complain about "global __class__" in a class body (closes #17983)

1 files changed, 6 insertions, 0 deletions

diff --git a/Python/symtable.c b/Python/symtable.c
index 55898f99bf..e686d9ebc3 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -1236,6 +1236,12 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
         asdl_seq *seq = s->v.Global.names;
         for (i = 0; i < asdl_seq_LEN(seq); i++) {
             identifier name = (identifier)asdl_seq_GET(seq, i);
+            if (st->st_cur->ste_type == ClassBlock &&
+                !PyUnicode_CompareWithASCIIString(name, "__class__")) {
+                PyErr_SetString(PyExc_SyntaxError, "cannot make __class__ global");
+                PyErr_SyntaxLocationEx(st->st_filename, s->lineno, s->col_offset);
+                return 0;
+            }
             long cur = symtable_lookup(st, name);
             if (cur < 0)
                 VISIT_QUIT(st, 0);