Issue #26182: Raise DeprecationWarning for improper use of async/await keywords

1 files changed, 20 insertions, 0 deletions

diff --git a/Python/ast.c b/Python/ast.c
index 765d24e11b..deea579c0d 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -938,6 +938,26 @@ forbidden_name(struct compiling *c, identifier name, const node *n,
         ast_error(c, n, "assignment to keyword");
         return 1;
     }
+    if (PyUnicode_CompareWithASCIIString(name, "async") == 0 ||
+        PyUnicode_CompareWithASCIIString(name, "await") == 0)
+    {
+        PyObject *message = PyUnicode_FromString(
+            "'async' and 'await' will become reserved keywords"
+            " in Python 3.7");
+        if (message == NULL) {
+            return 1;
+        }
+        if (PyErr_WarnExplicitObject(
+                PyExc_DeprecationWarning,
+                message,
+                c->c_filename,
+                LINENO(n),
+                NULL,
+                NULL) < 0)
+        {
+            return 1;
+        }
+    }
     if (full_checks) {
         const char * const *p;
         for (p = FORBIDDEN; *p; p++) {