SF bug #460020: bug or feature: unicode() and subclasses.

Given an immutable type M, and an instance I of a subclass of M, the
constructor call M(I) was just returning I as-is; but it should return a
new instance of M.  This fixes it for M in {int, long}.  Strings, floats
and tuples remain to be done.
Added new macros PyInt_CheckExact and PyLong_CheckExact, to more easily
distinguish between "is" and "is a" (i.e., only an int passes
PyInt_CheckExact, while any sublass of int passes PyInt_Check).
Added private API function _PyLong_Copy.

2 files changed, 29 insertions, 3 deletions

diff --git a/Objects/abstract.c b/Objects/abstract.c
index 5361b1d..2bd0fcc 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -4,6 +4,7 @@
 #include "Python.h"
 #include <ctype.h>
 #include "structmember.h" /* we need the offsetof() macro from there */
+#include "longintrepr.h"
 
 #define NEW_STYLE_NUMBER(o) PyType_HasFeature((o)->ob_type, \
 				Py_TPFLAGS_CHECKTYPES)
@@ -818,10 +819,14 @@ PyNumber_Int(PyObject *o)
 
 	if (o == NULL)
 		return null_error();
-	if (PyInt_Check(o)) {
+	if (PyInt_CheckExact(o)) {
 		Py_INCREF(o);
 		return o;
 	}
+	if (PyInt_Check(o)) {
+		PyIntObject *io = (PyIntObject*)o;
+		return PyInt_FromLong(io->ob_ival);
+	}
 	if (PyString_Check(o))
 		return int_from_string(PyString_AS_STRING(o), 
 				       PyString_GET_SIZE(o));
@@ -868,10 +873,12 @@ PyNumber_Long(PyObject *o)
 
 	if (o == NULL)
 		return null_error();
-	if (PyLong_Check(o)) {
+	if (PyLong_CheckExact(o)) {
 		Py_INCREF(o);
 		return o;
 	}
+	if (PyLong_Check(o))
+		return _PyLong_Copy((PyLongObject *)o);
 	if (PyString_Check(o))
 		/* need to do extra error checking that PyLong_FromString() 
 		 * doesn't do.  In particular long('9.5') must raise an
diff --git a/Objects/longobject.c b/Objects/longobject.c
index c7608aa..b9271e6 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -51,6 +51,25 @@ _PyLong_New(int size)
 	return PyObject_NEW_VAR(PyLongObject, &PyLong_Type, size);
 }
 
+PyObject *
+_PyLong_Copy(PyLongObject *src)
+{
+	PyLongObject *result;
+	int i;
+
+	assert(src != NULL);
+	i = src->ob_size;
+	if (i < 0)
+		i = -(i);
+	result = _PyLong_New(i);
+	if (result != NULL) {
+		result->ob_size = i;
+		while (--i >= 0)
+			result->ob_digit[i] = src->ob_digit[i];
+	}
+	return (PyObject *)result;
+}
+
 /* Create a new long int object from a C long int */
 
 PyObject *
@@ -2205,7 +2224,7 @@ long_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
 	tmp = (PyLongObject *)long_new(&PyLong_Type, args, kwds);
 	if (tmp == NULL)
 		return NULL;
-	assert(PyLong_Check(tmp));
+	assert(PyLong_CheckExact(tmp));
 	n = tmp->ob_size;
 	if (n < 0)
 		n = -n;