New submission from STINNER Victor:
While running the test suite on issues #29259 (tp_fastcall) and #29358
(tp_fastnew and tp_fastinit), a few test failed on the following assertion of
_PyStack_AsDict():
assert(PyUnicode_CheckExact(key));
For example, test_dict calls dict(**{1: 2}) which must raise a TypeError. I'm
not sure who is responsible to check if all keys are strings:
_PyStack_AsDict(), PyArg_ParseXXX() or the final function?
The check is already implemented in dict_init(), dict_update_common() calls
PyArg_ValidateKeywordArguments():
>>> dict(**{1:2})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: keyword arguments must be strings
In Python 3.7, PyArg_ParseTupleAndKeywords(),
_PyArg_ParseTupleAndKeywordsFast() and _PyArg_ParseStackAndKeywords() and
PyArg_ValidateKeywordArguments() raise an error if a key of keyword argumens is
not a string:
if (!PyUnicode_Check(key)) {
PyErr_SetString(PyExc_TypeError,
"keywords must be strings");
return cleanreturn(0, &freelist);
}
IMHO the CALL_FUNCTION_EX instruction and the FASTCALL calling convention must
not check if all keys are string: the check must only be done in the function
(which can be a type constructor like dict_init()), for performance. Almost all
functions use one the PyArg_ParseXXX() function. Only very special cases like
dict_init() use more specific code to handle keyword arguments.
By the way, _PyObject_FastCallKeywords() already contains the following comment:
/* kwnames must only contains str strings, no subclass, and all keys must
be unique: these checks are implemented in Python/ceval.c and
_PyArg_ParseStackAndKeywords(). */
Note: Technically, I know that it's possible to put non-string keys in a
dictionary and in a type dictionary. PyPy (and other Python implementations?)
don't support non-string in type dictionary. Do you know use cases where
func(**kwargs) must accept non-string keys?
At the end, this long issue is a simple patch replacing an assertion with a
comment in _PyStack_AsDict(): see attached patch ;-)
----------
components: Interpreter Core
files: pystack_asdict.patch
keywords: patch
messages: 286157
nosy: haypo
priority: normal
severity: normal
status: open
title: Don't check if all keys are strings in _PyStack_AsDict()
versions: Python 3.7
Added file: http://bugs.python.org/file46403/pystack_asdict.patch
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue29360>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
