New submission from Dan Snider <[email protected]>:
>>> class Dict(dict):
def keys(self): assert 0
def update(*args, **kwds): assert 0
def __getitem__(self, key): assert 0
def __iter__(self): assert 0
>>> {**Dict(a=1)}
{'a': 1}
The opcode uses PyDict_Update, which calls the internal dict_merge function
which contains the following line:
if (PyDict_Check(b) && (Py_TYPE(b)->tp_iter == (getiterfunc)dict_iter))
Translated to Python, that should be equal to
if type(b).__flags__ & (1<<29) and type.__getattribute__(type(b),
'__iter__') is type.__getattribute__(dict, '__iter__')`
Both that and the line in C evaluate to false for me (while a dict subclass
that doesn't override __iter__ evaluates to true), so I
apparently can't help narrow down the problem any further assuming people
agree that this is even is a problem...
The BUILD_MAP_UNPACK_WITH_CALL, CALL_FUNCTION_EX, and CALL_FUNCTION_KW opcodes
are affected as well.
----------
components: Interpreter Core
messages: 329280
nosy: bup
priority: normal
severity: normal
status: open
title: BUILD_MAP_UNPACK doesn't function as expected for dict subclasses
type: behavior
versions: Python 3.6, Python 3.7
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Python tracker <[email protected]>
<https://bugs.python.org/issue35166>
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