fix(kernel): Improve tagged type of wire values

packages/jsii-calc/lib/compliance.ts

@@ -1232,4 +1232,27 @@ export class JsiiAgent {
     public static get jsiiAgent(): string | undefined {
         return process.env.JSII_AGENT;
     }
-};
+};
+
+// Ensure the JSII kernel tags instances with the "most appropriate" FQN type label, so that runtimes are able to
+// correctly choose the implementation proxy that should be used. Failure to do so could cause situations where userland
+// needs to up-cast an instance to an incompatible type, which certain runtimes (such as Java) will prevent.
+// @See https://github.com/awslabs/jsii/issues/345
+export class PublicClass {
+    public hello(): void {}
+}
+export interface IPublicInterface {
+    bye(): void;
+}
+export class InbetweenClass extends PublicClass {}
+class PrivateClass extends InbetweenClass implements IPublicInterface {
+    public bye(): void {}
+}
+export class Constructors {
+    public static makeClass(): PublicClass {
+        return new PrivateClass();
+    }
+    public static makeInterface(): IPublicInterface {
+        return new PrivateClass();
+    }
+}

packages/jsii-calc/test/assembly.jsii

@@ -1098,6 +1098,31 @@
         }
       ]
     },
+    "jsii-calc.Constructors": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.Constructors",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "methods": [
+        {
+          "name": "makeClass",
+          "returns": {
+            "fqn": "jsii-calc.PublicClass"
+          },
+          "static": true
+        },
+        {
+          "name": "makeInterface",
+          "returns": {
+            "fqn": "jsii-calc.IPublicInterface"
+          },
+          "static": true
+        }
+      ],
+      "name": "Constructors"
+    },
     "jsii-calc.DefaultedConstructorArgument": {
       "assembly": "jsii-calc",
       "fqn": "jsii-calc.DefaultedConstructorArgument",
@@ -1675,6 +1700,18 @@
         }
       ]
     },
+    "jsii-calc.IPublicInterface": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.IPublicInterface",
+      "kind": "interface",
+      "methods": [
+        {
+          "abstract": true,
+          "name": "bye"
+        }
+      ],
+      "name": "IPublicInterface"
+    },
     "jsii-calc.IRandomNumberGenerator": {
       "assembly": "jsii-calc",
       "docs": {
@@ -1743,6 +1780,18 @@
         }
       ]
     },
+    "jsii-calc.InbetweenClass": {
+      "assembly": "jsii-calc",
+      "base": {
+        "fqn": "jsii-calc.PublicClass"
+      },
+      "fqn": "jsii-calc.InbetweenClass",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "name": "InbetweenClass"
+    },
     "jsii-calc.InterfaceImplementedByAbstractClass": {
       "assembly": "jsii-calc",
       "datatype": true,
@@ -2852,6 +2901,20 @@
         }
       ]
     },
+    "jsii-calc.PublicClass": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.PublicClass",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "methods": [
+        {
+          "name": "hello"
+        }
+      ],
+      "name": "PublicClass"
+    },
     "jsii-calc.ReferenceEnumFromScopedPackage": {
       "assembly": "jsii-calc",
       "docs": {
@@ -3762,5 +3825,5 @@
     }
   },
   "version": "0.7.13",
-  "fingerprint": "mc9Rni6GLgVDz8M6CGHapEiYbWsdEIl7CmBI0Qn+KXU="
+  "fingerprint": "WNp0Sw1d2+3FaQD0Fn01K4wYQi7Ms3w+NQatOylD1kM="
 }

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

@@ -874,6 +874,16 @@ public void ReceiveInstanceOfPrivateClass()
             Assert.True(new ReturnsPrivateImplementationOfInterface().PrivateImplementation.Success);
         }
 
+        [Fact(DisplayName = Prefix + nameof(ObjRefsAreLabelledUsingWithTheMostCorrectType))]
+        public void ObjRefsAreLabelledUsingWithTheMostCorrectType()
+        {
+            var classRef = Constructors.MakeClass();
+            var ifaceRef = Constructors.MakeInterface();
+
+            Assert.Equal(typeof(InbetweenClass), classRef.GetType());
+            Assert.NotEqual(typeof(InbetweenClass), ifaceRef.GetType());
+        }
+
         class NumberReturner : DeputyBase, IIReturnsNumber
         {
             public NumberReturner(double number)
@@ -1038,4 +1048,4 @@ public double Next()
             }
         }
     }
-}
+}

