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Diagnose instance methods missing a positional receiver - #5425

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mangeshraut712:fix/5295-instance-method-missing-self
Open

Diagnose instance methods missing a positional receiver#5425
mangeshraut712 wants to merge 5 commits into
meta:mainfrom
mangeshraut712:fix/5295-instance-method-missing-self

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@mangeshraut712 mangeshraut712 commented Oct 28, 2026

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Summary

Instance methods with no positional parameter (and no *args) were accepted without a definition error. Classmethods without a receiver are covered separately in #5388 / #5294; this PR handles the instance-method case from #5295.

After decorator handling, if the method still looks like a normal instance method (self_type is set, not classmethod/staticmethod/@no_type_check, no remaining custom decorators) and has no posonly/args/*vararg, emit bad-function-definition.

Fixes #5295

  • I am a human, and I fully understand the code I am submitting.

Test Plan

  • Added test_instance_method_missing_receiver and test_instance_method_missing_receiver_decorators in attributes.rs (covers kwargs-only / keyword-only / recognized vs custom decorators).
  • Updated expected errors in existing fixtures that already defined bare instance methods (attributes, callable, class_overrides, constructors, abstract_methods, narrow, descriptors).
  • cargo test -p pyrefly --lib -- test::attributes:: test::descriptors::test_self_referential test::class_overrides::test_override_method_without_self test::constructors:: test::abstract_methods:: test::callable:: test::narrow::test_typeguard test::narrow::test_typeis test::decorators:: test::protocol:: — all passed.

@mangeshraut712
Diagnose instance methods missing a positional receiver
cff5a26 
Report bad-function-definition when a class instance method has no
positional parameter and no *args to accept the implicit self.
Skip classmethods, staticmethods, @no_type_check, and methods with
unresolved custom decorators that may reshape the signature.

Fixes meta#5295
@meta-cla meta-cla Bot added the cla signed label Oct 28, 2026
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This pull request has been imported. If you are a Meta employee, you can view this in D127981932. (Because this pull request was imported automatically, there will not be any future comments.)

@mangeshraut712
Fix fixtures and bench for missing-self instance method check
f3b5692 
Add self to hover_docstring and class-scope fixtures that used bare
def f(): (now bad-function-definition). Use Foo.f attribute access in
attribute_test to avoid MissingArgument. Bump nested_scopes bench
expected errors 20→23 for class-nested bare defs at depths 4/8/12.
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github-actions Bot requested a review from kinto0 October 28, 2026 09:08
@github-actions github-actions Bot added size/m and removed size/m labels Nov 1, 2026
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@mangeshraut712
Merge remote-tracking branch 'upstream/main' into fix/5295-instance-m…
dc690a8 
…ethod-missing-self

# Conflicts:
#	pyrefly/lib/alt/function.rs
@github-actions github-actions Bot added size/m and removed size/m labels Nov 2, 2026
@mangeshraut712

mangeshraut712 commented Nov 2, 2026

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Merged main (dc690a8). Upstream's new classmethod receiver check sat in the same block, so both checks are kept, with the classmethod one first.

About the mypy_primer diff: 105 of the 107 new errors are zope.interface Interface classes (zope.interface itself, plus scrapy/interfaces.py). Those declare methods without self on purpose, because the interface describes the method as seen from an instance. The other two (pywin32 NotifyChanged, cvxpy _cylp_checks_isProvenInfeasible) look like real bugs. I can skip classes that inherit from zope.interface.Interface if you want that special case here, or keep the check plain and let zope users suppress it. Which do you prefer?

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@rchen152 rchen152 added size/s and removed size/m labels Nov 2, 2026
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Diff from mypy_primer, showing the effect of this PR on open source code:

============================================================
SUMMARY
============================================================
Total: +107 new errors, -0 fixed errors
By preset: +107/-0 (default), +107/-0 (strict)

Projects with changes (4):
  zope.interface: +104 -0
  pywin32: +1 -0
  scrapy: +1 -0
  cvxpy: +1 -0
============================================================

