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gh-130164: Fix inspect.Signature.bind() handling of positional-only args without defaults #130192

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Merged
merged 2 commits into from
Feb 18, 2025
Merged

gh-130164: Fix inspect.Signature.bind() handling of positional-only args without defaults #130192

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gh-130164: Fix inspect.signature.bind() handling of positional-only a…
jacobtylerwalls Feb 16, 2025
4a0b38a
Fix typo
jacobtylerwalls Feb 16, 2025
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3 changes: 3 additions & 0 deletions Lib/inspect.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3077,6 +3077,9 @@ def _bind(self, args, kwargs, *, partial=False):
break
elif param.name in kwargs:
if param.kind == _POSITIONAL_ONLY:
if param.default is _empty:
msg = f'missing a required positional-only argument: {param.name!r}'
raise TypeError(msg)
# Raise a TypeError once we are sure there is no
# **kwargs param later.
pos_only_param_in_kwargs.append(param)
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8 changes: 6 additions & 2 deletions Lib/test/test_inspect/test_inspect.py
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Expand Up @@ -5149,7 +5149,11 @@ class TestSignatureBind(unittest.TestCase):
def call(func, *args, **kwargs):
sig = inspect.signature(func)
ba = sig.bind(*args, **kwargs)
return func(*ba.args, **ba.kwargs)
# Prevent unexpected success of assertRaises(TypeError, ...)
try:
return func(*ba.args, **ba.kwargs)
except TypeError as e:
raise AssertionError from e

def test_signature_bind_empty(self):
def test():
Expand Down Expand Up @@ -5349,7 +5353,7 @@ def test(a_po, b_po, c_po=3, /, foo=42, *, bar=50, **kwargs):
self.assertEqual(self.call(test, 1, 2, c_po=4),
(1, 2, 3, 42, 50, {'c_po': 4}))

with self.assertRaisesRegex(TypeError, "missing 2 required positional arguments"):
with self.assertRaisesRegex(TypeError, "missing a required positional-only argument: 'a_po'"):
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@jacobtylerwalls jacobtylerwalls Feb 16, 2025 •
edited
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Some of these cases could be moved to the existing method test_signature_bind_posonly_kwargs() if desired?

self.call(test, a_po=1, b_po=2)

def without_var_kwargs(c_po=3, d_po=4, /):
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2025-02-16-08-56-48.gh-issue-130164.vvoaU2.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fixed failure to raise :exc:`TypeError` in :meth:`inspect.Signature.bind`
for positional-only arguments provided by keyword when a variadic keyword
argument (e.g. ``**kwargs``) is present.
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