bpo-36346: Raise DeprecationWarning in deprecated usages.

Raise DeprecationWarning when: * PyArg_ParseTuple with 'u', 'Z' format. * PyUnicode_FromStringAndSize(NULL, size) We can not use C level deprecation because these API will be not removed.
python · methane · Feb 22, 2021 · Jun 17, 2020 · Jun 17, 2020 · Feb 22, 2021
commit 8352afa9a5ce7cf40fe3500f205b42a8ee003ba2
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-02-22-19-00-00.bpo-36346.uAoni0.rst b/Misc/NEWS.d/next/Core and Builtins/2021-02-22-19-00-00.bpo-36346.uAoni0.rst
@@ -0,0 +1,2 @@
+``PyArg_Parse*()`` functions now emits ``DeprecationWarning`` when ``u`` or
+``Z`` format is used.
diff --git a/Python/getargs.c b/Python/getargs.c
@@ -1014,7 +1014,10 @@ convertsimple(PyObject *arg, const char **p_format, va_list *p_va, int flags,
     case 'u': /* raw unicode buffer (Py_UNICODE *) */
     case 'Z': /* raw unicode buffer or None */
     {
-        // TODO: Raise DeprecationWarning
+        if (PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                "getargs: The '%c' format is deprecated. Use 'U' instead.", c)) {
+            return NULL;
+        }
 _Py_COMP_DIAG_PUSH
 _Py_COMP_DIAG_IGNORE_DEPR_DECLS
         Py_UNICODE **p = va_arg(*p_va, Py_UNICODE **);
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		``PyArg_Parse*()`` functions now emits ``DeprecationWarning`` when ``u`` or
		``Z`` format is used.