Fixed a compile error when calling default methods from another module due to the delegate methods being marked synthetic

Fixes #56

Author: luontola

README.md

@@ -208,6 +208,11 @@ optimizations to that mechanism may break Retrolambda.
 Version History
 ---------------
 
+### Upcoming
+
+- Fixed a compile error when calling default methods from another module
+  ([Issue #56](https://github.com/orfjackal/retrolambda/issues/56))
+
 ### Retrolambda 2.0.3 (2015-06-07)
 
 - Fixed Retrolambda generating stack map frames for Java 5 bytecode,

end-to-end-tests/src/main/java/net/orfjackal/retrolambda/test/InMainSources.java

@@ -1,4 +1,4 @@
-// Copyright © 2013-2014 Esko Luontola <www.orfjackal.net>
+// Copyright © 2013-2015 Esko Luontola <www.orfjackal.net>
 // This software is released under the Apache License 2.0.
 // The license text is at http://www.apache.org/licenses/LICENSE-2.0
 
@@ -19,4 +19,20 @@ public static int callLambda() throws Exception {
     public static List<String> useLambdaOfImportedType(List<String> items) {
         return Lists.transform(items, String::toUpperCase);
     }
+
+    public interface Interface {
+        default String defaultMethod() {
+            return "default";
+        }
+    }
+
+    public static class Implementer implements Interface {
+    }
+
+    public static class Overrider implements Interface {
+        @Override
+        public String defaultMethod() {
+            return "overridden";
+        }
+    }
 }

end-to-end-tests/src/test/java/net/orfjackal/retrolambda/test/DefaultMethodsTest.java

@@ -472,6 +472,8 @@ default Callable<String> captureThis() {
      */
     @Test
     public void default_methods_with_lambdas_in_another_package() throws Exception {
+        assumeThat(SystemUtils.JAVA_VERSION_FLOAT, is(lessThan(1.8f)));
+
         UsesLambdasInAnotherPackage obj = new UsesLambdasInAnotherPackage() {
         };
         assertThat(obj.stateless().call(), is("foo"));
@@ -480,6 +482,34 @@ public void default_methods_with_lambdas_in_another_package() throws Exception {
                 obj.getClass().getDeclaredMethods(), arrayWithSize(2));
     }
 
+    /**
+     * Though we use {@link InMainSources}, because the Retrolambda Maven plugin
+     * processes the main sources separately from the test sources, the effect is
+     * the same as if they were in another module.
+     */
+    @Test
+    public void calling_default_methods_from_another_module_through_interface() {
+        InMainSources.Interface implementer = new InMainSources.Implementer();
+        assertThat(implementer.defaultMethod(), is("default"));
+
+        InMainSources.Interface overrider = new InMainSources.Overrider();
+        assertThat(overrider.defaultMethod(), is("overridden"));
+    }
+
+    /**
+     * Fixes issue of the generated delegate methods being marked as synthetic,
+     * in which case the Java compiler causes "error: cannot find symbol"
+     * for direct calls to those methods.
+     */
+    @Test
+    public void calling_default_methods_from_another_module_through_class() {
+        InMainSources.Implementer implementer = new InMainSources.Implementer();
+        assertThat(implementer.defaultMethod(), is("default"));
+
+        InMainSources.Overrider overrider = new InMainSources.Overrider();
+        assertThat(overrider.defaultMethod(), is("overridden"));
+    }
+
 
     /**
      * We're unable to backport default methods if we cannot modify the interface,
@@ -553,7 +583,7 @@ default void annotatedDefaultMethod() {
         }
 
         @SomeAnnotation(4)
-        public static void annotatedStaticMethod() {
+        static void annotatedStaticMethod() {
         }
     }
 

retrolambda/src/main/java/net/orfjackal/retrolambda/interfaces/AddMethodDefaultImplementations.java

@@ -29,7 +29,7 @@ public void visit(int version, int access, String name, String signature, String
     public void visitEnd() {
         for (MethodInfo method : analyzer.getDefaultMethods(Type.getObjectType(className))) {
             Bytecode.generateDelegateMethod(cv,
-                    ACC_PUBLIC | ACC_SYNTHETIC,
+                    ACC_PUBLIC,
                     method.toMethodRef().toHandle(),
                     method.getDefaultMethodImpl().toHandle());
         }