[Python-checkins] gh-85267: Improvements to inspect.signature __text_signature__ handling (#98796)
JelleZijlstra
webhook-mailer at python.org
Tue Dec 20 22:29:08 EST 2022
https://github.com/python/cpython/commit/79311cbfe718f17c89bab67d7f89da3931bfa2ac
commit: 79311cbfe718f17c89bab67d7f89da3931bfa2ac
branch: main
author: Shantanu <12621235+hauntsaninja at users.noreply.github.com>
committer: JelleZijlstra <jelle.zijlstra at gmail.com>
date: 2022-12-20T19:29:02-08:00
summary:
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`.
files:
A Misc/NEWS.d/next/Library/2022-10-28-07-24-34.gh-issue-85267.xUy_Wm.rst
M Lib/inspect.py
M Lib/test/test_inspect.py
diff --git a/Lib/inspect.py b/Lib/inspect.py
index 052f0bfe64b6..3db7745e8a5e 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 78e6e9e34e50..1b589c8df2a2 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 000000000000..e69fd1ca1c2f
--- /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
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