trace.CoverageResult fails merging input file with non-empty callers

[glinsvad]

BPO	7275
Nosy	@berkerpeksag, @iritkatriel
Files	trace.diff: Proposed patch for out of place 'callers' argument issue7275.diff

^{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 = None
created_at = <Date 2009-11-06.18:12:00.434>
labels = ['easy', 'type-bug', '3.9', '3.10', '3.11', 'library']
title = 'CoverageResult fails to merge input file with non-empty callers in trace.py'
updated_at = <Date 2022-01-20.23:10:32.121>
user = 'https://bugs.python.org/glinsvad'

bugs.python.org fields:

activity = <Date 2022-01-20.23:10:32.121>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2009-11-06.18:12:00.434>
creator = 'glinsvad'
dependencies = []
files = ['15279', '42558']
hgrepos = []
issue_num = 7275
keywords = ['easy']
message_count = 4.0
messages = ['94991', '109980', '263925', '411054']
nosy_count = 4.0
nosy_names = ['dstanek', 'glinsvad', 'berker.peksag', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue7275'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

Linked PRs

• gh-51524: Fix bug when calling trace.CoverageResults with valid infile #99629
• [3.11] gh-51524: Fix bug when calling trace.CoverageResults with valid infile (GH-99629) #99832
• [3.10] gh-51524: Fix bug when calling trace.CoverageResults with valid infile (GH-99629) #99833

[glinsvad]

trace.CoverageResults expects arguments in the order "counts, calledfuncs,
infile, callers..." but the try statement in the last part of __init__
passes "counts, calledfuncs, callers" as positional arguments to a new
instance of the same class. Thus, the secondary instance erroneously
obtains a dict for the "infile" argument, so I propose passing "callers"
as a keyword argument to avoid this.

Not that this has gone unnoticed because an empty dict for the "infile"
argument evaluates to False in "if self.infile:", which must have been
intended as "if self.infile is not None:". If, however, the original
instance loads a pickle file with a non-empty "callers" argument, the
secondary instance tries to run "open({}, 'rb')", which yields:

TypeError: coercing to Unicode: need string or buffer, dict found

[BreamoreBoy]

The attached patch is effectively a one liner.

[berkerpeksag]

Thanks for the report and for the patch, Christian. Here is a patch with a test.

[iritkatriel]

The patch needs to be converted to a GitHub PR.

[furkanonder]

@iritkatriel I opened a PR for this issue.