Support for lambdas with marker interfaces

Fixes #62

Author: luontola

README.md

@@ -208,6 +208,11 @@ optimizations to that mechanism may break Retrolambda.
 Version History
 ---------------
 
+### Upcoming
+
+- Support for lambdas with marker interfaces
+  ([Issue #62](https://github.com/orfjackal/retrolambda/issues/62))
+
 ### Retrolambda 2.0.4 (2015-07-08)
 
 - Fixed a compile error when calling default methods from another module

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

@@ -99,6 +99,16 @@ public interface LambdaConstant {
         Callable<String> LAMBDA = () -> "foo";
     }
 
+    @Test
+    public void lambdas_with_marker_interfaces_due_to_intersection_types() throws Exception {
+        // We must use something other than java.io.Serializable as the marker interface,
+        // because serializable lambdas are signified by a flag to LambdaMetafactory.altMetafactory
+        Callable<String> lambda = (Callable<String> & Cloneable) () -> "foo";
+
+        assertThat(lambda, is(instanceOf(Cloneable.class)));
+        assertThat(lambda.call(), is("foo"));
+    }
+
     @Test
     public void method_references_to_virtual_methods() throws Exception {
         String foo = "foo";

retrolambda/src/main/java/net/orfjackal/retrolambda/lambdas/Types.java

@@ -14,7 +14,14 @@ public class Types {
 
     public static Object asmToJdkType(Object arg, ClassLoader classLoader, MethodHandles.Lookup caller) throws Exception {
         if (arg instanceof Type) {
-            return toMethodType((Type) arg, classLoader);
+            Type type = (Type) arg;
+            if (type.getSort() == Type.METHOD) {
+                return toMethodType(type, classLoader);
+            } else if (type.getSort() == Type.OBJECT) {
+                return toClass(type, classLoader);
+            } else {
+                throw new IllegalArgumentException("Unsupported type: " + type);
+            }
         } else if (arg instanceof Handle) {
             return toMethodHandle((Handle) arg, classLoader, caller);
         } else {
@@ -26,6 +33,10 @@ public static MethodType toMethodType(Type type, ClassLoader classLoader) {
         return MethodType.fromMethodDescriptorString(type.getInternalName(), classLoader);
     }
 
+    private static Class<?> toClass(Type type, ClassLoader classLoader) throws ClassNotFoundException {
+        return classLoader.loadClass(type.getInternalName().replace('/', '.'));
+    }
+
     public static MethodHandle toMethodHandle(Handle handle, ClassLoader classLoader, MethodHandles.Lookup lookup) throws Exception {
         MethodType type = MethodType.fromMethodDescriptorString(handle.getDesc(), classLoader);
         Class<?> owner = classLoader.loadClass(handle.getOwner().replace('/', '.'));

retrolambda/src/test/java/net/orfjackal/retrolambda/lambdas/TypesTest.java

@@ -0,0 +1,54 @@
+// 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
+
+package net.orfjackal.retrolambda.lambdas;
+
+import org.junit.Test;
+import org.objectweb.asm.*;
+
+import java.lang.invoke.*;
+import java.util.function.Predicate;
+
+import static net.orfjackal.retrolambda.lambdas.Types.asmToJdkType;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+@SuppressWarnings("UnnecessaryLocalVariable")
+public class TypesTest {
+
+    private ClassLoader classLoader = getClass().getClassLoader();
+    private MethodHandles.Lookup lookup = MethodHandles.lookup();
+
+    @Test
+    public void asmToJdkType_MethodType() throws Exception {
+        Type input = Type.getMethodType("(I)Ljava/util/function/Predicate;");
+        MethodType output = MethodType.methodType(Predicate.class, int.class);
+
+        assertThat(asmToJdkType(input, classLoader, lookup), is(output));
+    }
+
+    @Test
+    public void asmToJdkType_MethodHandle() throws Exception {
+        Handle input = new Handle(Opcodes.H_INVOKESTATIC, "java/lang/String", "valueOf", "(I)Ljava/lang/String;");
+        MethodHandle output = lookup.findStatic(String.class, "valueOf", MethodType.methodType(String.class, int.class));
+
+        assertThat(asmToJdkType(input, classLoader, lookup).toString(), is(output.toString()));
+    }
+
+    @Test
+    public void asmToJdkType_Class() throws Exception {
+        Type input = Type.getType(String.class);
+        Class<?> output = String.class;
+
+        assertThat(asmToJdkType(input, classLoader, lookup), is(equalTo(output)));
+    }
+
+    @Test
+    public void asmToJdkType_everything_else() throws Exception {
+        String input = "foo";
+        String output = input;
+
+        assertThat(asmToJdkType(input, classLoader, lookup), is(output));
+    }
+}