AttributeError: module 'email.errors' has no attribute 'InvalidHeaderError'.

[The-Compiler]

Bug report

email._header_value_parser tries to raise errors.InvalidHeaderError, but that does not exist (and as far as I can tell, never did):

>>> from email.headerregistry import HeaderRegistry
>>> reg = HeaderRegistry()
>>> reg('Content-Disposition', 'attachment; 0*00="foo"')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.10/email/headerregistry.py", line 604, in __call__
    return self[name](name, value)
  File "/usr/lib/python3.10/email/headerregistry.py", line 192, in __new__
    cls.parse(value, kwds)
  File "/usr/lib/python3.10/email/headerregistry.py", line 448, in parse
    kwds['parse_tree'] = parse_tree = cls.value_parser(value)
  File "/usr/lib/python3.10/email/_header_value_parser.py", line 2705, in parse_content_disposition_header
    disp_header.append(parse_mime_parameters(value[1:]))
  File "/usr/lib/python3.10/email/_header_value_parser.py", line 2569, in parse_mime_parameters
    token, value = get_parameter(value)
  File "/usr/lib/python3.10/email/_header_value_parser.py", line 2431, in get_parameter
    token, value = get_section(value)
  File "/usr/lib/python3.10/email/_header_value_parser.py", line 2382, in get_section
    section.defects.append(errors.InvalidHeaderError(
AttributeError: module 'email.errors' has no attribute 'InvalidHeaderError'. Did you mean: 'InvalidHeaderDefect'?

Code:

cpython/Lib/email/_header_value_parser.py

Lines 2381 to 2383 in d853758

	if digits[0] == '0' and digits != '0':
	section.defects.append(errors.InvalidHeaderError(
	"section number has an invalid leading 0"))

This was added in 97f43c0 by @bitdancer pretty much some 10 years ago, and I don't think it ever worked (but nor could I find anyone running into this so far): The git history doesn't know anything about an email.errors.InvalidHeaderError.

Found via Hypothesis while testing my own parsing code - cc @Zac-HD if you want to see another instance of "the curse of hypothesis" 😉

Your environment

• CPython versions tested on: 3.7.13, 3.8.13, 3.9.13, 3.10.4, 3.11.0b1
• Operating system and architecture: Archlinux, x86_64

[warsaw]

Oh wow, nice find.

[Zac-HD]

Nice find!

On a meta-level though this suggests that CPython could really benefit from adopting some static analysis tooling and/or coverage requirements which are table stakes for any critical project... maybe I can argue for that instead of PBT at the next summit 😅

[The-Compiler]

On a meta-level though this suggests that CPython could really benefit from adopting some static analysis tooling and/or coverage requirements which are table stakes for any critical project... maybe I can argue for that instead of PBT at the next summit

Agreed! FWIW I tried to run flake8 with a lot of ignored errors and manual processing, and I believe I now have another handful of bugs/PRs to report... 😅

Lib/_pyio.py:2165:28: F821 undefined name 'locale'
Lib/enum.py:1643:28: F821 undefined name 'cls_name'
Lib/test/test_shutil.py:1597:78: F821 undefined name 'x'
Lib/test/test_shutil.py:1599:78: F821 undefined name 'x'
Lib/test/test_shutil.py:1602:48: F821 undefined name 'x'
Lib/test/test_urllib2net.py:60:23: F821 undefined name 'ResourceDenied'
Lib/test/test_importlib/test_threaded_import.py:275:5: F821 undefined name 'unittets'
Lib/test/test_sqlite3/test_dbapi.py:312:13: F821 undefined name 'const'
Lib/test/test_sqlite3/test_dbapi.py:646:39: F821 undefined name 'size'

Lib/enum.py:483:30: F523 '...'.format(...) has unused arguments at position(s): 0
Lib/test/test_concurrent_futures.py:480:47: F522 '...'.format(...) has unused named argument(s): executor_type

Lib/encodings/mac_arabic.py:474:5: F601 dictionary key 32 repeated with different values
[...]
Lib/encodings/mac_arabic.py:593:5: F601 dictionary key 125 repeated with different values
Lib/test/test_mailbox.py:2265:5: F601 dictionary key 'Delivered-To' repeated with different values
Lib/test/test_mailbox.py:2266:5: F601 dictionary key 'Received' repeated with different values
[...]