Add warnings for assignment or deletion of variables and attributes

named 'None'.  Still to do: function definition parameter lists, and
function call keyword arguments.

diff --git a/Python/compile.c b/Python/compile.c
index e448dd2eb8bf901e4f31be68ff23d401080d40f6..41d31d212c457e787e56e530e99bdeeba3de1895 100644 (file)
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -574,6 +574,7 @@ block_pop(struct compiling *c, int type)
 
 /* Prototype forward declarations */
 
+static int issue_warning(char *, char *, int);
 static int com_init(struct compiling *, char *);
 static void com_free(struct compiling *);
 static void com_push(struct compiling *, int);
@@ -988,6 +989,23 @@ com_lookup_arg(PyObject *dict, PyObject *name)
                return PyInt_AS_LONG(v);
 }
 
+static int
+none_assignment_check(struct compiling *c, char *name, int assigning)
+{
+       if (name[0] == 'N' && strcmp(name, "None") == 0) {
+               char *msg;
+               if (assigning)
+                       msg = "assigment to None";
+               else
+                       msg = "deleting None";
+               if (issue_warning(msg, c->c_filename, c->c_lineno) < 0) {
+                       c->c_errors++;
+                       return -1;
+               }
+       }
+       return 0;
+}
+
 static void
 com_addop_varname(struct compiling *c, int kind, char *name)
 {
@@ -997,6 +1015,13 @@ com_addop_varname(struct compiling *c, int kind, char *name)
        int op = STOP_CODE;
        char buffer[MANGLE_LEN];
 
+       if (kind != VAR_LOAD &&
+           none_assignment_check(c, name, kind == VAR_STORE))
+       {
+               c->c_errors++;
+               i = 255;
+               goto done;
+       }
        if (_Py_Mangle(c->c_private, name, buffer, sizeof(buffer)))
                name = buffer;
        if (name == NULL || (v = PyString_InternFromString(name)) == NULL) {
@@ -2489,6 +2514,8 @@ com_augassign_attr(struct compiling *c, node *n, int opcode, node *augn)
 static void
 com_assign_attr(struct compiling *c, node *n, int assigning)
 {
+       if (none_assignment_check(c, STR(n), assigning))
+               return;
        com_addopname(c, assigning ? STORE_ATTR : DELETE_ATTR, n);
        com_pop(c, assigning ? 2 : 1);
 }