inspect.getsource() returns incorrect source lines at the module level

[ggenellina]

BPO	6700
Nosy	@taleinat, @devdanzin, @PCManticore, @aivarannamaa, @1st1, @jamesls, @miss-islington
PRs	bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks #8864 [3.7] bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864) #8898 [3.6] bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864) #8899 [2.7] bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864) #8900
Files	inspect.diff: patch against trunk show_inspect_bug.py issue6700.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 = None
closed_at = <Date 2018-08-26.08:47:22.187>
created_at = <Date 2009-08-14.04:19:21.635>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = 'inspect.getsource() returns incorrect source lines at the module level'
updated_at = <Date 2018-08-26.08:47:22.186>
user = 'https://bugs.python.org/ggenellina'

bugs.python.org fields:

activity = <Date 2018-08-26.08:47:22.186>
actor = 'taleinat'
assignee = 'none'
closed = True
closed_date = <Date 2018-08-26.08:47:22.187>
closer = 'taleinat'
components = ['Library (Lib)']
creation = <Date 2009-08-14.04:19:21.635>
creator = 'ggenellina'
dependencies = []
files = ['14716', '14717', '30344']
hgrepos = []
issue_num = 6700
keywords = ['patch']
message_count = 8.0
messages = ['91541', '102651', '189842', '324000', '324002', '324004', '324114', '324115']
nosy_count = 8.0
nosy_names = ['ggenellina', 'taleinat', 'ajaksu2', 'Claudiu.Popa', 'Aivar.Annamaa', 'yselivanov', 'jamesls', 'miss-islington']
pr_nums = ['8864', '8898', '8899', '8900']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue6700'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7', 'Python 3.8']

[ggenellina]

inspect.getsource(obj) returns incorrect results when obj is a
traceback or frame object outside any function (that is, at the module
level).

This demo script shows the problem. The correct output should contain
all source lines in the module, but it only returns the first two:

D:\temp>type show_inspect_bug.py
def foo(x):
return y + z

import inspect
frame = inspect.currentframe()
print inspect.getsource(frame)

D:\temp>python show_inspect_bug.py
def foo(x):
return y + z

The attached patch fixes the problem and adds some missing test cases.
Originally reported by Juanjo Conti at the local Python group.

[devdanzin]

Confirmed in trunk and py3k. Also affects inspect.getsourcelines.

[jamesls]

I confirmed the issue in tip. One of the issues with the original patch is
that it modifies the tokeneater method used by getblock which won't work
if the first token is any of the special cased tokens in the original patch
('@', 'def', 'class'). I've added additional tests that show where the
original patch fails.

An alternative approach is to check in getsourcelines whether or not we're
dealing with a traceback or frame object in the module scope, and if so,
return the lines of the entire module. I've attached an updated patch
that implements this along with additional tests.

[taleinat]

New changeset 91cb298 by Tal Einat (Vladimir Matveev) in branch 'master':
bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864)
91cb298

[miss-islington]

New changeset 0e707b4 by Miss Islington (bot) in branch '3.6':
bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864)
0e707b4

[miss-islington]

New changeset 3e6020c by Miss Islington (bot) in branch '3.7':
bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864)
3e6020c

[taleinat]

New changeset 491740f by Tal Einat in branch '2.7':
[2.7] bpo-6700: Fix inspect.getsourcelines for module level frames/tracebacks (GH-8864)
491740f

[taleinat]

Thanks for reporting this, Gabriel!

Thanks for the PR, Vladimir!