exceptions that can't be raised any further, because (for instance) they
occur in __del__ methods. The coroutine tests in test_generators was
triggering this leak. Remove the leakers' testcase, and add a simpler
testcase that explicitly tests this leak to test_generators.

test_generators now no longer leaks at all, on my machine. This fix may also
solve other leaks, but my full refleakhunting run is still busy, so who
knows?

slot_tp_del(), but while the latter had to cater to types
that don't participate in GC, we know that generators do.
That allows strengthing an assert().

same kind of thing.

not be tracked by GC. This fixes 254 of test_generators' refleaks on my
machine, but I'm sure something else will make them come back :>

Not adding a separate test for this kind of cycle, since the existing
fib/m235 already test them in more extensive ways than any 'minimal' test
has been able to manage.

using a custom, nearly-identical macro. This probably changes how some of
these functions are compiled, which may result in fractionally slower (or
faster) execution. Considering the nature of traversal, visiting much of the
address space in unpredictable patterns, I'd argue the code readability and
maintainability is well worth it ;P

 - In functions where we already hold the same object in differently typed
   pointers, use the correctly typed pointer instead of casting the other
   pointer a second time.

Looks like a libffi bug.

available.

tp_clear methods.

dangling references in case of a Py_Initialize/Py_Finalize
cycle.

arena's "private" list of objects, so there might
be two references to that list.

objects before initializing it. It might be linked
already if there was a Py_Initialize/Py_Finalize
cycle earlier; not unlinking it would break the global
list.

Backported to 2.4.

is a macro.

look dead right at the start.  Use Py_CLEAR for four more
frame members.

Py_VISIT:  cast the `op` argument to PyObject* when calling
`visit()`.  Else the caller has to pay too much attention to
this silly detail (e.g., frame_traverse needs to traverse
`struct _frame *` and `PyCodeObject *` pointers too).

why it's important.  Now there are ;-)

If someone else hasn't already, I'll add a Py_CLEAR cleanup
task to the TODO Wiki next.

examples no longer require any explicit closing to avoid
leaking.

That the tee-based examples still do is (I think) still a
mystery.  Part of the mystery is that gc.garbage remains
empty:  if it were the case that some generator in a trash
cycle said it needed finalization, suppressing collection
of that cycle, that generator _would_ show up in gc.garbage.

So this is acting more like, e.g., some tp_traverse slot
isn't visiting all the pointers it should (in which case
the skipped pointer(s) would act like an external root,
silently suppressing collection of everything reachable
from it(them)).

problems: first, PyGen_NeedsFinalizing() had an off-by-one bug that
prevented it from ever saying a generator didn't need finalizing, and
second, frame objects cleared themselves in a way that caused their
owning generator to think they were still executable, causing a double
deallocation of objects on the value stack if there was still a loop
on the block stack.  This revision also removes some unnecessary
close() operations from test_generators that are now appropriately
handled by the cycle collector.

PySequence_GetItem of the time.strptime() result. Not a high probability
bug, but not inconceivable either, considering people can provide their own
'time' module.

an incremental encoder that must retain part of the data between calls
to the encode() method.

Fix the incremental encoder and decoder for the IDNA encoding.

This closes SF patch #1453235.

and PyObject_DEL.