FULL DIFF DETAILS
------------------------------------------------------------

zope.interface (https://github.com/zopefoundation/zope.interface)
+ ERROR src/zope/interface/common/idatetime.py:83:9-14: Instance method `today` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:139:9-18: Instance method `timetuple` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:148:9-18: Instance method `toordinal` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:155:9-16: Instance method `weekday` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:164:9-19: Instance method `isoweekday` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:173:9-20: Instance method `isocalendar` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:192:9-18: Instance method `isoformat` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:199:9-16: Instance method `__str__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:202:9-14: Instance method `ctime` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:234:9-14: Instance method `today` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:257:9-15: Instance method `utcnow` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:343:9-13: Instance method `date` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:346:9-13: Instance method `time` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:354:9-15: Instance method `timetz` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:402:9-18: Instance method `utcoffset` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:406:9-12: Instance method `dst` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:411:9-15: Instance method `tzname` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:414:9-18: Instance method `timetuple` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:417:9-21: Instance method `utctimetuple` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:420:9-18: Instance method `toordinal` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:426:9-16: Instance method `weekday` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:433:9-19: Instance method `isoweekday` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:441:9-20: Instance method `isocalendar` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:462:9-16: Instance method `__str__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:469:9-14: Instance method `ctime` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:535:9-18: Instance method `isoformat` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:544:9-16: Instance method `__str__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:553:9-18: Instance method `utcoffset` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:563:9-12: Instance method `dst` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/idatetime.py:573:9-15: Instance method `tzname` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:83:9-13: Instance method `keys` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:87:9-17: Instance method `__iter__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:91:9-15: Instance method `values` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:95:9-14: Instance method `items` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:117:9-13: Instance method `copy` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:136:9-14: Instance method `clear` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/mapping.py:156:9-16: Instance method `popitem` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/sequence.py:158:9-16: Instance method `reverse` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/common/tests/test_collections.py:132:13-41: Instance method `FrameLocalsProxy_constructor` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:113:9-27: Instance method `getTaggedValueTags` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:144:9-33: Instance method `getDirectTaggedValueTags` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:164:9-25: Instance method `getSignatureInfo` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:181:9-27: Instance method `getSignatureString` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:399:9-17: Instance method `__iter__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:423:9-17: Instance method `__iter__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:427:9-18: Instance method `flattened` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:464:9-20: Instance method `__nonzero__` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:1250:9-28: Instance method `registeredUtilities` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:1334:9-27: Instance method `registeredAdapters` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:1425:9-39: Instance method `registeredSubscriptionAdapters` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/interfaces.py:1503:9-27: Instance method `registeredHandlers` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:140:17-24: Instance method `aMethod` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:216:17-24: Instance method `aMethod` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:241:17-24: Instance method `method1` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:244:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:252:17-24: Instance method `method3` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:255:17-24: Instance method `method4` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:258:17-24: Instance method `method5` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:385:17-24: Instance method `aMethod` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:461:17-24: Instance method `aMethod` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:486:17-24: Instance method `method1` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:489:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:497:17-24: Instance method `method3` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:500:17-24: Instance method `method4` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_document.py:503:17-24: Instance method `method5` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1418:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1445:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1474:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1508:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1569:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1589:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1618:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1630:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1636:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1639:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1655:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1678:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1684:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1687:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1742:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1763:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1769:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1772:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1811:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1832:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1838:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1841:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1879:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1892:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1898:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1901:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1924:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1936:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1942:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1945:17-24: Instance method `method2` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_interface.py:1955:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:73:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:88:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:105:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:123:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:200:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:377:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:414:17-23: Instance method `method` must accept a positional argument [bad-function-definition]
+ ERROR src/zope/interface/tests/test_verify.py:448:17-23: Instance method `method` must accept a positional argument [bad-function-definition]

pywin32 (https://github.com/mhammond/pywin32)
+ ERROR com/win32comext/axdebug/test/host.py:105:9-22: Instance method `NotifyChanged` must accept a positional argument [bad-function-definition]

scrapy (https://github.com/scrapy/scrapy)
+ ERROR scrapy/interfaces.py:21:9-13: Instance method `list` must accept a positional argument [bad-function-definition]

cvxpy (https://github.com/cvxpy/cvxpy)
+ ERROR cvxpy/tests/test_conic_solvers.py:1579:9-40: Instance method `_cylp_checks_isProvenInfeasible` must accept a positional argument [bad-function-definition]

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no error when instance method has no self parameter

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