bpo-45000: Raise SyntaxError when try to delete __debug__ (GH-27947) (GH-27957)

(cherry picked from commit 551da597a0996b0fb3af425f48aa5bc63ea6b963)
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 88503dc..43780ce 100644
--- a/Lib/test/test_syntax.py
+++ b/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 '='?
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-08-25-23-17-32.bpo-45000.XjmyLl.rst b/Misc/NEWS.d/next/Core and Builtins/2021-08-25-23-17-32.bpo-45000.XjmyLl.rst
new file mode 100644
index 0000000..96c95cc
--- /dev/null
+++ b/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.
diff --git a/Python/compile.c b/Python/compile.c
index a237899..d55b0be 100644
--- a/Python/compile.c
+++ b/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;
 }