commit 9dbb09fc27b99d2c08b8f56db71018eb828cc7cd
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Mon Mar 25 00:47:55 2019 -0700
committer Raymond Hettinger <rhettinger@users.noreply.github.com> Mon Mar 25 00:47:55 2019 -0700
tree f94682f665dc72fdca95b91ed43bc693a4a776e4
parent 0e05d8a82dedf6f020b71a780507fb45ad5fd00f

bpo-36218: Fix handling of heterogeneous values in list.sort (GH-12209) GH-12532)

(cherry picked from commit dd5417afcf8924bcdd7077351941ad21727ef644)

Co-authored-by: Rémi Lapeyre <remi.lapeyre@henki.fr>

Objects/listobject.c

diff --git a/Objects/listobject.c b/Objects/listobject.c
index 7dc68a7..d795f66 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2250,19 +2250,28 @@
 
             if (key->ob_type != key_type) {
                 keys_are_all_same_type = 0;
-                break;
+                /* If keys are in tuple we must loop over the whole list to make
+                   sure all items are tuples */
+                if (!keys_are_in_tuples) {
+                    break;
+                }
             }
 
-            if (key_type == &PyLong_Type) {
-                if (ints_are_bounded && Py_ABS(Py_SIZE(key)) > 1)
+            if (keys_are_all_same_type) {
+                if (key_type == &PyLong_Type &&
+                    ints_are_bounded &&
+                    Py_ABS(Py_SIZE(key)) > 1) {
+
                     ints_are_bounded = 0;
+                }
+                else if (key_type == &PyUnicode_Type &&
+                         strings_are_latin &&
+                         PyUnicode_KIND(key) != PyUnicode_1BYTE_KIND) {
+
+                        strings_are_latin = 0;
+                    }
+                }
             }
-            else if (key_type == &PyUnicode_Type){
-                if (strings_are_latin &&
-                    PyUnicode_KIND(key) != PyUnicode_1BYTE_KIND)
-                strings_are_latin = 0;
-            }
-        }
 
         /* Choose the best compare, given what we now know about the keys. */
         if (keys_are_all_same_type) {
@@ -2290,10 +2299,12 @@
         if (keys_are_in_tuples) {
             /* Make sure we're not dealing with tuples of tuples
              * (remember: here, key_type refers list [key[0] for key in keys]) */
-            if (key_type == &PyTuple_Type)
+            if (key_type == &PyTuple_Type) {
                 ms.tuple_elem_compare = safe_object_compare;
-            else
+            }
+            else {
                 ms.tuple_elem_compare = ms.key_compare;
+            }
 
             ms.key_compare = unsafe_tuple_compare;
         }