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

@@ -17,8 +17,10 @@
 import software.amazon.jsii.tests.calculator.GreetingAugmenter;
 import software.amazon.jsii.tests.calculator.IFriendlier;
 import software.amazon.jsii.tests.calculator.IFriendlyRandomGenerator;
+import software.amazon.jsii.tests.calculator.IPublicInterface;
 import software.amazon.jsii.tests.calculator.InterfaceWithProperties;
 import software.amazon.jsii.tests.calculator.IRandomNumberGenerator;
+import software.amazon.jsii.tests.calculator.InbetweenClass;
 import software.amazon.jsii.tests.calculator.InterfaceImplementedByAbstractClass;
 import software.amazon.jsii.tests.calculator.JSObjectLiteralForInterface;
 import software.amazon.jsii.tests.calculator.JSObjectLiteralToNative;
@@ -31,6 +33,7 @@
 import software.amazon.jsii.tests.calculator.NumberGenerator;
 import software.amazon.jsii.tests.calculator.Polymorphism;
 import software.amazon.jsii.tests.calculator.Power;
+import software.amazon.jsii.tests.calculator.PublicClass;
 import software.amazon.jsii.tests.calculator.ReferenceEnumFromScopedPackage;
 import software.amazon.jsii.tests.calculator.ReturnsPrivateImplementationOfInterface;
 import software.amazon.jsii.tests.calculator.Statics;
@@ -48,6 +51,8 @@
 import software.amazon.jsii.tests.calculator.lib.Value;
 import software.amazon.jsii.tests.calculator.JavaReservedWords;
 import software.amazon.jsii.tests.calculator.ClassWithPrivateConstructorAndAutomaticProperties;
+import software.amazon.jsii.tests.calculator.Constructors;
+
 import org.junit.Test;
 
 import java.io.IOException;
@@ -954,7 +959,7 @@ public void nullShouldBeTreatedAsUndefined() {
         obj.setChangeMeToUndefined(null);
         obj.verifyPropertyIsUndefined();
     }
-    
+
     @Test
     public void testJsiiAgent() {
         assertEquals("Java/" + System.getProperty("java.version"), JsiiAgent.getJsiiAgent());
@@ -968,6 +973,15 @@ public void receiveInstanceOfPrivateClass() {
         assertTrue(new ReturnsPrivateImplementationOfInterface().getPrivateImplementation().getSuccess());
     }
 
+    @Test
+    public void objRefsAreLabelledUsingWithTheMostCorrectType() {
+        final PublicClass classRef = Constructors.makeClass();
+        final IPublicInterface ifaceRef = Constructors.makeInterface();
+
+        assertTrue(classRef instanceof InbetweenClass);
+        assertTrue(ifaceRef instanceof IPublicInterface);
+    }
+
     static class MulTen extends Multiply {
         public MulTen(final int value) {
             super(new Number(value), new Number(10));

packages/jsii-kernel/lib/kernel.ts

@@ -961,7 +961,7 @@ export class Kernel {
             // have an object id, so we need to allocate one for it.
             this._debug('creating objref for', v);
             const fqn = this._fqnForObject(v);
-            if (!targetType || !spec.isNamedTypeReference(targetType) || fqn === targetType.fqn) {
+            if (!targetType || !spec.isNamedTypeReference(targetType) || this._isAssignable(fqn, targetType)) {
                 return this._createObjref(v, fqn);
             }
         }
@@ -1029,6 +1029,31 @@ export class Kernel {
         return v;
     }
 
+    /**
+     * Tests whether a given type (by it's FQN) can be assigned to a named type reference.
+     *
+     * @param actualTypeFqn the FQN of the type that is being tested.
+     * @param requiredType  the required reference type.
+     *
+     * @returns true if ``requiredType`` is a super-type (base class or implemented interface) of the type designated by
+     *          ``actualTypeFqn``.
+     */
+    private _isAssignable(actualTypeFqn: string, requiredType: spec.NamedTypeReference): boolean {
+        if (requiredType.fqn === actualTypeFqn) {
+            return true;
+        }
+        const actualType = this._typeInfoForFqn(actualTypeFqn);
+        if (spec.isClassType(actualType) && actualType.base) {
+            if (this._isAssignable(actualType.base.fqn, requiredType)) {
+                return true;
+            }
+        }
+        if (spec.isClassOrInterfaceType(actualType) && actualType.interfaces) {
+            return actualType.interfaces.find(iface => this._isAssignable(iface.fqn, requiredType)) != null;
+        }
+        return false;
+    }
+
     private _toSandboxValues(args: any[]) {
         return args.map(v => this._toSandbox(v));
     }

packages/jsii-kernel/test/test.kernel.ts

@@ -885,7 +885,7 @@ defineTest('object literals are returned by reference', async (test, sandbox) =>
 
     test.equal(newValue,
                sandbox.get({
-                   objref: sandbox.get({ objref, property: 'mutableObject' }).value,
+                   objref: sandbox.get({ objref, property: 'mutableObject' }).value,
                    property: 'value'
                }).value);
 
