bpo-40958: Avoid 'possible loss of data' warning on Windows (GH-20970)



diff --git a/Parser/pegen.c b/Parser/pegen.c
index b374740..594754c 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -397,7 +397,7 @@
     }
 
     if (p->start_rule == Py_file_input) {
-        error_line = PyErr_ProgramTextObject(p->tok->filename, lineno);
+        error_line = PyErr_ProgramTextObject(p->tok->filename, (int) lineno);
     }
 
     if (!error_line) {