Different behaviour of regexp in 3.6.0b2

[Chris Angelico]

On Sat, Oct 15, 2016 at 4:48 AM, Ned Batchelder <ned at nedbatchelder.com> wrote:
> On Friday, October 14, 2016 at 1:27:09 PM UTC-4, Chris Angelico wrote:
>> On Sat, Oct 15, 2016 at 4:12 AM, Ned Batchelder <ned at nedbatchelder.com> wrote:
>> > There doesn't seem to be a change to string literals at all. It's only a
>> > change in the regex engine.
>> >
>> >     Python 3.6.0b2 (default, Oct 10 2016, 21:30:05)
>> >     [GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
>> >     Type "help", "copyright", "credits" or "license" for more information.
>> >     >>> "\s"
>> >     '\\s'
>>
>> Try with -Wall. To avoid breaking every novice Windows program ever
>> written (bar two or three), it's only a warning for now.
>
> I see. I'm not sure how novice users will know to enable warnings that are
> off by default.  Do people regularly run their code with -Wall? I never have,
> and I don't know how I would have seen these warnings.

Tools like ipython can choose to enable warnings by default. I'm not
sure if they do or not, but it'd be a good thing.

ChrisA