compile() doesn't work on ImportFrom with level=None

[JanoschGrf]

BPO	13436
Nosy	@terryjreedy, @amauryfa, @vstinner, @benjaminp, @berkerpeksag
Files	issue13436.patch issue13436.py

^{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 2016-04-29.16:50:20.729>
created_at = <Date 2011-11-20.00:04:38.730>
labels = ['interpreter-core', 'type-bug']
title = "compile() doesn't work on ImportFrom with level=None"
updated_at = <Date 2016-04-29.16:50:20.728>
user = 'https://bugs.python.org/JanoschGrf'

bugs.python.org fields:

activity = <Date 2016-04-29.16:50:20.728>
actor = 'berker.peksag'
assignee = 'none'
closed = True
closed_date = <Date 2016-04-29.16:50:20.729>
closer = 'berker.peksag'
components = ['Interpreter Core']
creation = <Date 2011-11-20.00:04:38.730>
creator = 'Janosch.Gr\xc3\xa4f'
dependencies = []
files = ['23739', '42653']
hgrepos = []
issue_num = 13436
keywords = ['patch']
message_count = 8.0
messages = ['147972', '148007', '148020', '148143', '148144', '148371', '264509', '264511']
nosy_count = 7.0
nosy_names = ['terry.reedy', 'amaury.forgeotdarc', 'vstinner', 'benjamin.peterson', 'python-dev', 'berker.peksag', 'Janosch.Gr\xc3\xa4f']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue13436'
versions = ['Python 3.2', 'Python 3.3']

[JanoschGrf]

The documentation for ast says that arguments that are marked with a '?' in the abstract grammar are optional and can therefore be None.
When I try to compile a Module node which contains an ImportFrom node with attribute level=None compile() throws an exception:

Module(body=[ImportFrom(module='time', names=[alias(name='sleep', asname=None), alias(name='time', asname=None)], level=None, lineno=0, col_offset=0)])

Traceback (most recent call last):
  File "g0.py", line 423, in <module>
    p.main()
  File "g0.py", line 65, in main
    self.reproduce("g1.pyc")
  File "g0.py", line 85, in reproduce
    co = self.generate_bytecode(st, genome)
  File "g0.py", line 243, in generate_bytecode
    co = compile(st, id, "exec")
ValueError: invalid integer value: ��������

So, I tried to set level=0:
Module(body=[ImportFrom(module='time', names=[alias(name='sleep', asname=None), alias(name='time', asname=None)], level=0, lineno=0, col_offset=0)])

and everything worked fine.

BTW: The unprintable bytes in the error message are:
ef bf bd ef bf bd ef bf bd ef bf bd ef bf bd ef bf bd ef bf bd ef bf bd

[amauryfa]

Here is a patch for the bad error message (PyBytes_AS_BYTES after PyObject_Repr, bah)

[benjaminp]

LGTM.

[python-dev]

New changeset ffcdfc534942 by Amaury Forgeot d'Arc in branch '3.2':
Issue bpo-13436: Fix a bogus error message when an AST object was passed
http://hg.python.org/cpython/rev/ffcdfc534942

New changeset 470f7d7c57ce by Amaury Forgeot d'Arc in branch '3.2':
Issue bpo-13436: commit regenerated Python-ast.c
http://hg.python.org/cpython/rev/470f7d7c57ce

[amauryfa]

I fixed the bogus error message, but "level=None" is still not allowed, whereas the docs promise that optional values can be None.

[terryjreedy]

Does this apply to 2.7 as well?

I believe msg148146 is due to a commit message typo.

[berkerpeksag]

level=None is now allowed: https://hg.python.org/cpython/file/default/Python/Python-ast.c#l5224 (see line 5224 to 5232) I converted the example in msg147972 to a Python script. test_bad_integer is still useful as it uses the required 'lineno' field. I will also commit issue13436.py as a test case.

[python-dev]

New changeset 59638baee25e by Berker Peksag in branch 'default':
Issue bpo-13436: Add a test to make sure that ast.ImportFrom(level=None) works
https://hg.python.org/cpython/rev/59638baee25e