Fix automatic conversions of function/method args for java interfaces… (

jython#296)

Handle automatic conversions of function/method args for Java interfaces when default methods are present. Prior to this change (and from Java 8 on) the presence of default methods in interfaces would prevent Jython from recognising them as a match in Java method invocation. A test is added.

ACKNOWLEDGMENTS

@@ -197,6 +197,7 @@ Jython in ways large and small, in no particular order:
     Zhihong (Ted) Yu
     Matthew Schweiss (GitHub: TheMatt2)
     Diogo Teles Sant'Anna (GitHub: diogoteles08)
+    Phil Turmel (GitHub: pturmel)
 
 
 Local Variables:

Lib/test/test_java_integration.py

@@ -42,7 +42,7 @@
 import org.python.core.Options
 
 from javatests import Issue1833
-from javatests.ProxyTests import NullToString, Person
+from javatests.ProxyTests import NullToString, Person, ConsumerCaller
 
 from clamp import SerializableProxies
 from unittest.case import skip
@@ -914,6 +914,13 @@ def __call__(self):
         self.data.append(42)
 
 
+class ConsumerMethod(object):
+    def __init__(self):
+        self.data = list()
+    def doit(self, item):
+        self.data.append(item)
+
+
 class SingleMethodInterfaceTest(unittest.TestCase):
 
     def setUp(self):
@@ -958,6 +965,20 @@ def test_some_noncallable_object(self):
             exc.exception, TypeError,
             "submit(): 1st arg can't be coerced to java.util.concurrent.Callable, java.lang.Runnable")
 
+    def test_consumer_function(self):
+        x = list()
+        def f(item):
+            x.append(item)
+        future = self.executor.submit(ConsumerCaller(f))
+        future.get()
+        self.assertEqual(x, [42])
+
+    def test_consumer_method(self):
+        obj = ConsumerMethod()
+        future = self.executor.submit(ConsumerCaller(obj.doit))
+        future.get()
+        self.assertEqual(obj.data, [42])
+
 
 def test_main():
     test_support.run_unittest(
@@ -983,5 +1004,6 @@ def test_main():
         SingleMethodInterfaceTest,
         )
 
+
 if __name__ == "__main__":
     test_main()

NEWS

@@ -20,6 +20,8 @@ New Features
 
 
 Jython 2.7.4a1 Bugs fixed
+    - [ GH-277 ] Fix automatic conversions of function/method args for java
+                 interfaces with default methods.
     - [ GH-269 ] Upgrade Google Guava to 32.0.1 (CVE-2023-2976)
     - [ GH-264 ] Create a security policy
     - [ GH-254 ] Regression in socket.socket.sendall for sending Unicode

src/org/python/core/PyFunction.java

@@ -518,6 +518,9 @@ public Object __tojava__(Class<?> c) {
                 String name = null;
                 for (Method method : c.getMethods()) {
                     if (method.getDeclaringClass() != Object.class) {
+                        if (method.isDefault()) {
+                            continue;
+                        }
                         if (name == null || name.equals(method.getName())) {
                             name = method.getName();
                         } else {
@@ -541,7 +544,7 @@ private Object proxy( Class<?> c ) {
     @Override
     public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable {
         // Handle invocation when invoked through Proxy (as coerced to single method interface)
-        if (method.getDeclaringClass() == Object.class) {
+        if (method.getDeclaringClass() == Object.class || method.isDefault()) {
             return method.invoke( this, args );
         } else if (args == null || args.length == 0) {
             return __call__().__tojava__(method.getReturnType());

src/org/python/core/PyMethod.java

@@ -382,6 +382,9 @@ public Object __tojava__(Class<?> c) {
                 String name = null;
                 for (Method method : c.getMethods()) {
                     if (method.getDeclaringClass() != Object.class) {
+                        if (method.isDefault()) {
+                            continue;
+                        }
                         if (name == null || name.equals(method.getName())) {
                             name = method.getName();
                         } else {
@@ -404,7 +407,7 @@ private Object proxy( Class<?> c ) {
 
     public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable {
         // Handle invocation when invoked through Proxy (as coerced to single method interface)
-        if (method.getDeclaringClass() == Object.class) {
+        if (method.getDeclaringClass() == Object.class || method.isDefault()) {
             return method.invoke( this, args );
         } else if (args == null || args.length == 0) {
             return __call__().__tojava__(method.getReturnType());

tests/java/javatests/ProxyTests.java

@@ -1,5 +1,7 @@
 package javatests;
 
+import java.util.function.Consumer;
+
 public class ProxyTests {
 
     public static class Person {
@@ -39,4 +41,16 @@ public static class NullToString {
         public String toString() { return null; }
     }
 
+    public static class ConsumerCaller implements Runnable {
+        protected final Consumer<Object> target;
+
+        public ConsumerCaller(Consumer<Object> target) {
+            this.target = target;
+        }
+
+        @Override
+        public void run() {
+            target.accept(42);
+        }
+    }
 }