specialized PRECALL opcodes don't check types

[sweeneyde]

On the main branch, on both Windows and Linux, this crashes:

class Thing:
    pass

thing = Thing()

for i in range(10):
    print(i)
    try:
        str.upper(thing)
    except TypeError:
        pass

print("ok")

Other methods like str.split, bytes.split, and list.sort fail similarly. I caught this by running

./python -m test test_descr -m test_proxy_call -R3:20

Looking through stack traces, it appears the failure is on the res = cfunc(...) call in PRECALL_METHOD_DESCRIPTOR_FAST_WITH_KEYWORDS instruction. It looks to be a 3.11-only bug.

[sweeneyde]

If we're trying to emulate method_vectorcall_FASTCALL_KEYWORDS, then we're at least missing out on how method_check_args calls descr_check, which calls PyObject_TypeCheck(obj, descr->d_type). So we need one of these:

DEOPT_IF(!PyObject_TypeCheck(PEEK(nargs), callable->d_type));

or

DEOPT_IF(!Py_IS_TYPE(PEEK(nargs), callable->d_type));

I might have an off-by-one error.

cc @Fidget-Spinner @kumaraditya303

[sweeneyde]

Marking as release blocker: it's easy to trigger but hard to reason about if you don't know about specialization, so it could create Heisenbugs, which would be unfortunate in the beta release.

[corona10]

FYI, macOS meets the same issue as expected.

[sweeneyde]

It looks like PRECALL_NO_KW_METHOD_DESCRIPTOR_NOARGS is affected as well.

[sweeneyde]

PRECALL_NO_KW_METHOD_DESCRIPTOR_O as well