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Report possibly uninitialized attributes defined in class bodies - #5344
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This pull request has been imported. If you are a Meta employee, you can view this in D127200263. (Because this pull request was imported automatically, there will not be any future comments.) |
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Diff from mypy_primer, showing the effect of this PR on open source code: ============================================================
SUMMARY
============================================================
Total: +11 new errors, -0 fixed errors
By preset: +0/-0 (default), +0/-0 (strict)
Projects with changes (7):
pycryptodome: +1 -0
urllib3: +3 -0
spark: +1 -0
pwndbg: +1 -0
pandera: +1 -0
pandas: +2 -0
dd-trace-py: +2 -0
============================================================
FULL DIFF DETAILS
------------------------------------------------------------
pycryptodome (https://github.com/Legrandin/pycryptodome)
+ ERROR lib/Crypto/SelfTest/Signature/test_dss.py:1070:9-15: Attribute `new_tv` may be uninitialized [possibly-uninitialized-attribute]
urllib3 (https://github.com/urllib3/urllib3)
+ ERROR src/urllib3/connection.py:299:9-30: Attribute `_is_legal_header_name` may be uninitialized [possibly-uninitialized-attribute]
+ ERROR src/urllib3/connection.py:300:9-33: Attribute `_is_illegal_header_value` may be uninitialized [possibly-uninitialized-attribute]
+ ERROR src/urllib3/connection.py:303:9-42: Attribute `_contains_disallowed_url_pchar_re` may be uninitialized [possibly-uninitialized-attribute]
spark (https://github.com/apache/spark)
+ ERROR python/pyspark/testing/connectutils.py:68:15-21: Attribute `MockDF` may be uninitialized [possibly-uninitialized-attribute]
pwndbg (https://github.com/pwndbg/pwndbg)
+ ERROR pwndbg/gdblib/tui/context.py:219:9-23: Attribute `___ansi_substr` may be uninitialized [possibly-uninitialized-attribute]
pandera (https://github.com/pandera-dev/pandera)
+ ERROR pandera/typing/fastapi.py:92:41-51: Attribute `ModelField` may be uninitialized [possibly-uninitialized-attribute]
pandas (https://github.com/pandas-dev/pandas)
+ ERROR pandas/io/formats/style.py:4089:17-36: Attribute `template_html_table` may be uninitialized [possibly-uninitialized-attribute]
+ ERROR pandas/io/formats/style.py:4091:17-36: Attribute `template_html_style` may be uninitialized [possibly-uninitialized-attribute]
dd-trace-py (https://github.com/DataDog/dd-trace-py)
+ ERROR ddtrace/testing/internal/pytest/plugin.py:859:9-40: Attribute `pytest_runtest_protocol_wrapper` may be uninitialized [possibly-uninitialized-attribute]
+ ERROR ddtrace/testing/internal/pytest/plugin.py:863:9-32: Attribute `pytest_runtest_protocol` may be uninitialized [possibly-uninitialized-attribute] |
meta-codesync Bot
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Summary:
A class attribute assigned in only one runtime branch is treated as always available. Add `possibly-uninitialized-attribute` at the definition when a completing class-body path lacks an assignment.
```python
class C:
if enabled():
value = 1 # possibly-uninitialized-attribute
```
The default preset ignores the new error kind, and the strict preset enables it. Users can configure it separately from `missing-attribute`. Paths that terminate with `Never` or `NoReturn`, inherited attributes, and stub files are handled. Conditionally defined methods are reported here; the next diff in the stack excludes them. Method assignments do not establish class-body initialization.
Reuse the existing class-body flow results and collect initialization checks when the class body completes.
Extracted from #4326. This PR is based directly on `main` and can land independently. The instance initialization extension remains in #4326.
- [x] I am a human, and I fully understand the code I am submitting.
