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"SystemError: bad call flags" exceptions added as part of BPO-33012 are difficult to debug #84065

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ngie-eign mannequin opened this issue Mar 7, 2020 · 5 comments
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"SystemError: bad call flags" exceptions added as part of BPO-33012 are difficult to debug #84065

ngie-eign mannequin opened this issue Mar 7, 2020 · 5 comments
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3.7 (EOL) end of life 3.8 only security fixes 3.9 only security fixes extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error

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@ngie-eign
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ngie-eign mannequin commented Mar 7, 2020

BPO 39884
Nosy @vstinner, @ngie-eign
PRs
  • bpo-39884: Add method name in "bad call flags" error #18944
  • [3.8] bpo-39884: Add method name in "bad call flags" error (GH-18944) #18956
  • [3.7] bpo-39884: Add method name in "bad call flags" error (GH-18944) #18957
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    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 = <Date 2020-03-12.12:38:29.055>
created_at = <Date 2020-03-07.04:11:33.983>
labels = ['extension-modules', '3.8', 'type-bug', '3.7', '3.9']
title = '"SystemError: bad call flags" exceptions added as part of BPO-33012 are difficult to debug'
updated_at = <Date 2020-03-12.12:38:29.051>
user = 'https://github.com/ngie-eign'

    bugs.python.org fields:

    activity = <Date 2020-03-12.12:38:29.051>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-03-12.12:38:29.055>
closer = 'vstinner'
components = ['Extension Modules']
creation = <Date 2020-03-07.04:11:33.983>
creator = 'ngie'
dependencies = []
files = []
hgrepos = []
issue_num = 39884
keywords = ['patch']
message_count = 5.0
messages = ['363575', '364000', '364012', '364013', '364014']
nosy_count = 2.0
nosy_names = ['vstinner', 'ngie']
pr_nums = ['18944', '18956', '18957']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue39884'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']
    @ngie-eign
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    ngie-eign mannequin commented Mar 7, 2020

    When a body of C extensions needs to be ported from python <3.8 to 3.8, one of the issues one might run into is improperly defined methods in a C extension, which results in SystemErrors stating:

    >> SystemError: bad call flags

    This new behavior was added as part of Issue bpo-33012.

    While the issues definitely need to be resolved in the C extensions, where to start is not completely clear. I had to put printfs in PyCFunction_NewEx and PyDescr_NewMethod to track down the issues, e.g.,

    >> printf("method name: %s\n", method->ml_name);

    While this might be misleading for duplicate method definitions, it definitely helps narrow down the offending code.

    Adding the method name to the SystemError would be a big step in the right direction in terms of making it easier to resolve these issues.

    PS I realize that this might be masked by casting PyCFunction on methods or by not using gcc 8+, but I'd argue that C extensions need to have developer issues like this be clearer to the end-reader.

    @ngie-eign ngie-eign mannequin added 3.8 only security fixes extension-modules C modules in the Modules dir type-bug An unexpected behavior, bug, or error labels Mar 7, 2020
    @vstinner
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    New changeset c7d2d69 by Victor Stinner in branch 'master':
    bpo-39884: Add method name in "bad call flags" error (GH-18944)
    c7d2d69

    @vstinner
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    New changeset 03ac090 by Victor Stinner in branch '3.8':
    bpo-39884: Add method name in "bad call flags" error (GH-18944) (GH-18956)
    03ac090

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    New changeset 6a12676 by Victor Stinner in branch '3.7':
    bpo-39884: Add method name in "bad call flags" error (GH-18944) (GH-18957)
    6a12676

    @vstinner
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    While the issues definitely need to be resolved in the C extensions, where to start is not completely clear. I had to put printfs in PyCFunction_NewEx and PyDescr_NewMethod to track down the issues, e.g., (...)

    I agree, I had the same issue :-) I fixed the issue in 3.7, 3.8 and master branches.

    In 3.7, the modified functions are different and the error message was different but similar.

    Thanks for your bug report ;-)

    @vstinner vstinner added 3.7 (EOL) end of life 3.9 only security fixes labels Mar 12, 2020
    @vstinner vstinner added 3.7 (EOL) end of life 3.9 only security fixes labels Mar 12, 2020
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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