(obj, "callMe", toSandboxArray());
@@ -129,8 +128,7 @@ public void asyncMethodOverrides() {
 
     @Test
     public void asyncMethodOverridesThrow() {
-        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods",
-                Arrays.asList(), methodOverride("overrideMe", "myCookie"));
+        JsiiObjectRef obj = client.createObject("jsii-calc.AsyncVirtualMethods", Arrays.asList(), methodOverride("overrideMe", "myCookie"), Arrays.asList());
 
         // begin will return a promise
         JsiiPromise promise = client.beginAsyncMethod(obj, "callMe", toSandboxArray());
@@ -165,8 +163,7 @@ public void asyncMethodOverridesThrow() {
 
     @Test
     public void syncVirtualMethods() {
-        JsiiObjectRef obj = client.createObject("jsii-calc.SyncVirtualMethods",
-                Arrays.asList(), methodOverride("virtualMethod","myCookie"));
+        JsiiObjectRef obj = client.createObject("jsii-calc.SyncVirtualMethods", Arrays.asList(), methodOverride("virtualMethod","myCookie"), Arrays.asList());
 
         jsiiRuntime.setCallbackHandler(callback -> {
             assertEquals(obj.getObjId(), JsiiObjectRef.parse(callback.getInvoke().getObjref()).getObjId());
@@ -175,7 +172,7 @@ public void syncVirtualMethods() {
             assertEquals("myCookie", callback.getCookie());
 
             // interact with jsii from inside the callback
-            JsiiObjectRef num = client.createObject("@scope/jsii-calc-lib.Number", Arrays.asList(42));
+            JsiiObjectRef num = client.createObject("@scope/jsii-calc-lib.Number", Arrays.asList(42), Arrays.asList(), Arrays.asList());
             assertEquals(84, fromSandbox(client.getPropertyValue(num, "doubleValue")));
 
             return JSON.numberNode(898);
@@ -206,7 +203,7 @@ public void staticProperties() {
         JsonNode defaultInstance = client.getStaticPropertyValue(fqn, "instance");
         assertEquals("default", client.getPropertyValue(JsiiObjectRef.parse(defaultInstance), "value").textValue());
 
-        JsiiObjectRef newValue = client.createObject(fqn, Arrays.asList("NewValue"));
+        JsiiObjectRef newValue = client.createObject(fqn, Arrays.asList("NewValue"), Arrays.asList(), Arrays.asList());
         client.setStaticPropertyValue(fqn, "instance", newValue.toJson());
 
         JsonNode newInstance = client.getStaticPropertyValue(fqn, "instance");

packages/jsii-java-runtime/project/src/main/java/software/amazon/jsii/JsiiClient.java

@@ -56,16 +56,6 @@ public void loadModule(final JsiiModule module) {
         }
     }
 
-    /**
-     * Creates a remote jsii object.
-     * @param fqn The fully-qualified-name of the class.
-     * @param initializerArgs Constructor arguments.
-     * @return A jsii object reference.
-     */
-    public JsiiObjectRef createObject(final String fqn, final List<Object> initializerArgs) {
-        return createObject(fqn, initializerArgs, Collections.emptyList());
-    }
-
     /**
      * Creates a remote jsii object.
      * @param fqn The fully-qualified-name of the class.
@@ -77,12 +67,14 @@ public JsiiObjectRef createObject(final String fqn, final List<Object> initializ
      */
     public JsiiObjectRef createObject(final String fqn,
                                       final Collection<Object> initializerArgs,
-                                      final Collection<JsiiOverride> overrides) {
+                                      final Collection<JsiiOverride> overrides,
+                                      final Collection<String> interfaces) {
 
         CreateRequest request = new CreateRequest();
         request.setFqn(fqn);
         request.setArgs(initializerArgs);
         request.setOverrides(overrides);
+        request.setInterfaces(interfaces);
 
         ObjectNode req = JsiiObjectMapper.valueToTree(request);
         req.put("api", "create");