diff options
| -rw-r--r-- | Lib/test/test_ast.py | 3 | ||||
| -rw-r--r-- | Misc/NEWS | 3 | ||||
| -rw-r--r-- | Python/ast.c | 16 |
3 files changed, 17 insertions, 5 deletions
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py index 4e311e4473..6dca5d2e65 100644 --- a/Lib/test/test_ast.py +++ b/Lib/test/test_ast.py @@ -150,7 +150,8 @@ class AST_Tests(unittest.TestCase): slc = ast.parse("x[::]").body[0].value.slice self.assertIsNone(slc.upper) self.assertIsNone(slc.lower) - self.assertIsNone(slc.step) + self.assertTrue(isinstance(slc.step, ast.Name)) + self.assertEqual(slc.step.id, "None") def test_from_import(self): im = ast.parse("from . import y").body[0] @@ -44,9 +44,6 @@ Core and Builtins - Assignment to None using import statements now raises a SyntaxError. -- In the slice AST type, the step field will always be None if a step expression - is not specified. - - Issue #4547: When debugging a very large function, it was not always possible to update the lineno attribute of the current frame. diff --git a/Python/ast.c b/Python/ast.c index 6ccd02fc70..0644da8300 100644 --- a/Python/ast.c +++ b/Python/ast.c @@ -1471,7 +1471,21 @@ ast_for_slice(struct compiling *c, const node *n) ch = CHILD(n, NCH(n) - 1); if (TYPE(ch) == sliceop) { - if (NCH(ch) != 1) { + if (NCH(ch) == 1) { + /* + This is an extended slice (ie "x[::]") with no expression in the + step field. We set this literally to "None" in order to + disambiguate it from x[:]. (The interpreter might have to call + __getslice__ for x[:], but it must call __getitem__ for x[::].) + */ + identifier none = new_identifier("None", c->c_arena); + if (!none) + return NULL; + ch = CHILD(ch, 0); + step = Name(none, Load, LINENO(ch), ch->n_col_offset, c->c_arena); + if (!step) + return NULL; + } else { ch = CHILD(ch, 1); if (TYPE(ch) == test) { step = ast_for_expr(c, ch); |