PyArg_Parse* should raise TypeError for float parsed with integer format

[mdickinson]

BPO	5080
Nosy	@birkenfeld, @mdickinson, @pitrou, @vstinner, @ezio-melotti
Files	issue5080.patch

^{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 = 'https://github.com/mdickinson'
closed_at = <Date 2010-01-01.19:30:02.485>
created_at = <Date 2009-01-27.12:23:56.157>
labels = ['type-bug']
title = 'PyArg_Parse* should raise TypeError for float parsed with integer format'
updated_at = <Date 2010-01-01.19:30:02.484>
user = 'https://github.com/mdickinson'

bugs.python.org fields:

activity = <Date 2010-01-01.19:30:02.484>
actor = 'mark.dickinson'
assignee = 'mark.dickinson'
closed = True
closed_date = <Date 2010-01-01.19:30:02.485>
closer = 'mark.dickinson'
components = []
creation = <Date 2009-01-27.12:23:56.157>
creator = 'mark.dickinson'
dependencies = []
files = ['15649']
hgrepos = []
issue_num = 5080
keywords = ['patch']
message_count = 11.0
messages = ['80649', '92239', '92400', '95497', '95538', '95541', '96689', '96692', '96751', '97118', '97120']
nosy_count = 6.0
nosy_names = ['georg.brandl', 'mark.dickinson', 'pitrou', 'vstinner', 'ezio.melotti', 'marcin.wider']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue5080'
versions = ['Python 2.7', 'Python 3.2']

[mdickinson]

Since Python 2.3, PyArg_ParseTuple and friends give a DeprecationWarning
for floating-point arguments where integers are expected. From
http://www.python.org/download/releases/2.3/NEWS.txt:

• The PyArg_Parse functions now issue a DeprecationWarning if a float
  argument is provided when an integer is specified (this affects the 'b',
  'B', 'h', 'H', 'i', and 'l' codes). Future versions of Python will
  raise a TypeError.

Can we turn that DeprecationWarning into a TypeError for 2.7? (It's
already a TypeError in 3.x.) I'd like to see things like 'range(-0.3)'
and 'itertools.combinations(range(3), 5.1)' raise TypeError.

N.B. The relevant format codes in 2.7 include 'I' and 'n' in addition to
the six codes listed above.

[birkenfeld]

+1.

[vstinner]

+10. It would fix the os.urandom(1.2) bug. On Linux, os.urandom() displays
the following warnings and then go into an unlimited loop...

/usr/lib/python2.5/os.py:734: DeprecationWarning: integer argument expected,
got float
bytes += read(_urandomfd, n - len(bytes))

read(1.2 - 1) ~> read(0.2) ~> read(0)...

Tolerate float as integers introduces "subtle" bugs like byte/unicode bugs...

[pitrou]

+1 for a TypeError too.

[pitrou]

I think this should be signalled on the mailing-list, by the way. I
expect everyone to agree of course :)

[mdickinson]

Yes, checking with python-dev sounds sensible. I'll wait until there's
a working patch, though.

[mdickinson]

Hmm. That's unfortunate: for argument type in 'bBHiIlkKn', an attempt to
pass a float results in a DeprecationWarning. For type 'L', there's no
DeprecationWarning, and the float is silently truncated. So for type 'L'
I guess we still have to go through a round of DeprecationWarning.

I'm not sure what 'h' does; there don't appear to be any tests for it,
currently.

[mdickinson]

'h' also produces a DeprecationWarning; I just added the missing tests
for it in r76930 (trunk) and r76931 (py3k).

[mdickinson]

Here's a patch that makes the DeprecationWarning a TypeError, and adds a
new DeprecationWarning for the 'L' format.

[mdickinson]

Applied to trunk in r77218. The DeprecationWarning for the 'L' format
needs to be merged to py3k.

[mdickinson]

Merged relevant bits to py3k in r77220.