give a py3k warning when 'nonlocal' is used as a variable name

Lib/test/test_py3kwarn.py

@@ -28,53 +28,35 @@ class TestPy3KWarnings(unittest.TestCase):
             exec "`2`" in {}
         self.assertWarning(None, w, expected)
 
-    def test_bool_assign(self):
+    def test_forbidden_names(self):
         # So we don't screw up our globals
         def safe_exec(expr):
             def f(**kwargs): pass
             exec expr in {'f' : f}
 
-        expected = "assignment to True or False is forbidden in 3.x"
+        tests = [("True", "assignment to True or False is forbidden in 3.x"),
+                 ("False", "assignment to True or False is forbidden in 3.x"),
+                 ("nonlocal", "nonlocal is a keyword in 3.x")]
         with check_warnings() as w:
-            safe_exec("True = False")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("False = True")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            try:
-                safe_exec("obj.False = True")
-            except NameError: pass
-            self.assertWarning(None, w, expected)
-            w.reset()
-            try:
-                safe_exec("obj.True = False")
-            except NameError: pass
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("def False(): pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("def True(): pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("class False: pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("class True: pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("def f(True=43): pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("def f(False=None): pass")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("f(False=True)")
-            self.assertWarning(None, w, expected)
-            w.reset()
-            safe_exec("f(True=1)")
-            self.assertWarning(None, w, expected)
+            for keyword, expected in tests:
+                safe_exec("{0} = False".format(keyword))
+                self.assertWarning(None, w, expected)
+                w.reset()
+                try:
+                    safe_exec("obj.{0} = True".format(keyword))
+                except NameError:
+                    pass
+                self.assertWarning(None, w, expected)
+                w.reset()
+                safe_exec("def {0}(): pass".format(keyword))
+                self.assertWarning(None, w, expected)
+                w.reset()
+                safe_exec("class {0}: pass".format(keyword))
+                self.assertWarning(None, w, expected)
+                w.reset()
+                safe_exec("def f({0}=43): pass".format(keyword))
+                self.assertWarning(None, w, expected)
+                w.reset()
 
 
     def test_type_inequality_comparisons(self):

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 2.7 alpha 1
 Core and Builtins
 -----------------
 
+- Using ``nonlocal`` as a variable name will now raise a Py3k SyntaxWarning
+  because it is a reserved work in 3.x.
+
 - On windows, os.chdir given unicode was not working if GetCurrentDirectoryW
   returned a path longer than MAX_PATH. (But It's doubtful this code path is
   really executed because I cannot move to such directory on win2k)

Python/ast.c

@@ -131,9 +131,14 @@ forbidden_check(struct compiling *c, const node *n, const char *x)
 {
     if (!strcmp(x, "None"))
         return ast_error(n, "assignment to None");
-    if (Py_Py3kWarningFlag && !(strcmp(x, "True") && strcmp(x, "False")) &&
-        !ast_warn(c, n, "assignment to True or False is forbidden in 3.x"))
-        return 0;
+    if (Py_Py3kWarningFlag) {
+        if (!(strcmp(x, "True") && strcmp(x, "False")) &&
+            !ast_warn(c, n, "assignment to True or False is forbidden in 3.x"))
+            return 0;
+        if (!strcmp(x, "nonlocal") &&
+            !ast_warn(c, n, "nonlocal is a keyword in 3.x"))
+            return 0;
+    }
     return 1;
 }