BUG: numpy.einsum indexing arrays now accept numpy int type

See numpy#15961.

Author: rlintott

numpy/core/src/multiarray/multiarraymodule.c

@@ -2437,7 +2437,6 @@ einsum_list_to_subscripts(PyObject *obj, char *subscripts, int subsize)
     }
     size = PySequence_Size(obj);
 
-
     for (i = 0; i < size; ++i) {
         item = PySequence_Fast_GET_ITEM(obj, i);
         /* Ellipsis */
@@ -2459,46 +2458,48 @@ einsum_list_to_subscripts(PyObject *obj, char *subscripts, int subsize)
             subscripts[subindex++] = '.';
             ellipsis = 1;
         }
-        /* Subscript */
-        else if (PyInt_Check(item) || PyLong_Check(item)) {
-            long s = PyInt_AsLong(item);
-            npy_bool bad_input = 0;
+        else {
+            long s = PyLong_AsLong(item);
+            /* Subscript */
+            if(!PyErr_Occurred()) {
+                npy_bool bad_input = 0;
 
-            if (subindex + 1 >= subsize) {
-                PyErr_SetString(PyExc_ValueError,
-                        "subscripts list is too long");
-                Py_DECREF(obj);
-                return -1;
-            }
+                if (subindex + 1 >= subsize) {
+                    PyErr_SetString(PyExc_ValueError,
+                            "subscripts list is too long");
+                    Py_DECREF(obj);
+                    return -1;
+                }
 
-            if ( s < 0 ) {
-                bad_input = 1;
-            }
-            else if (s < 26) {
-                subscripts[subindex++] = 'A' + (char)s;
-            }
-            else if (s < 2*26) {
-                subscripts[subindex++] = 'a' + (char)s - 26;
+                if ( s < 0 ) {
+                    bad_input = 1;
+                }
+                else if (s < 26) {
+                    subscripts[subindex++] = 'A' + (char)s;
+                }
+                else if (s < 2*26) {
+                    subscripts[subindex++] = 'a' + (char)s - 26;
+                }
+                else {
+                    bad_input = 1;
+                }
+
+                if (bad_input) {
+                    PyErr_SetString(PyExc_ValueError,
+                            "subscript is not within the valid range [0, 52)");
+                    Py_DECREF(obj);
+                    return -1;
+                }
             }
+            /* Invalid */
             else {
-                bad_input = 1;
-            }
-
-            if (bad_input) {
                 PyErr_SetString(PyExc_ValueError,
-                        "subscript is not within the valid range [0, 52)");
+                        "each subscript must be either an integer "
+                        "or an ellipsis");
                 Py_DECREF(obj);
                 return -1;
             }
-        }
-        /* Invalid */
-        else {
-            PyErr_SetString(PyExc_ValueError,
-                    "each subscript must be either an integer "
-                    "or an ellipsis");
-            Py_DECREF(obj);
-            return -1;
-        }
+        }        
     }
 
     Py_DECREF(obj);