[Python-Dev] What does a double coding cookie mean?

[Chris Angelico]

On Wed, Mar 16, 2016 at 5:03 PM, Serhiy Storchaka <storchaka at gmail.com> wrote:
> On 15.03.16 22:30, Guido van Rossum wrote:
>>
>> I came across a file that had two different coding cookies -- one on
>> the first line and one on the second. CPython uses the first, but mypy
>> happens to use the second. I couldn't find anything in the spec or
>> docs ruling out the second interpretation. Does anyone have a
>> suggestion (apart from following CPython)?
>>
>> Reference: https://github.com/python/mypy/issues/1281
>
>
> There is similar question. If a file has two different coding cookies on the
> same line, what should win? Currently the last cookie wins, in CPython
> parser, in the tokenize module, in IDLE, and in number of other code. I
> think this is a bug.

Why would you ever have two coding cookies in a file? Surely this
should be either an error, or ill-defined (ie parsers are allowed to
pick whichever they like, including raising)?

ChrisA