Use _PyDict_Pop() only when available (CPython 3.6+).

Cython/Compiler/Optimize.py

@@ -2931,8 +2931,9 @@ class OptimizeBuiltinCalls(Visitor.NodeRefCleanupMixin,
 
         return self._substitute_method_call(
             node, function,
-            "_PyDict_Pop", self.PyDict_Pop_func_type,
-            'pop', is_unbound_method, args)
+            "__Pyx_PyDict_Pop", self.PyDict_Pop_func_type,
+            'pop', is_unbound_method, args,
+            utility_code=load_c_utility('py_dict_pop'))
 
     Pyx_PyInt_BinopInt_func_type = PyrexTypes.CFuncType(
         PyrexTypes.py_object_type, [

Cython/Utility/Optimize.c

@@ -269,6 +269,26 @@ static CYTHON_INLINE PyObject *__Pyx_PyDict_SetDefault(PyObject *d, PyObject *ke
 
 #define __Pyx_PyDict_Clear(d) (PyDict_Clear(d), 0)
 
+
+/////////////// py_dict_pop.proto ///////////////
+
+#if CYTHON_COMPILING_IN_CPYTHON && PY_VERSION_HEX > 0x030600B3
+#define __Pyx_PyDict_Pop(d, key, default_value) _PyDict_Pop(d, key, default_value)
+#else
+static CYTHON_INLINE PyObject *__Pyx_PyDict_Pop(PyObject *d, PyObject *key, PyObject *default_value); /*proto*/
+#endif
+
+
+/////////////// py_dict_pop ///////////////
+
+#if !(CYTHON_COMPILING_IN_CPYTHON && PY_VERSION_HEX > 0x030600B3)
+static CYTHON_INLINE PyObject *__Pyx_PyDict_Pop(PyObject *d, PyObject *key, PyObject *default_value) {
+    // 'default_value' can be NULL
+    return PyObject_CallMethodObjArgs(d, PYIDENT("pop"), key, default_value);
+}
+#endif
+
+
 /////////////// dict_iter.proto ///////////////
 
 static CYTHON_INLINE PyObject* __Pyx_dict_iterator(PyObject* dict, int is_dict, PyObject* method_name,