django.utils.text.smart_strip does not work with lazy strings (TypeError)

[Baptiste Mispelon]

>>> from django.utils.text import smart_split
>>> from django.utils.translation import ugettext_lazy as _
>>> smart_split(_('a b c d'))
<django.utils.functional.lazy.<locals>.__proxy__ object at 0x7f53e20b0e10>
>>> list(smart_split(_('a b c d')))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "./django/utils/functional.py", line 128, in __wrapper__
    raise TypeError("Lazy object returned unexpected type.")
TypeError: Lazy object returned unexpected type.

This is caused by this line: ​https://github.com/django/django/blob/master/django/utils/text.py#L359

I don't think the allow_lazy decorator can be applied to a generator function so I think the line should be removed altogether.

If we remove the decorator, then lazy strings are evaluated when the generator is called.
This is not exactly backwards-incompatible since this function never actually worked with lazy strings in the first place.

[Claude Paroz]

+1 to remove allow_lazy here. As soon as you begin to manipulate strings with splitting and such, the lazyness of the string has to be dropped anyway, in my opinion. The fact that the issue didn't emerge until now is also a good sign that the functionality is not so crucial.

[Baptiste Mispelon]

I've prepared a pull request for this ticket that include fixes for 3 other ones: ​https://github.com/django/django/pull/1007

[Claude Paroz <claude@…>]

In e7b9c11c3f87e235e643c340d38325fbd4257047:

Fixed #20231 -- Don't use allow_lazy on smart_split