tp_as_{number,sequence,mapping} can't be set using PyType_FromSpec

[awilkins]

BPO	13115
Nosy	@loewis, @amauryfa

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2014-01-04.10:37:30.003>
created_at = <Date 2011-10-06.14:10:25.949>
labels = ['interpreter-core', 'type-bug']
title = "tp_as_{number,sequence,mapping} can't be set using PyType_FromSpec"
updated_at = <Date 2014-01-04.10:37:30.001>
user = 'https://bugs.python.org/awilkins'

bugs.python.org fields:

activity = <Date 2014-01-04.10:37:30.001>
actor = 'loewis'
assignee = 'none'
closed = True
closed_date = <Date 2014-01-04.10:37:30.003>
closer = 'loewis'
components = ['Interpreter Core']
creation = <Date 2011-10-06.14:10:25.949>
creator = 'awilkins'
dependencies = []
files = []
hgrepos = []
issue_num = 13115
keywords = []
message_count = 3.0
messages = ['145013', '163680', '207280']
nosy_count = 3.0
nosy_names = ['loewis', 'amaury.forgeotdarc', 'awilkins']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue13115'
versions = ['Python 3.2', 'Python 3.3']

[awilkins]

I've written an extension using Py_LIMITED_API, and I've created a type using PyType_FromSpec with the slot "Py_sq_length" defined. The slot is not being picked up, i.e. len(MyType()) fails. I can see that tp_as_sequence has not been set, which explains why. All is well if I set it manually (without Py_LIMITED_API defined), like so:
MyType->tp_as_sequence = &((PyHeapTypeObject*)MyType)->as_sequence;

As far as I can see (docs are lacking), there's no way of setting tp_as_number, tp_as_sequence or tp_as_mapping in types created with PyType_FromSpec. I would expect the presence of any Py_sq_* slots to set tp_as_sequence (likewise for number and mapping).

[loewis]

For 3.3, this is fixed in bb6df3781edb. However, this needs to be backported to 3.2.

[loewis]

Since 3.2 has seen its last bugfix release, this won't be added to 3.2 anymore.