@@ -963,6 +963,16 @@ defineTest('JSII_AGENT is undefined in node.js', async (test, sandbox) => {
     test.equal(sandbox.sget({ fqn: 'jsii-calc.JsiiAgent', property: 'jsiiAgent' }).value, undefined);
 });
 
+defineTest('ObjRefs are labeled with the "most correct" type', async (test, sandbox) => {
+    const classRef = sandbox.sinvoke({ fqn: 'jsii-calc.Constructors', method: 'makeClass' }).result as api.ObjRef;
+    const ifaceRef = sandbox.sinvoke({ fqn: 'jsii-calc.Constructors', method: 'makeInterface' }).result as api.ObjRef;
+
+    test.ok(classRef[api.TOKEN_REF].startsWith('jsii-calc.InbetweenClass'),
+            `${classRef[api.TOKEN_REF]} starts with jsii-calc.InbetweenClass`);
+    test.ok(ifaceRef[api.TOKEN_REF].startsWith('jsii-calc.IPublicInterface'),
+            `${ifaceRef[api.TOKEN_REF]} starts with jsii-calc.IPublicInterface`);
+});
+
 // =================================================================================================
 
 const testNames: { [name: string]: boolean } = { };

packages/jsii-pacmak/test/expected.jsii-calc/dotnet/Amazon.JSII.Tests.CalculatorPackageId/.jsii

@@ -1098,6 +1098,31 @@
         }
       ]
     },
+    "jsii-calc.Constructors": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.Constructors",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "methods": [
+        {
+          "name": "makeClass",
+          "returns": {
+            "fqn": "jsii-calc.PublicClass"
+          },
+          "static": true
+        },
+        {
+          "name": "makeInterface",
+          "returns": {
+            "fqn": "jsii-calc.IPublicInterface"
+          },
+          "static": true
+        }
+      ],
+      "name": "Constructors"
+    },
     "jsii-calc.DefaultedConstructorArgument": {
       "assembly": "jsii-calc",
       "fqn": "jsii-calc.DefaultedConstructorArgument",
@@ -1675,6 +1700,18 @@
         }
       ]
     },
+    "jsii-calc.IPublicInterface": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.IPublicInterface",
+      "kind": "interface",
+      "methods": [
+        {
+          "abstract": true,
+          "name": "bye"
+        }
+      ],
+      "name": "IPublicInterface"
+    },
     "jsii-calc.IRandomNumberGenerator": {
       "assembly": "jsii-calc",
       "docs": {
@@ -1743,6 +1780,18 @@
         }
       ]
     },
+    "jsii-calc.InbetweenClass": {
+      "assembly": "jsii-calc",
+      "base": {
+        "fqn": "jsii-calc.PublicClass"
+      },
+      "fqn": "jsii-calc.InbetweenClass",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "name": "InbetweenClass"
+    },
     "jsii-calc.InterfaceImplementedByAbstractClass": {
       "assembly": "jsii-calc",
       "datatype": true,
@@ -2852,6 +2901,20 @@
         }
       ]
     },
+    "jsii-calc.PublicClass": {
+      "assembly": "jsii-calc",
+      "fqn": "jsii-calc.PublicClass",
+      "initializer": {
+        "initializer": true
+      },
+      "kind": "class",
+      "methods": [
+        {
+          "name": "hello"
+        }
+      ],
+      "name": "PublicClass"
+    },
     "jsii-calc.ReferenceEnumFromScopedPackage": {
       "assembly": "jsii-calc",
       "docs": {
@@ -3762,5 +3825,5 @@
     }
   },
   "version": "0.7.13",
-  "fingerprint": "mc9Rni6GLgVDz8M6CGHapEiYbWsdEIl7CmBI0Qn+KXU="
+  "fingerprint": "WNp0Sw1d2+3FaQD0Fn01K4wYQi7Ms3w+NQatOylD1kM="
 }