Stop producing or using OverflowWarning. PEP 237 thought this would

happen in 2.3, but nobody noticed it still was getting generated (the
warning was disabled by default).  OverflowWarning and
PyExc_OverflowWarning should be removed for 2.5, and left notes all over
saying so.

Doc/lib/libexcs.tex

@@ -460,7 +460,7 @@ The class hierarchy for built-in exceptions is:
 	  +-- DeprecationWarning
 	  +-- PendingDeprecationWarning
 	  +-- SyntaxWarning
-	  +-- OverflowWarning
+	  +-- OverflowWarning (not generated in 2.4; won't exist in 2.5)
 	  +-- RuntimeWarning
 	  +-- FutureWarning
 \end{verbatim}

Include/pyerrors.h

@@ -74,6 +74,7 @@ PyAPI_DATA(PyObject *) PyExc_UserWarning;
 PyAPI_DATA(PyObject *) PyExc_DeprecationWarning;
 PyAPI_DATA(PyObject *) PyExc_PendingDeprecationWarning;
 PyAPI_DATA(PyObject *) PyExc_SyntaxWarning;
+/* PyExc_OverflowWarning will go away for Python 2.5 */
 PyAPI_DATA(PyObject *) PyExc_OverflowWarning;
 PyAPI_DATA(PyObject *) PyExc_RuntimeWarning;
 PyAPI_DATA(PyObject *) PyExc_FutureWarning;

Lib/test/test_exceptions.py

@@ -85,15 +85,16 @@ except NameError: pass
 
 r(OverflowError)
 # XXX
-# Obscure:  this test relies on int+int raising OverflowError if the
-# ints are big enough.  But ints no longer do that by default.  This
-# test will have to go away someday.  For now, we can convert the
-# transitional OverflowWarning into an error.
+# Obscure:  in 2.2 and 2.3, this test relied on changing OverflowWarning
+# into an error, in order to trigger OverflowError.  In 2.4, OverflowWarning
+# should no longer be generated, so the focus of the test shifts to showing
+# that OverflowError *isn't* generated.  OverflowWarning should be gone
+# in Python 2.5, and then the filterwarnings() call, and this comment,
+# should go away.
 warnings.filterwarnings("error", "", OverflowWarning, __name__)
 x = 1
-try:
-    while 1: x = x+x
-except OverflowError: pass
+for dummy in range(128):
+    x += x  # this simply shouldn't blow up
 
 r(RuntimeError)
 print '(not used any more?)'

Lib/test/test_warnings.py

@@ -44,6 +44,7 @@ class TestModule(unittest.TestCase):
 
     def test_warn_specific_category(self):
         text = 'None'
+        # XXX OverflowWarning should go away for Python 2.5.
         for category in [DeprecationWarning, FutureWarning, OverflowWarning,
                     PendingDeprecationWarning, RuntimeWarning,
                     SyntaxWarning, UserWarning, Warning]:

Lib/warnings.py

@@ -250,5 +250,6 @@ def _getcategory(category):
 
 # Module initialization
 _processoptions(sys.warnoptions)
+# XXX OverflowWarning should go away for Python 2.5.
 simplefilter("ignore", category=OverflowWarning, append=1)
 simplefilter("ignore", category=PendingDeprecationWarning, append=1)

Misc/NEWS

@@ -12,6 +12,12 @@ What's New in Python 2.4 alpha 3?
 Core and builtins
 -----------------
 
+- OverflowWarning is no longer generated.  PEP 237 scheduled this to
+  occur in Python 2.3, but since OverflowWarning was disabled by default,
+  nobody realized it was still being generated.  On the chance that user
+  code is still using them, the Python builtin OverflowWarning, and
+  corresponding C API PyExc_OverflowWarning, will exist until Python 2.5.
+
 - Py_InitializeEx has been added.
 
 - Fix the order of application of decorators.  The proper order is bottom-up;

Objects/intobject.c

@@ -10,19 +10,6 @@ PyInt_GetMax(void)
 	return LONG_MAX;	/* To initialize sys.maxint */
 }
 
-/* Return 1 if exception raised, 0 if caller should retry using longs */
-static int
-err_ovf(char *msg)
-{
-	if (PyErr_Warn(PyExc_OverflowWarning, msg) < 0) {
-		if (PyErr_ExceptionMatches(PyExc_OverflowWarning))
-			PyErr_SetString(PyExc_OverflowError, msg);
-		return 1;
-	}
-	else
-		return 0;
-}
-
 /* Integers are quite normal objects, to make object handling uniform.
    (Using odd pointers to represent integers would save much space
    but require extra checks for this special case throughout the code.)
@@ -306,11 +293,8 @@ PyInt_FromString(char *s, char **pend, int base)
 		PyErr_SetString(PyExc_ValueError, buffer);
 		return NULL;
 	}
-	else if (errno != 0) {
-		if (err_ovf("string/unicode conversion"))
-			return NULL;
+	else if (errno != 0)
 		return PyLong_FromString(s, pend, base);
-	}
 	if (pend)
 		*pend = end;
 	return PyInt_FromLong(x);
@@ -396,8 +380,6 @@ int_add(PyIntObject *v, PyIntObject *w)
 	x = a + b;
 	if ((x^a) >= 0 || (x^b) >= 0)
 		return PyInt_FromLong(x);
-	if (err_ovf("integer addition"))
-		return NULL;
 	return PyLong_Type.tp_as_number->nb_add((PyObject *)v, (PyObject *)w);
 }
 
