Fix bug #8112: don't special case Comparable and Comparator methods a…

…nymore.

Before this fix, Comparable.compareTo(Object) and
Comparator.compare(Object,Object) are specially removed and hence only
generic-bound compare() remained in Mono.Android.dll. This resulted in a
side effect that is bug #8112 - when generic information was unavailable,
it still removed Object-based compareTo() and compare(), which were the only
one implementation and resulted in missing method error.

This fix changes the way to lookup methods to save in API XML; only
"really-declared" methods remain. For generic methods JRE automatically
adds overloads for those methods with Object. We now skip them (which
gives consistent output with AOSP XML).

JavaClass.java

@@ -432,6 +432,17 @@ else if (tc instanceof TypeVariable<?>)
 	}
 
 	String getSignature (Method method)
+	{
+		StringBuffer sig = new StringBuffer ();
+		sig.append (method.getName ());
+		for (Class t : method.getParameterTypes ()) {
+			sig.append (":");
+			sig.append (t.getName ());
+		}
+		return sig.toString ();
+	}
+
+	String getGenericSignature (Method method)
 	{
 		StringBuffer sig = new StringBuffer ();
 		sig.append (method.getName ());
@@ -461,6 +472,20 @@ public void appendToDocument (Document doc, Element parent)
 		}
 	}
 
+	Comparator clscmp = new Comparator<Class> () {
+		public int compare (Class c1, Class c2) {
+			return c1.getName ().compareTo (c2.getName ());
+		}
+	};
+
+	boolean isInPublicInheritanceChain (Class cls)
+	{
+		for (Class c = cls; c != null; c = c.getSuperclass ())
+			if ((c.getModifiers () & Modifier.PUBLIC) == 0)
+				return false;
+		return true;
+	}
+
 	void doAppendToDocument (Document doc, Element parent)
 	{
 		int mods = jclass.getModifiers ();
@@ -519,6 +544,13 @@ else if (iface instanceof ParameterizedType) {
 		Class base_class = jclass.getSuperclass ();
 		Map<String, Method> methods = new HashMap <String, Method> ();
 		for (Method method : jclass.getDeclaredMethods ()) {
+			// Skip "synthetic" methods that is automatically supplied by JRE.
+			// But there is an exception scenario: if the class is derived from non-public class,
+			// don't do that - it results in excessive removal.
+			// e.g. in libcore/luni, StringBuilder inherits non-public AbstractStringBuilder.
+			if (method.isSynthetic () && isInPublicInheritanceChain (jclass))
+				continue;
+
 			int mmods = method.getModifiers ();
 
 /*
@@ -569,22 +601,8 @@ else if (iface instanceof ParameterizedType) {
 					}
 				}
 			}
-
-			Comparator clscmp = new Comparator<Class> () {
-				public int compare (Class c1, Class c2) {
-					return c1.getName ().compareTo (c2.getName ());
-				}
-			};
-
-			// These special rules are required to filter out incorrectly returned compareTo(Object) Comparable<T> implementation (maybe it is due to "erased generics").
-			if (Arrays.binarySearch (jclass.getInterfaces (), Comparable.class, clscmp) >= 0 && method.getName ().equals ("compareTo") && ptypes [0].equals (Object.class)
-			    // IF this worked in Java ... <code>if (... && ptypes [0] != jclass.GetGenericArguments () [0])</code>
-			    && !jclass.equals (java.io.ObjectStreamField.class))
-				continue;
-			if (Arrays.binarySearch (jclass.getInterfaces (), Comparator.class, clscmp) >= 0 && method.getName ().equals ("compare") && ptypes.length == 2 && ptypes [0].equals (Object.class) && ptypes [1].equals (Object.class))
-				continue;
 
-			String key = getSignature (method);
+			String key = getGenericSignature (method);
 			if (methods.containsKey (key)) {
 				Type method_type = method.getGenericReturnType ();
 				Method hashed = methods.get (key);

README

@@ -308,15 +308,3 @@ Now we use ASM to solve the issues below:
 
   android.view.MotionEvent.getSource() is also missing.
 </maybe-historical>
-
-** Erased generic issues
-
-<workarounded>
-- extraneous "CompareTo(Object)" method
-  - e.g. android.net.Uri, java.util.Calendar, java.util.Date, java.util.UUID, java.nio.Charset and so on.
-  - They implement Comparable<T> and since either <T> went away in
-    android.jar or jar2xml ignores generic type arguments and treats T
-    arg as Object, this extra method is returned.
-- similarly, Comparator<T> brings extra Compare(Object, Object) overloads.
-
-</workarounded>