2to3 haven't convert buffer object to memoryview

[bhy]

BPO	5517
Nosy	@benjaminp

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

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GitHub fields:

assignee = None
closed_at = <Date 2009-03-19.11:44:04.601>
created_at = <Date 2009-03-19.07:11:00.765>
labels = ['invalid', 'type-feature', 'expert-2to3']
title = "2to3 haven't convert buffer object to memoryview"
updated_at = <Date 2009-03-19.11:44:04.442>
user = 'https://bugs.python.org/bhy'

bugs.python.org fields:

activity = <Date 2009-03-19.11:44:04.442>
actor = 'benjamin.peterson'
assignee = 'none'
closed = True
closed_date = <Date 2009-03-19.11:44:04.601>
closer = 'benjamin.peterson'
components = ['2to3 (2.x to 3.x conversion tool)']
creation = <Date 2009-03-19.07:11:00.765>
creator = 'bhy'
dependencies = []
files = []
hgrepos = []
issue_num = 5517
keywords = []
message_count = 2.0
messages = ['83802', '83806']
nosy_count = 2.0
nosy_names = ['benjamin.peterson', 'bhy']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue5517'
versions = ['Python 2.6', 'Python 3.0', 'Python 3.1', 'Python 2.7']

[bhy]

The following example is valid in Python 2.6:

a = 'abc'
b = buffer(a)
print([repr(c) for c in b])

After 2to3 it, the 'buffer' isn't changed to memoryview, so then it is
not valid program in Python 3:

Traceback (most recent call last):
  File "bufferobj3.py", line 2, in <module>
    b = buffer(a)
NameError: name 'buffer' is not defined

However even it changed to memoryview the program still not valid because:

>>> memoryview('a')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: cannot make memory view because object does not have the
buffer interface

I can reporduce this on both Python 3.0.1 and Python 3.1a1+ (py3k:70310).

Thanks!

[benjaminp]

2to3 will convert buffer to memoryview, but not by default because as
you can see, it can be wrong. (Pass "-f buffer" to 2to3.) You can only
use memoryviews on bytes-like objects like b'a', and not unicode strings
(This is like 2.x.).