From abb9a448dee3e18c69080231fbeba980bf048211 Mon Sep 17 00:00:00 2001 From: Brandt Bucher Date: Sat, 1 Feb 2020 03:08:34 -0800 Subject: Update sum comment. (#18240) --- Python/bltinmodule.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'Python/bltinmodule.c') diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c index 4f833c1f462..5818eb9e38f 100644 --- a/Python/bltinmodule.c +++ b/Python/bltinmodule.c @@ -2440,7 +2440,11 @@ builtin_sum_impl(PyObject *module, PyObject *iterable, PyObject *start) empty = [] sum([[x] for x in range(10)], empty) - would change the value of empty. */ + would change the value of empty. In fact, using + in-place addition rather that binary addition for + any of the steps introduces subtle behavior changes: + + https://bugs.python.org/issue18305 */ temp = PyNumber_Add(result, item); Py_DECREF(result); Py_DECREF(item); -- cgit v1.2.3