( )⚙ D11466 typing: add a fake `__init__()` to bytestr to distract pytype

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Differential D11466

typing: add a fake `__init__()` to bytestr to distract pytype
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Authored by mharbison72 on Sep 21 2021, 11:38 AM.

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rHG1fda8c9358ce: typing: add a fake `__init__()` to bytestr to distract pytype
Summary

I'm not sure what changed before pytype 09-09-2021 (from 04-15-2021), but these
started getting flagged. This wrapping an exception in a bytestr pattern has
been flagged before, and I've fixed it then with stringutil.forcebytestr().
But that doesn't work here, because it would create a circular import.

I suspect the issue is bytes.__new__() wants Iterable[int], so it just
assumes the subclass will also take that. The referenced pytype bug isn't an
exact match, but seems related and the suggested workaround helps.

The specific warnings fixed are:

File "/mnt/c/Users/Matt/hg/mercurial/encoding.py", line 212, in tolocal: Function bytestr.__init__ was called with the wrong arguments [wrong-arg-types]
         Expected: (self, ints: Iterable[int])
  Actually passed: (self, ints: LookupError)
  Attributes of protocol Iterable[int] are not implemented on LookupError: __iter__
Called from (traceback):
  line 353, in current file
File "/mnt/c/Users/Matt/hg/mercurial/encoding.py", line 240, in fromlocal: Function bytestr.__init__ was called with the wrong arguments [wrong-arg-types]
         Expected: (self, ints: Iterable[int])
  Actually passed: (self, ints: UnicodeDecodeError)
  Attributes of protocol Iterable[int] are not implemented on UnicodeDecodeError: __iter__

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Mmercurial/pycompat.py (9 lines)

Diff 30340

mercurial/pycompat.py

Be careful to not pass a bytestr object to a function which expects Be careful to not pass a bytestr object to a function which expects
bytearray-like behavior. bytearray-like behavior.
>>> t = bytes(t) # cast to bytes >>> t = bytes(t) # cast to bytes
>>> assert type(t) is bytes >>> assert type(t) is bytes
""" """
# Trick pytype into not demanding Iterable[int] be passed to __new__(),
# since the appropriate bytes format is done internally.
#
# https://github.com/google/pytype/issues/500
if TYPE_CHECKING:
def __init__(self, s=b''):
pass
def __new__(cls, s=b''): def __new__(cls, s=b''):
if isinstance(s, bytestr): if isinstance(s, bytestr):
return s return s
if not isinstance( if not isinstance(
s, (bytes, bytearray) s, (bytes, bytearray)
) and not hasattr( # hasattr-py3-only ) and not hasattr( # hasattr-py3-only
s, u'__bytes__' s, u'__bytes__'
): ):