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The fix for bug #1119418 (xrange() builtin accepts
keyword arg silently) included in Python 2.4.2c1+
breaks code that passes keyword argument(s) into
classes derived from the built-in set class, even if
those derived classes explictly accept those keyword
arguments and avoid passing them down to the built-in
base class.
Simplified version of code in attached
BuiltinSetKeywordArgumentsCheckBroken.py fails at (G)
due to bug #1119418 if version < 2.4.2c1; if version >=
2.4.2c1 (G) passes thanks to that bug fix, but instead
(H) incorrectly-in-my-view fails.
[Presume similar cases would fail for xrange and the
other classes mentioned in #1119418.]
 -- David Bruce
(Tested on 2.4, 2.4.2, 2.5a2 on linux2, win32.)

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Raymond, what to do in this case?
Note that other built-in types, such as list(), do accept
keyword arguments.

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This bug was introduced as part of the fix for bug #1119418.
It also affects collections.deque.
Can't the _PyArg_NoKeywords check simply be moved
to set_init and deque_init as it was done for
zipimport.zipimporter?
array.array doesn't need to be changed, since it
already does all of its initialization in its
__new__ method.
The rest of the types changed in that fix should not
be affected, since they are immutable.
 

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See patch #1491939 

I prefer the approach used by list().

I'll do that, only in set_init, you have 
if (!PyArg_UnpackTuple(args, self->ob_type->tp_name, 0, 1, &iterable))
Changing this to use PyArg_ParseTupleAndKeywords would require a format string of
"|O:" + self->ob_type->tp_name
Is it worth constructing that string each time set_init() is called or should it just be "|O:set" for
sets and frozensets?

My proposed solution:
- if(!PyArg_NoKeywords("set()", kwds)
+ if(type == &PySet_Type && !PyArg_NoKeywords("set()", kwds)

I fixed setobject.c in revisions 53380 and 53381.
Please apply similar fixes to all the other places being bitten my the pervasive NoKeywords tests.

Attaching patch.
File Added: nokeywordchecks.diff

That looks about right. Please add test cases that fail without the patch and succeed with the patch. Also, put a comment in Misc/NEWS. If the whole test suite passes, go ahead and check-in to Py2.5.1 and the head. 
Thanks, 
Raymond

Were these changes applied by Raymond? I don't think there were NEWS entries though.

I'll create the testcases and commit the patch (as well as NEWS entries :) when I find the time.

Committed as rev. 53509, 53510 (2.5).

There are more of these that need to be fixed:
bufferobject.c:236: if (!_PyArg_NoKeywords("buffer()", kw))
classobject.c:2261: if (!_PyArg_NoKeywords("instancemethod", kw))
exceptions.c:57: if (!_PyArg_NoKeywords(self->ob_type->tp_name, kwds))
funcobject.c:653: if (!_PyArg_NoKeywords("classmethod", kwds))
funcobject.c:810: if (!_PyArg_NoKeywords("staticmethod", kwds))
rangeobject.c:48: if (!_PyArg_NoKeywords("xrange()", kw))
sliceobject.c:197: if (!_PyArg_NoKeywords("slice()", kw))
typeobject.c:5773: if (!_PyArg_NoKeywords("super", kwds))

The exceptions.c one is in __init__, so it is not a problem when the derived class doesn't pass along kwargs to super.__init__.
I deliberately left the others as they were since their type objects lack the Py_TPFLAGS_BASETYPE flag.

Okay, it looks like this bug was already fixed.