From 79311cbfe718f17c89bab67d7f89da3931bfa2ac Mon Sep 17 00:00:00 2001 From: Shantanu <12621235+hauntsaninja@users.noreply.github.com> Date: Tue, 20 Dec 2022 21:29:02 -0600 Subject: [PATCH] gh-85267: Improvements to inspect.signature __text_signature__ handling (#98796) This makes a couple related changes to inspect.signature's behaviour when parsing a signature from `__text_signature__`. First, `inspect.signature` is documented as only raising ValueError or TypeError. However, in some cases, we could raise RuntimeError. This PR changes that, thereby fixing #83685. (Note that the new ValueErrors in RewriteSymbolics are caught and then reraised with a message) Second, `inspect.signature` could randomly drop parameters that it didn't understand (corresponding to `return None` in the `p` function). This is the core issue in #85267. I think this is very surprising behaviour and it seems better to fail outright. Third, adding this new failure broke a couple tests. To fix them (and to e.g. allow `inspect.signature(select.epoll.register)` as in #85267), I add constant folding of a couple binary operations to RewriteSymbolics. (There's some discussion of making signature expression evaluation arbitrary powerful in #68155. I think that's out of scope. The additional constant folding here is pretty straightforward, useful, and not much of a slippery slope) Fourth, while #85267 is incorrect about the cause of the issue, it turns out if you had consecutive newlines in __text_signature__, you'd get `tokenize.TokenError`. Finally, the `if name is invalid:` code path was dead, since `parse_name` never returned `invalid`. --- Lib/inspect.py | 25 +++++++++++++++---- Lib/test/test_inspect.py | 21 +++++++++++++++- ...2-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst | 6 +++++ 3 files changed, 46 insertions(+), 6 deletions(-) create mode 100644 Misc/NEWS.d/next/Library/2022-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst diff --git a/Lib/inspect.py b/Lib/inspect.py index 052f0bfe64b607..3db7745e8a5eeb 100644 --- a/Lib/inspect.py +++ b/Lib/inspect.py @@ -2122,7 +2122,7 @@ def _signature_strip_non_python_syntax(signature): self_parameter = None last_positional_only = None - lines = [l.encode('ascii') for l in signature.split('\n')] + lines = [l.encode('ascii') for l in signature.split('\n') if l] generator = iter(lines).__next__ token_stream = tokenize.tokenize(generator) @@ -2221,11 +2221,11 @@ def wrap_value(s): try: value = eval(s, sys_module_dict) except NameError: - raise RuntimeError() + raise ValueError if isinstance(value, (str, int, float, bytes, bool, type(None))): return ast.Constant(value) - raise RuntimeError() + raise ValueError class RewriteSymbolics(ast.NodeTransformer): def visit_Attribute(self, node): @@ -2235,7 +2235,7 @@ def visit_Attribute(self, node): a.append(n.attr) n = n.value if not isinstance(n, ast.Name): - raise RuntimeError() + raise ValueError a.append(n.id) value = ".".join(reversed(a)) return wrap_value(value) @@ -2245,6 +2245,21 @@ def visit_Name(self, node): raise ValueError() return wrap_value(node.id) + def visit_BinOp(self, node): + # Support constant folding of a couple simple binary operations + # commonly used to define default values in text signatures + left = self.visit(node.left) + right = self.visit(node.right) + if not isinstance(left, ast.Constant) or not isinstance(right, ast.Constant): + raise ValueError + if isinstance(node.op, ast.Add): + return ast.Constant(left.value + right.value) + elif isinstance(node.op, ast.Sub): + return ast.Constant(left.value - right.value) + elif isinstance(node.op, ast.BitOr): + return ast.Constant(left.value | right.value) + raise ValueError + def p(name_node, default_node, default=empty): name = parse_name(name_node) if default_node and default_node is not _empty: @@ -2252,7 +2267,7 @@ def p(name_node, default_node, default=empty): default_node = RewriteSymbolics().visit(default_node) default = ast.literal_eval(default_node) except ValueError: - return None + raise ValueError("{!r} builtin has invalid signature".format(obj)) from None parameters.append(Parameter(name, kind, default=default, annotation=empty)) # non-keyword-only parameters diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py index 78e6e9e34e5019..1b589c8df2a224 100644 --- a/Lib/test/test_inspect.py +++ b/Lib/test/test_inspect.py @@ -2525,7 +2525,7 @@ def p(name): return signature.parameters[name].default self.assertEqual(p('f'), False) self.assertEqual(p('local'), 3) self.assertEqual(p('sys'), sys.maxsize) - self.assertNotIn('exp', signature.parameters) + self.assertEqual(p('exp'), sys.maxsize - 1) test_callable(object) @@ -4323,10 +4323,29 @@ def func(*args, **kwargs): sig = inspect.signature(func) self.assertIsNotNone(sig) self.assertEqual(str(sig), '(self, /, a, b=1, *args, c, d=2, **kwargs)') + func.__text_signature__ = '($self, a, b=1, /, *args, c, d=2, **kwargs)' sig = inspect.signature(func) self.assertEqual(str(sig), '(self, a, b=1, /, *args, c, d=2, **kwargs)') + func.__text_signature__ = '(self, a=1+2, b=4-3, c=1 | 3 | 16)' + sig = inspect.signature(func) + self.assertEqual(str(sig), '(self, a=3, b=1, c=19)') + + func.__text_signature__ = '(self, a=1,\nb=2,\n\n\n c=3)' + sig = inspect.signature(func) + self.assertEqual(str(sig), '(self, a=1, b=2, c=3)') + + func.__text_signature__ = '(self, x=does_not_exist)' + with self.assertRaises(ValueError): + inspect.signature(func) + func.__text_signature__ = '(self, x=sys, y=inspect)' + with self.assertRaises(ValueError): + inspect.signature(func) + func.__text_signature__ = '(self, 123)' + with self.assertRaises(ValueError): + inspect.signature(func) + def test_base_class_have_text_signature(self): # see issue 43118 from test.ann_module7 import BufferedReader diff --git a/Misc/NEWS.d/next/Library/2022-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst b/Misc/NEWS.d/next/Library/2022-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst new file mode 100644 index 00000000000000..e69fd1ca1c2f3b --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst @@ -0,0 +1,6 @@ +Several improvements to :func:`inspect.signature`'s handling of ``__text_signature``. +- Fixes a case where :func:`inspect.signature` dropped parameters +- Fixes a case where :func:`inspect.signature` raised :exc:`tokenize.TokenError` +- Allows :func:`inspect.signature` to understand defaults involving binary operations of constants +- :func:`inspect.signature` is documented as only raising :exc:`TypeError` or :exc:`ValueError`, but sometimes raised :exc:`RuntimeError`. These cases now raise :exc:`ValueError` +- Removed a dead code path