commit 036fe85bd3e6cd01093d836d71792a1966f961e8
author HongWeipeng <961365124@qq.com> Tue Nov 26 15:54:49 2019 +0800
committer Inada Naoki <songofacandy@gmail.com> Tue Nov 26 16:54:49 2019 +0900
tree cc1147b732a9913d34134641b321b15ddff47707
parent 386d00cc341b549800776b906bfc6b20ea40c7db

bpo-27145: small_ints[x] could be returned in long_add and long_sub (GH-15716)

Objects/longobject.c

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 294308e..f056797 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -3206,7 +3206,7 @@
     if (sign < 0) {
         Py_SIZE(z) = -Py_SIZE(z);
     }
-    return long_normalize(z);
+    return maybe_small_long(long_normalize(z));
 }
 
 static PyObject *
@@ -3254,13 +3254,15 @@
         return PyLong_FromLong(MEDIUM_VALUE(a) - MEDIUM_VALUE(b));
     }
     if (Py_SIZE(a) < 0) {
-        if (Py_SIZE(b) < 0)
-            z = x_sub(a, b);
-        else
+        if (Py_SIZE(b) < 0) {
+            z = x_sub(b, a);
+        }
+        else {
             z = x_add(a, b);
-        if (z != NULL) {
-            assert(Py_SIZE(z) == 0 || Py_REFCNT(z) == 1);
-            Py_SIZE(z) = -(Py_SIZE(z));
+            if (z != NULL) {
+                assert(Py_SIZE(z) == 0 || Py_REFCNT(z) == 1);
+                Py_SIZE(z) = -(Py_SIZE(z));
+            }
         }
     }
     else {