Issue 32231: -bb option should override -W options (original) (raw)
Created on 2017-12-06 10:43 by ncoghlan, last changed 2022-04-11 14:58 by admin. This issue is now closed.
Messages (6)
Author: Alyssa Coghlan (ncoghlan) * 
Date: 2017-12-06 10:43
When implementing the "-X dev" mode, Victor was asked to make it behave differently from "-Wd", such that "python -bb -X dev" would still raise errors for bytes comparisons.
I don't think making "-X dev" and "-Wd" inconsistent with each other is the right way to address that request. Instead, I think we should find a way to make "-bb" always take precedence over any supplied "-W" options.
One way to do that would be to adopt an approach similar to what I've proposed for "-X dev" in https://bugs.python.org/issue32230: instead of making the warnings module aware of the "-bb" setting, we'd instead adjust the initialisation code to inject "error::BytesWarning" into sys.warnoptions after all of the entries from environment variables and the command line.
Author: Alyssa Coghlan (ncoghlan) *
Date: 2017-12-06 10:52
(From the discussion at https://bugs.python.org/issue32230#msg307721)
Another benefit we'd gain from this approach is that we could easily omit the filter entirely in the case where neither -b nor -bb is set: in those situations, BytesWarning won't be emitted at all, so we don't really need to define a filter for it.
Author: STINNER Victor (vstinner) *
Date: 2017-12-06 11:04
IMHO the root issue is that there are different options which set warnings filters:
- PYTHONWARNINGS/-W will fill sys.warnoptions
- sys.flags.bytes_warning (-b, -bb) and sys.flags.dev_mode (-X dev, PYTHONDEVMODE=1) which change the default filters
vstinner@apu$ ./python -W default -b -c 'import pprint, sys, warnings; pprint.pprint(warnings.filters); pprint.pprint(sys.warnoptions)' [('default', None, <class 'Warning'>, None, 0), ('default', None, <class 'BytesWarning'>, None, 0), ('default', None, <class 'ResourceWarning'>, None, 0)] ['default']
Why default::BytesWarning isn't in sys.warnoptions?
I suggest to experiment to create all filters at once in a single list, rather than having sys.warnoptions on one side and init_filters() (Python/_warnings.c) on another side.
It was on my TODO list for the PEP 432 :-) Currently, when Python is embedded, it's not easy to control filters created by init_filters() which can be an issue. I expect a feature like Py_SetPath() to override all warnings filters, not only "add" filters on top on existing filters, for the specific case of embedded Python.
Author: Alyssa Coghlan (ncoghlan) *
Date: 2017-12-06 11:12
I'm hesitant to put the true default filters in sys.warnoptions, as folks use "bool(sys.warnoptions)" as a check for "Were any warning options set via the environment or the command line?", and we don't want to invalidate that use case.
However, I'm definitely a fan of having the warnings module only look at sys.warnoptions, and requiring all command line options to route their filter settings through that channel.
https://bugs.python.org/issue32230 adjusts "-X dev" to work that way, and I'm suggesting we do the same here for "-b".
That way, we can fully define the relative ordering of PYTHONWARNINGS, "-X dev", "-W", and "-b" inside pymain_add_warnings_options (and only the true default filters will be appended by the warnings module itself).
Author: Alyssa Coghlan (ncoghlan) *
Date: 2017-12-06 11:37
One potential complication here is that embedding applications would inherit the requirement to do both:
Py_BytesWarningFlag = 2;and
PySys_AddWarnOption(L"error::BytesWarning");to request errors. That's probably OK though, since we're getting into pretty esoteric configuration behaviour at that point.
Author: Serhiy Storchaka (serhiy.storchaka) *
Date: 2017-12-06 11:47
This looks like a duplicate of .
History
Date
User
Action
Args
2022-04-11 14:58:55
admin
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github: 76412
2019-05-15 02:10:47
vstinner
set
status: open -> closed
stage: needs patch -> resolved
2017-12-06 11:47:47
serhiy.storchaka
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nosy: + serhiy.storchaka
messages: +
resolution: duplicate
2017-12-06 11:37:14
ncoghlan
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messages: +
2017-12-06 11:12:24
ncoghlan
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messages: +
2017-12-06 11:04:32
vstinner
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messages: +
2017-12-06 10:52:25
ncoghlan
set
messages: +
2017-12-06 10:43:15
ncoghlan
create