[Python-checkins] cpython (2.7): Issue #11576: Fixed timedelta subtraction glitch on big timedelta values

Wed Apr 6 04:14:27 CEST 2011

http://hg.python.org/cpython/rev/202a9feb1fd6
changeset: 69165:202a9feb1fd6
branch: 2.7
parent: 69162:5616cbce0bee
user: Alexander Belopolsky <alexander.belopolsky at gmail.com>
date: Tue Apr 05 22:12:22 2011 -0400
summary:
 Issue #11576: Fixed timedelta subtraction glitch on big timedelta values
files:
 Lib/test/test_datetime.py | 7 +++++++
 Modules/datetimemodule.c | 15 ++++++++-------
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -231,6 +231,13 @@
 eq(a//10, td(0, 7*24*360))
 eq(a//3600000, td(0, 0, 7*24*1000))
 
+ # Issue #11576
+ eq(td(999999999, 86399, 999999) - td(999999999, 86399, 999998),
+ td(0, 0, 1))
+ eq(td(999999999, 1, 1) - td(999999999, 1, 0),
+ td(0, 0, 1))
+
+
 def test_disallowed_computations(self):
 a = timedelta(42)
 
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -1737,13 +1737,14 @@
 
 if (PyDelta_Check(left) && PyDelta_Check(right)) {
 /* delta - delta */
- PyObject *minus_right = PyNumber_Negative(right);
- if (minus_right) {
- result = delta_add(left, minus_right);
- Py_DECREF(minus_right);
- }
- else
- result = NULL;
+ /* The C-level additions can't overflow because of the
+ * invariant bounds.
+ */
+ int days = GET_TD_DAYS(left) - GET_TD_DAYS(right);
+ int seconds = GET_TD_SECONDS(left) - GET_TD_SECONDS(right);
+ int microseconds = GET_TD_MICROSECONDS(left) -
+ GET_TD_MICROSECONDS(right);
+ result = new_delta(days, seconds, microseconds, 1);
 }
 
 if (result == Py_NotImplemented)
-- 
Repository URL: http://hg.python.org/cpython
