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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 |
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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