[ty] Infer type for implicit self parameters in method bodies
#20922
+325
−210
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Diagnostic diff on typing conformance testsChanges were detected when running ty on typing conformance tests--- old-output.txt 2025-10-23 07:17:38.427123571 +0000
+++ new-output.txt 2025-10-23 07:17:41.924130267 +0000
@@ -1,5 +1,5 @@
fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_type_statement.py`: `PEP695TypeAliasType < 'db >::value_type_(Id(d817)): execute: too many cycle iterations`
-fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(17c43)): execute: too many cycle iterations`
+fatal[panic] Panicked at /home/runner/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/ef9f932/src/function/execute.rs:402:17 when checking `/home/runner/work/ruff/ruff/typing/conformance/tests/aliases_typealiastype.py`: `infer_definition_types(Id(18043)): execute: too many cycle iterations`
_directives_deprecated_library.py:15:31: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `int`
_directives_deprecated_library.py:30:26: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `str`
_directives_deprecated_library.py:36:41: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `Self@__add__`
@@ -352,6 +352,7 @@
enums_member_names.py:30:5: error[type-assertion-failure] Argument does not have asserted type `Literal["RED", "BLUE", "GREEN"]`
enums_member_values.py:30:5: error[type-assertion-failure] Argument does not have asserted type `Literal[1, 2, 3]`
enums_member_values.py:54:1: error[type-assertion-failure] Argument does not have asserted type `Literal[1]`
+enums_member_values.py:85:9: error[invalid-assignment] Object of type `int` is not assignable to attribute `_value_` of type `str`
enums_member_values.py:96:1: error[type-assertion-failure] Argument does not have asserted type `int`
enums_members.py:128:21: info[revealed-type] Revealed type: `Unknown | Literal[2]`
enums_members.py:129:9: error[type-assertion-failure] Argument does not have asserted type `Unknown`
@@ -445,7 +446,6 @@
generics_self_advanced.py:18:1: error[type-assertion-failure] Argument does not have asserted type `ParentA`
generics_self_advanced.py:19:1: error[type-assertion-failure] Argument does not have asserted type `ChildA`
generics_self_advanced.py:28:25: error[invalid-return-type] Function always implicitly returns `None`, which is not assignable to return type `Self@method1`
-generics_self_advanced.py:35:9: error[type-assertion-failure] Argument does not have asserted type `Self@method2`
generics_self_advanced.py:36:9: error[type-assertion-failure] Argument does not have asserted type `list[Self@method2]`
generics_self_advanced.py:37:9: error[type-assertion-failure] Argument does not have asserted type `Self@method2`
generics_self_advanced.py:38:9: error[type-assertion-failure] Argument does not have asserted type `Self@method2`
@@ -455,7 +455,6 @@
generics_self_attributes.py:26:33: error[invalid-argument-type] Argument is incorrect: Expected `typing.Self | None`, found `LinkedList[int]`
generics_self_attributes.py:29:5: error[invalid-assignment] Object of type `OrdinalLinkedList` is not assignable to attribute `next` of type `typing.Self | None`
generics_self_attributes.py:32:5: error[invalid-assignment] Object of type `LinkedList[int]` is not assignable to attribute `next` of type `typing.Self | None`
-generics_self_basic.py:14:9: error[type-assertion-failure] Argument does not have asserted type `Self@set_scale`
generics_self_basic.py:20:16: error[invalid-return-type] Return type does not match returned value: expected `Self@method2`, found `Shape`
generics_self_basic.py:33:16: error[invalid-return-type] Return type does not match returned value: expected `Self@cls_method2`, found `Shape`
generics_self_basic.py:54:1: error[type-assertion-failure] Argument does not have asserted type `Shape`
@@ -499,6 +498,7 @@
generics_syntax_infer_variance.py:46:1: error[invalid-assignment] Object of type `ShouldBeCovariant3[int | float]` is not assignable to `ShouldBeCovariant3[int]`
generics_syntax_infer_variance.py:74:1: error[invalid-assignment] Object of type `ShouldBeCovariant5[int]` is not assignable to `ShouldBeCovariant5[int | float]`
