Fix issue with Constructor proxies.

Bug: 28659889
Change-Id: I4307916c79e7b56608c3ff5c9bbe83e175254f28
(cherry picked from commit 52c9da0925c67265bf353f5a66b7cb5541a88046)
diff --git a/runtime/native/java_lang_reflect_Constructor.cc b/runtime/native/java_lang_reflect_Constructor.cc
index ddcaade..1e93b1c 100644
--- a/runtime/native/java_lang_reflect_Constructor.cc
+++ b/runtime/native/java_lang_reflect_Constructor.cc
@@ -47,7 +47,8 @@
 
 static jobjectArray Constructor_getExceptionTypes(JNIEnv* env, jobject javaMethod) {
   ScopedFastNativeObjectAccess soa(env);
-  ArtMethod* method = ArtMethod::FromReflectedMethod(soa, javaMethod);
+  ArtMethod* method = ArtMethod::FromReflectedMethod(soa, javaMethod)
+      ->GetInterfaceMethodIfProxy(sizeof(void*));
   mirror::ObjectArray<mirror::Class>* result_array =
       method->GetDexFile()->GetExceptionTypesForMethod(method);
   if (result_array == nullptr) {
diff --git a/test/044-proxy/expected.txt b/test/044-proxy/expected.txt
index be7023e..2a5f0b9 100644
--- a/test/044-proxy/expected.txt
+++ b/test/044-proxy/expected.txt
@@ -95,3 +95,5 @@
 5.8
 JNI_OnLoad called
 callback
+Found constructor.
+Found constructors with 0 exceptions
diff --git a/test/044-proxy/src/ConstructorProxy.java b/test/044-proxy/src/ConstructorProxy.java
new file mode 100644
index 0000000..95d150c
--- /dev/null
+++ b/test/044-proxy/src/ConstructorProxy.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+
+/**
+ * Tests proxies when used with constructor methods.
+ */
+class ConstructorProxy implements InvocationHandler {
+  public static void main() {
+    try {
+      new ConstructorProxy().runTest();
+    } catch (Exception e) {
+      System.out.println("Unexpected failure occured");
+      e.printStackTrace();
+    }
+  }
+
+  public void runTest() throws Exception {
+    Class<?> proxyClass = Proxy.getProxyClass(
+            getClass().getClassLoader(),
+            new Class<?>[] { Runnable.class }
+    );
+    Constructor<?> constructor = proxyClass.getConstructor(InvocationHandler.class);
+    System.out.println("Found constructor.");
+    // We used to crash when asking the exception types of the constructor, because the runtime was
+    // not using the non-proxy ArtMethod
+    Object[] exceptions = constructor.getExceptionTypes();
+    System.out.println("Found constructors with " + exceptions.length + " exceptions");
+  }
+
+  @Override
+  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+    return args[0];
+  }
+}
+
diff --git a/test/044-proxy/src/Main.java b/test/044-proxy/src/Main.java
index 1f23b95..9dadb7c 100644
--- a/test/044-proxy/src/Main.java
+++ b/test/044-proxy/src/Main.java
@@ -31,6 +31,7 @@
         NarrowingTest.main(null);
         FloatSelect.main(null);
         NativeProxy.main(args);
+        ConstructorProxy.main();
     }
 
     // The following code maps from the actual proxy class names (eg $Proxy2) to their test output