X-link: #5344
Reviewed By: stroxler
Differential Revision: D127200263
Pulled By: connernilsen
fbshipit-source-id: e6854d1a65f49b4161e2becc460abc477bfdecfd
meta-codesync Bot
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Summary: Split from #5344 so the exclusion can be reviewed separately from the class-body check in the previous diff. `possibly-uninitialized-attribute` reports class-body names assigned on only some paths. A method defined under a runtime condition is usually deliberate, such as a version or platform shim, so reporting it adds noise: ```python class C: if runtime_flag(): def path(self) -> str: ... # reported by the previous diff ``` Record on each `Definition` whether every definition site of the name is a `def` statement (`function_def_only`), the same way `main_guard_only` is tracked: set at the first site and ANDed in `Definition::merge`. A `del` or any other binding of the name clears it. The flag is copied into the scope's `StaticInfo`, and a class-body name that carries it is treated as initialized. The rule is syntactic: decorated methods (`property`, `staticmethod`, `cached_property`) are exempt, while `lambda` or `staticmethod(f)` assignments are still checked. This is deliberately the simple rule rather than a semantic one: a conditional `f = staticmethod(g)` or `f = lambda self: 1` is just as deliberate as a conditional `def`, but telling such assignments apart from data attributes would need type information that isn't available when bindings are built. Handling them would mean ad hoc syntactic special cases or a type-based check at solve time; the syntactic rule is much simpler, predictable, and the rare conditional lambda method can be written as a `def`. Conditions on `sys.version_info` and `sys.platform` are evaluated statically, so methods defined under them were never reported. Differential Revision: D127870321 Pulled By: connernilsen fbshipit-source-id: 70be9926ca354b0d81d36efee7b80b3da14a0744
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This is confusing, the mirrored diff D127200263 is merged, but the PR didn't auto-close. I suspect the link was somehow lost in the diff metadata :( Closing now - note that if you had improvements that are still relevant, you could open a new PR against trunk |
meta-codesync Bot
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…hods Summary: Builds on D127200263 (#5344), which adds `possibly-uninitialized-attribute` for class-body attributes. Fixes #4318. Extend `possibly-uninitialized-attribute` to instance attributes. An attribute assigned in a recognized initialization method, such as `__init__`, is reported at its definition when the method can complete without assigning it. The default preset still ignores the check, and the strict preset enables it. The previous diffs compute, for each method, whether each attribute is assigned on every path. This diff uses the status from the first method that assigns the attribute, which is a recognized initialization method such as `__init__` when there is one, and reports the attribute when that status does not prove initialization. Paths that raise do not need an assignment, and neither does the end of a method when it is unreachable, such as after a loop that always runs and always returns. Attributes defined only in unrecognized methods, stub files, and inherited attributes are excluded. This diff is the core of the check. The following diffs each refine one rule and update the tests that change: - `Never` and `NoReturn` calls end a path. - Loops may run zero times. - Assignments in nested functions do not initialize the attribute. - A bare `self.x: int` annotation does not initialize the attribute. - Assignments from several methods are combined, so a helper can establish initialization. Later diffs handle paths that end in an explicit `return` (D128396279), deletions (D128396280), and `__getattr__` fallbacks (D128396281). Until then, the tests mark the resulting false negatives and false positives with `bug`. D128396273 prepares the class field representation for this change. The tests are in D127830364, which marks the unsupported cases with `bug`. This diff removes the markers for the cases it fixes and relabels the markers for the cases that later diffs fix. X-link: #4326 Reviewed By: kinto0 Differential Revision: D113913556 Pulled By: connernilsen fbshipit-source-id: 0cd51cf3ee4d9dea2e5faa56144ba9977bf99dd7
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Summary
A class attribute assigned in only one runtime branch is treated as always available. Add
possibly-uninitialized-attributeat the definition when a completing class-body path lacks an assignment.The default preset ignores the new error kind, and the strict preset enables it. Users can configure it separately from
missing-attribute. Paths that terminate withNeverorNoReturn, inherited attributes, conditional method definitions, and stub files are handled. Method assignments do not establish class-body initialization.Reuse the existing class-body flow results and collect initialization checks when the class body completes.
Extracted from #4326. This PR is based directly on
mainand can land independently. The instance initialization extension remains in #4326.Test Plan