generics_syntax_infer_variance.py:75:1: error[invalid-assignment] Object of type `ShouldBeCovariant5[int | float]` is not assignable to `ShouldBeCovariant5[int]`
+generics_syntax_infer_variance.py:82:9: error[invalid-assignment] Cannot assign to final attribute `x` on type `Self@__init__`
generics_syntax_infer_variance.py:85:1: error[invalid-assignment] Object of type `ShouldBeCovariant6[int]` is not assignable to `ShouldBeCovariant6[int | float]`
generics_syntax_infer_variance.py:86:1: error[invalid-assignment] Object of type `ShouldBeCovariant6[int | float]` is not assignable to `ShouldBeCovariant6[int]`
generics_syntax_infer_variance.py:102:1: error[invalid-assignment] Object of type `ShouldBeInvariant1[int]` is not assignable to `ShouldBeInvariant1[int | float]`
@@ -764,6 +764,8 @@
protocols_definition.py:287:1: error[invalid-assignment] Object of type `Concrete5_Bad3` is not assignable to `Template5`
protocols_definition.py:288:1: error[invalid-assignment] Object of type `Concrete5_Bad4` is not assignable to `Template5`
protocols_definition.py:289:1: error[invalid-assignment] Object of type `Concrete5_Bad5` is not assignable to `Template5`
+protocols_explicit.py:56:9: error[invalid-assignment] Object of type `tuple[int, int, str]` is not assignable to attribute `rgb` of type `tuple[int, int, int]`
+protocols_explicit.py:85:9: error[invalid-attribute-access] Cannot assign to ClassVar `cm1` from an instance of type `Self@__init__`
protocols_generic.py:40:1: error[invalid-assignment] Object of type `Concrete1` is not assignable to `Proto1[int, str]`
protocols_generic.py:56:5: error[invalid-assignment] Object of type `Box[int | float]` is not assignable to `Box[int]`
protocols_generic.py:66:5: error[invalid-assignment] Object of type `Sender[int]` is not assignable to `Sender[int | float]`
@@ -808,6 +810,11 @@
qualifiers_annotated.py:64:8: error[invalid-type-form] Special form `typing.Annotated` expected at least 2 arguments (one type and at least one metadata element)
qualifiers_annotated.py:91:1: error[call-non-callable] Object of type `typing.Annotated` is not callable
qualifiers_final_annotation.py:18:7: error[invalid-type-form] Type qualifier `typing.Final` expected exactly 1 argument, got 2
+qualifiers_final_annotation.py:52:9: error[invalid-assignment] Cannot assign to final attribute `ID4` on type `Self@__init__`
+qualifiers_final_annotation.py:54:9: error[invalid-assignment] Cannot assign to final attribute `ID5` on type `Self@__init__`
+qualifiers_final_annotation.py:57:13: error[invalid-assignment] Cannot assign to final attribute `ID6` on type `Self@__init__`
+qualifiers_final_annotation.py:59:13: error[invalid-assignment] Cannot assign to final attribute `ID6` on type `Self@__init__`
+qualifiers_final_annotation.py:65:9: error[invalid-assignment] Cannot assign to final attribute `ID7` on type `Self@method1`
qualifiers_final_annotation.py:71:1: error[invalid-assignment] Reassignment of `Final` symbol `RATE` is not allowed: Symbol later reassigned here
qualifiers_final_annotation.py:81:1: error[invalid-assignment] Cannot assign to final attribute `DEFAULT_ID` on type `<class 'ClassB'>`
qualifiers_final_annotation.py:118:9: error[invalid-type-form] Type qualifier `typing.Final` is not allowed in type expressions (only in annotation expressions)
@@ -915,5 +922,5 @@
typeddicts_usage.py:28:17: error[missing-typed-dict-key] Missing required key 'name' in TypedDict `Movie` constructor
typeddicts_usage.py:28:18: error[invalid-key] Invalid key access on TypedDict `Movie`: Unknown key "title"
typeddicts_usage.py:40:24: error[invalid-type-form] The special form `typing.TypedDict` is not allowed in type expressions. Did you mean to use a concrete TypedDict or `collections.abc.Mapping[str, object]` instead?
-Found 917 diagnostics
+Found 924 diagnostics
WARN A fatal error occurred while checking some files. Not all project files were analyzed. See the diagnostics list above for details. |
sharkdp
commented
Oct 16, 2025
|
|
||
| class ThisFails: | ||
| def __init__(self): | ||
| # error: [invalid-assignment] "Implicit shadowing of function `__getattribute__`" |
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Probably something we should look at or create an issue for.
