[3.10] bpo-45000: Raise SyntaxError when try to delete __debug__ (GH-27947)

Lib/test/test_syntax.py

@@ -59,6 +59,10 @@
 Traceback (most recent call last):
 SyntaxError: cannot assign to __debug__
 
+>>> del __debug__
+Traceback (most recent call last):
+SyntaxError: cannot delete __debug__
+
 >>> f() = 1
 Traceback (most recent call last):
 SyntaxError: cannot assign to function call here. Maybe you meant '==' instead of '='?

Misc/NEWS.d/next/Core and Builtins/2021-08-25-23-17-32.bpo-45000.XjmyLl.rst

@@ -0,0 +1,2 @@
+A :exc:`SyntaxError` is now raised when trying to delete :const:`__debug__`.
+Patch by Dong-hee Na.

Python/compile.c

@@ -2264,6 +2264,10 @@ forbidden_name(struct compiler *c, identifier name, expr_context_ty ctx)
         compiler_error(c, "cannot assign to __debug__");
         return 1;
     }
+    if (ctx == Del && _PyUnicode_EqualToASCIIString(name, "__debug__")) {
+        compiler_error(c, "cannot delete __debug__");
+        return 1;
+    }
     return 0;
 }