https://github.com/python/typed_ast/commit/123286721923ae8f3885dbfbad94d6ca940d5c96
https://bugs.gentoo.org/874900

From 123286721923ae8f3885dbfbad94d6ca940d5c96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miro=20Hron=C4=8Dok?= <miro@hroncok.cz>
Date: Wed, 10 Nov 2021 19:15:50 +0100
Subject: [PATCH] Define _PyUnicode_DecodeUnicodeEscape even on Python 3.6+
 (#171)

--- a/ast3/Python/ast.c
+++ b/ast3/Python/ast.c
@@ -56,6 +56,8 @@ _PyBytes_DecodeEscape(const char *s,
     return PyBytes_DecodeEscape(s, len, errors, unicode, recode_encoding);
 }
 
+#endif
+
 PyObject *
 _PyUnicode_DecodeUnicodeEscape(const char *s,
                                Py_ssize_t size,
@@ -66,8 +68,6 @@ _PyUnicode_DecodeUnicodeEscape(const char *s,
     return PyUnicode_DecodeUnicodeEscape(s, size, errors);
 }
 
-#endif
-
 static int validate_stmts(asdl_seq *);
 static int validate_exprs(asdl_seq *, expr_context_ty, int);
 static int validate_nonempty_seq(asdl_seq *, const char *, const char *);