|
| Lint rule | Added | Removed | Changed |
|---|---|---|---|
unresolved-attribute |
5,931 | 0 | 0 |
possibly-missing-attribute |
3,292 | 8 | 21 |
invalid-argument-type |
1,989 | 6 | 117 |
unused-ignore-comment |
0 | 1,115 | 0 |
unsupported-operator |
939 | 2 | 5 |
invalid-assignment |
496 | 8 | 15 |
invalid-return-type |
386 | 74 | 14 |
non-subscriptable |
413 | 0 | 0 |
call-non-callable |
220 | 0 | 0 |
too-many-positional-arguments |
174 | 0 | 0 |
not-iterable |
130 | 0 | 0 |
no-matching-overload |
120 | 0 | 0 |
missing-argument |
114 | 0 | 0 |
possibly-missing-implicit-call |
92 | 4 | 10 |
unknown-argument |
66 | 0 | 0 |
deprecated |
28 | 0 | 0 |
parameter-already-assigned |
17 | 4 | 0 |
possibly-unresolved-reference |
0 | 19 | 0 |
redundant-cast |
18 | 0 | 0 |
division-by-zero |
6 | 4 | 0 |
index-out-of-bounds |
6 | 0 | 0 |
invalid-await |
4 | 0 | 1 |
invalid-context-manager |
3 | 0 | 0 |
type-assertion-failure |
0 | 3 | 0 |
invalid-attribute-access |
2 | 0 | 0 |
invalid-key |
2 | 0 | 0 |
missing-typed-dict-key |
2 | 0 | 0 |
unsupported-base |
2 | 0 | 0 |
invalid-parameter-default |
1 | 0 | 0 |
invalid-super-argument |
1 | 0 | 0 |
invalid-type-form |
1 | 0 | 0 |
| Total | 14,455 | 1,247 | 183 |
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CodSpeed Performance ReportMerging #20922 will degrade performances by 16.56%Comparing Summary
Benchmarks breakdown
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sharkdp
commented
Oct 22, 2025
sharkdp
commented
Oct 22, 2025
sharkdp
requested review from
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dcreager
as code owners
MichaReiser
approved these changes
Oct 22, 2025
| .node(&module) | ||
| .parameters | ||
| .index(parameter.name()) | ||
| .is_some_and(|index| index != 0) |
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Should we also return here if the function has no parameter named parameter.name (which should never happen?)
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Or alternatively, can we pass the parameter index into infer_parameter_definition, and only call this method for the first parameter? Then we don't have to look up by name, and we don't have to verify that what we found was parameter 0.
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can we pass the parameter index into infer_parameter_definition
I see no way of doing that, unfortunately. The AST doesn't store the index of the parameter.
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It looks like element_offset is stabilizing soon — so in some number of months we'll be able to get the parameter index from the function's parameter slice without threading it through explicitly!
dcreager
approved these changes
Oct 22, 2025
| .node(&module) | ||
| .parameters | ||
| .index(parameter.name()) | ||
| .is_some_and(|index| index != 0) |
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Or alternatively, can we pass the parameter index into infer_parameter_definition, and only call this method for the first parameter? Then we don't have to look up by name, and we don't have to verify that what we found was parameter 0.
Part of astral-sh/ty#159 Add support for adding a synthetic `typing.Self` type for `self` arguments in methods. `typing.Self` is assigned as the type if there are no annotations. - Updated md tests. --------- Co-authored-by: David Peter <mail@david-peter.de>
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Summary
Infer a type of
Selffor unannotatedselfparameters in methods of classes.part of astral-sh/ty#159
closes astral-sh/ty#1081
Conformance tests changes
+enums_member_values.py:85:9: error[invalid-assignment] Object of type `int` is not assignable to attribute `_value_` of type `str`A true positive ✔️
Two false positives going away ✔️
+generics_syntax_infer_variance.py:82:9: error[invalid-assignment] Cannot assign to final attribute `x` on type `Self@__init__`This looks like a true positive to me, even if it's not marked with
# E✔️+protocols_explicit.py:56:9: error[invalid-assignment] Object of type `tuple[int, int, str]` is not assignable to attribute `rgb` of type `tuple[int, int, int]`True positive ✔️
This looks like a true positive to me, even if it's not marked with
# E. But this is consistent with our understanding ofClassVar, I think. ✔️New true positives ✔️
This is a new false positive, but that's a pre-existing issue on main (if you annotate with
Self): https://play.ty.dev/3ee1c56d-7e13-43bb-811a-7a81e236e6ab ❌ => reported as astral-sh/ty#1409Ecosystem
unresolved-attributeand 3292 newpossibly-missing-attributeattribute errors, way too many to look at all of them. I randomly sampled 15 of these errors and found:setattrdynamicness going on. I would consider all of them to be true positives.objin__new__, which we don't support yet__slots__Finalinstance attributes being set in__init__. I don't think this should block this PR.Test Plan
New Markdown tests.