Issue #26020: Fix evaluation order for set literals
diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
index 1a49edf..7594303 100644
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -388,6 +388,21 @@
t = {1,2,3}
self.assertEqual(s, t)
+ def test_set_literal_insertion_order(self):
+ # SF Issue #26020 -- Expect left to right insertion
+ s = {1, 1.0, True}
+ self.assertEqual(len(s), 1)
+ stored_value = s.pop()
+ self.assertEqual(type(stored_value), int)
+
+ def test_set_literal_evaluation_order(self):
+ # Expect left to right expression evaluation
+ events = []
+ def record(obj):
+ events.append(obj)
+ s = {record(1), record(2), record(3)}
+ self.assertEqual(events, [1, 2, 3])
+
def test_hash(self):
self.assertRaises(TypeError, hash, self.s)
diff --git a/Misc/NEWS b/Misc/NEWS
index 9125caf..1922432 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -20,6 +20,8 @@
after use of 'def' in _PyState_AddModule().
Initial patch by Christian Heimes.
+- Issue #26020: set literal evaluation order did not match documented behaviour.
+
- Issue #27782: Multi-phase extension module import now correctly allows the
``m_methods`` field to be used to add module level functions to instances
of non-module types returned from ``Py_create_mod``. Patch by Xiang Zhang.
diff --git a/Python/ceval.c b/Python/ceval.c
index 8e396fd..451791c 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2580,14 +2580,16 @@
TARGET(BUILD_SET) {
PyObject *set = PySet_New(NULL);
int err = 0;
+ int i;
if (set == NULL)
goto error;
- while (--oparg >= 0) {
- PyObject *item = POP();
+ for (i = oparg; i > 0; i--) {
+ PyObject *item = PEEK(i);
if (err == 0)
err = PySet_Add(set, item);
Py_DECREF(item);
}
+ STACKADJ(-oparg);
if (err != 0) {
Py_DECREF(set);
goto error;