commit e62a694fee53ba7fc16d6afbaa53b373c878f300
author Raymond Hettinger <python@rcn.com> Thu Sep 08 15:25:19 2016 -0700
committer Raymond Hettinger <python@rcn.com> Thu Sep 08 15:25:19 2016 -0700
tree 08464fc231f3efbe4328ab147ea9313df73cbfc5
parent cb20a2174053148ba22d4d50a86bcef430c1b66f

Issue #26020: Fix evaluation order for set literals

Python/ceval.c

diff --git a/Python/ceval.c b/Python/ceval.c
index 0b747d8..2af78ff 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2477,14 +2477,16 @@
 
         TARGET(BUILD_SET)
         {
+            int i;
             x = PySet_New(NULL);
             if (x != NULL) {
-                for (; --oparg >= 0;) {
-                    w = POP();
+                for (i = oparg; i > 0; i--) {
+                    w = PEEK(i);
                     if (err == 0)
                         err = PySet_Add(x, w);
                     Py_DECREF(w);
                 }
+                STACKADJ(-oparg);
                 if (err != 0) {
                     Py_DECREF(x);
                     break;