add explicit cast to avoid GCC warnings with -Wwrite-strings

diff --git a/Cython/Compiler/Nodes.py b/Cython/Compiler/Nodes.py
index f127e56dd2fb20fb0496eecadcca724c1326e1d8..10700cd2ed1cfb8b7fb807cfcfffcedab41e507e 100644 (file)
--- a/Cython/Compiler/Nodes.py
+++ b/Cython/Compiler/Nodes.py
@@ -5118,8 +5118,8 @@ impl = r"""
 static int __Pyx_GetVtable(PyObject *dict, void *vtabptr) {
     int result;
     PyObject *pycobj;
-    
-    pycobj = PyMapping_GetItemString(dict, "__pyx_vtable__");
+
+    pycobj = PyMapping_GetItemString(dict, (char *)"__pyx_vtable__");
     if (!pycobj)
         goto bad;
     *(void **)vtabptr = PyCObject_AsVoidPtr(pycobj);