diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py index 86934666449..b921f4a5d68 100644 --- a/Lib/test/test_ast.py +++ b/Lib/test/test_ast.py @@ -635,6 +635,13 @@ class AST_Tests(unittest.TestCase): with self.assertRaises(SyntaxError): ast.parse('f"{x=}"', feature_version=(3, 7)) + def test_constant_as_name(self): + for constant in "True", "False", "None": + expr = ast.Expression(ast.Name(constant, ast.Load())) + ast.fix_missing_locations(expr) + with self.assertRaisesRegex(ValueError, f"Name node can't be used with '{constant}' constant"): + compile(expr, "", "eval") + class ASTHelpers_Test(unittest.TestCase): maxDiff = None diff --git a/Misc/NEWS.d/next/Core and Builtins/2020-06-05-12-48-28.bpo-40870.9cd2sk.rst b/Misc/NEWS.d/next/Core and Builtins/2020-06-05-12-48-28.bpo-40870.9cd2sk.rst new file mode 100644 index 00000000000..8e943a29f33 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2020-06-05-12-48-28.bpo-40870.9cd2sk.rst @@ -0,0 +1,2 @@ +Raise :exc:`ValueError` when validating custom AST's where the constants +``True``, ``False`` and ``None`` are used within a :class:`ast.Name` node. diff --git a/Python/ast.c b/Python/ast.c index 594879bd0ef..0a999fcca43 100644 --- a/Python/ast.c +++ b/Python/ast.c @@ -21,6 +21,25 @@ static int validate_nonempty_seq(asdl_seq *, const char *, const char *); static int validate_stmt(stmt_ty); static int validate_expr(expr_ty, expr_context_ty); +static int +validate_name(PyObject *name) +{ + assert(PyUnicode_Check(name)); + static const char * const forbidden[] = { + "None", + "True", + "False", + NULL + }; + for (int i = 0; forbidden[i] != NULL; i++) { + if (_PyUnicode_EqualToASCIIString(name, forbidden[i])) { + PyErr_Format(PyExc_ValueError, "Name node can't be used with '%s' constant", forbidden[i]); + return 0; + } + } + return 1; +} + static int validate_comprehension(asdl_seq *gens) { @@ -199,6 +218,9 @@ validate_expr(expr_ty exp, expr_context_ty ctx) actual_ctx = exp->v.Starred.ctx; break; case Name_kind: + if (!validate_name(exp->v.Name.id)) { + return 0; + } actual_ctx = exp->v.Name.ctx; break; case List_kind: