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inspect.signature() raises RuntimeError on failed to resolve the default argument value #87284

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tk0miya mannequin opened this issue Feb 3, 2021 · 7 comments
Closed

inspect.signature() raises RuntimeError on failed to resolve the default argument value #87284

tk0miya mannequin opened this issue Feb 3, 2021 · 7 comments
Labels
3.9 only security fixes 3.10 only security fixes 3.11 only security fixes stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@tk0miya
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tk0miya mannequin commented Feb 3, 2021

BPO 43118
Nosy @gvanrossum, @hongweipeng, @miss-islington, @tk0miya
PRs
  • bpo-43118: in inspect.signature,use 'base' to help parse 'base.__text_signature__' #30285
  • [3.10] bpo-43118: Fix bug in inspect.signature around 'base.__text_signature__' (GH-30285) #30765
  • [3.9] bpo-43118: Fix bug in inspect.signature around 'base.__text_signature__' (GH-30285) #30766
    		•
    Files
  • inspect.patch
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = None
created_at = <Date 2021-02-03.15:04:12.206>
labels = ['type-bug', 'library', '3.9', '3.10', '3.11']
title = 'inspect.signature() raises RuntimeError on failed to resolve the default argument value'
updated_at = <Date 2022-01-22.17:28:57.262>
user = 'https://github.com/tk0miya'

    bugs.python.org fields:

    activity = <Date 2022-01-22.17:28:57.262>
actor = 'gvanrossum'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-02-03.15:04:12.206>
creator = 'tkomiya'
dependencies = []
files = ['49788']
hgrepos = []
issue_num = 43118
keywords = ['patch']
message_count = 5.0
messages = ['386212', '386213', '411188', '411196', '411268']
nosy_count = 4.0
nosy_names = ['gvanrossum', 'hongweipeng', 'miss-islington', 'tkomiya']
pr_nums = ['30285', '30765', '30766']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue43118'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']
    @tk0miya
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    tk0miya mannequin commented Feb 3, 2021

    inspect.signature() raises RuntimeError on failed to resolve the default argument value. For example, it fails to inspect a subclass of io.BufferedReader:

    Example:

    import inspect
import io


class MyBufferedReader(io.BufferedReader):
    """buffer reader class."""


inspect.signature(MyBufferedReader)

    Result:

    Traceback (most recent call last):
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2042, in wrap_value
    value = eval(s, module_dict)
  File "<string>", line 1, in <module>
NameError: name 'DEFAULT_BUFFER_SIZE' is not defined

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2045, in wrap_value
    value = eval(s, sys_module_dict)
  File "<string>", line 1, in <module>
NameError: name 'DEFAULT_BUFFER_SIZE' is not defined

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/tkomiya/work/tmp/doc/example.py", line 9, in <module>
    inspect.signature(MyBufferedReader)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 3130, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2879, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2397, in _signature_from_callable
    return _signature_fromstr(sigcls, obj, text_sig)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2095, in _signature_fromstr
    p(name, default)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2077, in p
    default_node = RewriteSymbolics().visit(default_node)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/ast.py", line 407, in visit
    return visitor(node)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2069, in visit_Name
    return wrap_value(node.id)
  File "/Users/tkomiya/.pyenv/versions/3.9.1/lib/python3.9/inspect.py", line 2047, in wrap_value
    raise RuntimeError()
RuntimeError

    In my investigation, inspect.signature() tries to evaluate the default argument value of the class constructor. But it fails to evaluate because of the 2nd argument of the constructor takes a constant; DEFAULT_BUFFER_SIZE, but it is not found on the current context.

    I think it would be better to search the constants for the modules of the base classes. I just made a simple patch to resolve this bug.

    @tk0miya tk0miya mannequin added 3.7 (EOL) end of life 3.8 only security fixes 3.10 only security fixes 3.9 only security fixes stdlib Python modules in the Lib dir labels Feb 3, 2021
    @tk0miya
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    tk0miya mannequin commented Feb 3, 2021

    FWIW, I succeeded to inspect the class with importing the constant from the base module as a workaround:

    import inspect
import io

from io import DEFAULT_BUFFER_SIZE


class MyBufferedReader(io.BufferedReader):
    """buffer reader class."""


inspect.signature(MyBufferedReader)

    @iritkatriel iritkatriel added 3.11 only security fixes type-bug An unexpected behavior, bug, or error and removed 3.7 (EOL) end of life 3.8 only security fixes labels Jan 18, 2022
    @gvanrossum
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    New changeset 881a763 by Weipeng Hong in branch 'main':
    bpo-43118: Fix bug in inspect.signature around 'base.__text_signature__' (GH-30285)
    881a763

    @miss-islington
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    New changeset 9e3ff82 by Miss Islington (bot) in branch '3.9':
    bpo-43118: Fix bug in inspect.signature around 'base.__text_signature__' (GH-30285)
    9e3ff82

    @gvanrossum
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    New changeset 83aef4d by Miss Islington (bot) in branch '3.10':
    bpo-43118: Fix bug in inspect.signature around 'base.__text_signature__' (GH-30285) (bpo-30765)
    83aef4d

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @zhuofeng6
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    any question about this issue? if not, i think it is better to close it

    @gvanrossum
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    Looks like this was fixed in 3.9, the repro doesn't raise there.

    @picnixz picnixz mentioned this issue Aug 9, 2023
    Closed
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