@@ -410,8 +392,6 @@ int_sub(PyIntObject *v, PyIntObject *w)
 	x = a - b;
 	if ((x^a) >= 0 || (x^~b) >= 0)
 		return PyInt_FromLong(x);
-	if (err_ovf("integer subtraction"))
-		return NULL;
 	return PyLong_Type.tp_as_number->nb_subtract((PyObject *)v,
 						     (PyObject *)w);
 }
@@ -475,8 +455,6 @@ int_mul(PyObject *v, PyObject *w)
 		   32 * absdiff <= absprod -- 5 good bits is "close enough" */
 		if (32.0 * absdiff <= absprod)
 			return PyInt_FromLong(longprod);
-		else if (err_ovf("integer multiplication"))
-			return NULL;
 		else
 			return PyLong_Type.tp_as_number->nb_multiply(v, w);
 	}
@@ -501,11 +479,8 @@ i_divmod(register long x, register long y,
 		return DIVMOD_ERROR;
 	}
 	/* (-sys.maxint-1)/-1 is the only overflow case. */
-	if (y == -1 && x < 0 && x == -x) {
-		if (err_ovf("integer division"))
-			return DIVMOD_ERROR;
+	if (y == -1 && x < 0 && x == -x)
 		return DIVMOD_OVERFLOW;
-	}
 	xdivy = x / y;
 	xmody = x - xdivy * y;
 	/* If the signs of x and y differ, and the remainder is non-0,
@@ -654,8 +629,6 @@ int_pow(PyIntObject *v, PyIntObject *w, PyIntObject *z)
 			if (temp == 0)
 				break; /* Avoid ix / 0 */
 			if (ix / temp != prev) {
-				if (err_ovf("integer exponentiation"))
-					return NULL;
 				return PyLong_Type.tp_as_number->nb_power(
 					(PyObject *)v,
 					(PyObject *)w,
@@ -666,9 +639,7 @@ int_pow(PyIntObject *v, PyIntObject *w, PyIntObject *z)
 	        if (iw==0) break;
 	 	prev = temp;
 	 	temp *= temp;	/* Square the value of temp */
-	 	if (prev!=0 && temp/prev!=prev) {
-			if (err_ovf("integer exponentiation"))
-				return NULL;
+	 	if (prev != 0 && temp / prev != prev) {
 			return PyLong_Type.tp_as_number->nb_power(
 				(PyObject *)v, (PyObject *)w, (PyObject *)z);
 		}
@@ -701,10 +672,7 @@ int_neg(PyIntObject *v)
 	a = v->ob_ival;
 	x = -a;
 	if (a < 0 && x < 0) {
-		PyObject *o;
-		if (err_ovf("integer negation"))
-			return NULL;
-		o = PyLong_FromLong(a);
+		PyObject *o = PyLong_FromLong(a);
 		if (o != NULL) {
 			PyObject *result = PyNumber_Negative(o);
 			Py_DECREF(o);

Python/exceptions.c

@@ -1560,7 +1560,7 @@ PyDoc_STRVAR(SyntaxWarning__doc__,
 "Base class for warnings about dubious syntax.");
 
 PyDoc_STRVAR(OverflowWarning__doc__,
-"Base class for warnings about numeric overflow.");
+"Base class for warnings about numeric overflow.  Won't exist in Python 2.5.");
 
 PyDoc_STRVAR(RuntimeWarning__doc__,
 "Base class for warnings about dubious runtime behavior.");
@@ -1635,6 +1635,7 @@ PyObject *PyExc_UserWarning;
 PyObject *PyExc_DeprecationWarning;
 PyObject *PyExc_PendingDeprecationWarning;
 PyObject *PyExc_SyntaxWarning;
+/* PyExc_OverflowWarning should be removed for Python 2.5 */
 PyObject *PyExc_OverflowWarning;
 PyObject *PyExc_RuntimeWarning;
 PyObject *PyExc_FutureWarning;
@@ -1726,6 +1727,7 @@ static struct {
  {"PendingDeprecationWarning", &PyExc_PendingDeprecationWarning, &PyExc_Warning,
   PendingDeprecationWarning__doc__},
  {"SyntaxWarning", &PyExc_SyntaxWarning, &PyExc_Warning, SyntaxWarning__doc__},
+ /* OverflowWarning should be removed for Python 2.5 */
  {"OverflowWarning", &PyExc_OverflowWarning, &PyExc_Warning,
   OverflowWarning__doc__},
  {"RuntimeWarning", &PyExc_RuntimeWarning, &PyExc_Warning,