Fix: 'issubclass' must check arguments.

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/type/TypeBuiltins.java

@@ -528,10 +528,36 @@ public boolean isInstance(Object cls, Object instance) {
     @GenerateNodeFactory
     static abstract class SubclassCheckNode extends PythonBinaryBuiltinNode {
         @Child private IsSubtypeNode isSubtypeNode = IsSubtypeNode.create();
+        @Child private TypeNodes.IsSameTypeNode isSameTypeNode = TypeNodes.IsSameTypeNode.create();
+
+        @Specialization(guards = {"!isNativeClass(cls)", "!isNativeClass(derived)"})
+        boolean doManagedManaged(LazyPythonClass cls, LazyPythonClass derived) {
+            return isSameType(cls, derived) || isSubtypeNode.execute(derived, cls);
+        }
 
         @Specialization
-        boolean instanceCheck(LazyPythonClass cls, Object derived) {
-            return cls == derived || isSubtypeNode.execute(derived, cls);
+        boolean doObjectObject(Object cls, Object derived,
+                        @Cached("create()") TypeNodes.IsTypeNode isClsTypeNode,
+                        @Cached("create()") TypeNodes.IsTypeNode isDerivedTypeNode) {
+            if (isSameType(cls, derived)) {
+                return true;
+            }
+
+            // no profiles required because IsTypeNode profiles already
+            if (isClsTypeNode.execute(cls) && isDerivedTypeNode.execute(derived)) {
+                return isSubtypeNode.execute(derived, cls);
+            }
+            if (!isDerivedTypeNode.execute(derived)) {
+                throw raise(PythonBuiltinClassType.TypeError, "issubclass() arg 1 must be a class");
+            }
+            if (!isClsTypeNode.execute(cls)) {
+                throw raise(PythonBuiltinClassType.TypeError, "issubclass() arg 2 must be a class or tuple of classes");
+            }
+            return false;
+        }
+
+        protected boolean isSameType(Object a, Object b) {
+            return isSameTypeNode.execute(a, b);
         }
     }
 

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/type/TypeNodes.java

@@ -686,6 +686,11 @@ boolean doBuiltinType(@SuppressWarnings("unused") PythonBuiltinClassType obj) {
         boolean doManagedClass(PythonAbstractNativeObject obj,
                         @Cached("create()") IsBuiltinClassProfile profile,
                         @Cached("create()") GetLazyClassNode getClassNode) {
+            // TODO(fa): this check may not be enough since a type object may indirectly inherit
+            // from 'type'
+            // CPython has two different checks if some object is a type:
+            // 1. test if type flag 'Py_TPFLAGS_TYPE_SUBCLASS' is set
+            // 2. test if attribute '__bases__' is a tuple
             return profile.profileClass(getClassNode.execute(obj), PythonBuiltinClassType.PythonClass);
         }