Implement dict copy C helper function

Author: vsakkas

mypyc/lib-rt/CPy.h

@@ -347,6 +347,7 @@ PyObject *CPyDict_ItemsView(PyObject *dict);
 PyObject *CPyDict_Keys(PyObject *dict);
 PyObject *CPyDict_Values(PyObject *dict);
 PyObject *CPyDict_Items(PyObject *dict);
+PyObject *CPyDict_Copy(PyObject *dict);
 PyObject *CPyDict_GetKeysIter(PyObject *dict);
 PyObject *CPyDict_GetItemsIter(PyObject *dict);
 PyObject *CPyDict_GetValuesIter(PyObject *dict);

mypyc/lib-rt/dict_ops.c

@@ -226,6 +226,13 @@ PyObject *CPyDict_Items(PyObject *dict) {
     return list;
 }
 
+PyObject *CPyDict_Copy(PyObject *dict) {
+    if (PyDict_CheckExact(dict)) {
+        return PyDict_Copy(dict);
+    }
+    return PyObject_CallMethod(dict, "copy", NULL);
+}
+
 PyObject *CPyDict_GetKeysIter(PyObject *dict) {
     if (PyDict_CheckExact(dict)) {
         // Return dict itself to indicate we can use fast path instead.

mypyc/primitives/dict_ops.py

@@ -147,9 +147,8 @@
     name='copy',
     arg_types=[dict_rprimitive],
     return_type=dict_rprimitive,
-    c_function_name='PyDict_Copy',
-    error_kind=ERR_MAGIC,
-)
+    c_function_name='CPyDict_Copy',
+    error_kind=ERR_MAGIC)
 
 # list(dict.keys())
 dict_keys_op = custom_op(

mypyc/test-data/irbuild-dict.test

@@ -321,5 +321,5 @@ def f(d: Dict[int, int]) -> Dict[int, int]:
 def f(d):
     d, r0 :: dict
 L0:
-    r0 = PyDict_Copy(d)
+    r0 = CPyDict_Copy(d)
     return r0