fix Resolve __call__ correctly even when it's a descriptor #254

[asukaminato0721]

Summary

Fixes #254

Implemented descriptor-aware __call__ resolution.

instance __call__ lookup now resolves through normal attribute get semantics (including descriptors/properties) via resolve_get_class_attr with an error swallower, so a descriptor’s __get__ return type is used for callability.

in as_call_target_impl, when dunder_call is true, we now re-resolve __call__ once if it doesn’t immediately recurse back to the same class, preventing false “not callable” while still guarding against infinite recursion.

Test Plan

Added a regression test for issue #254.

[Copilot]

Pull request overview

This PR fixes issue #254 where __call__ attributes defined as descriptors were not correctly resolved, causing type checkers to incorrectly report "Expected a callable" errors. The fix implements descriptor-aware __call__ resolution that properly invokes the descriptor protocol (__get__) to determine the actual callable type.

Changes:

• Introduced descriptor-aware __call__ resolution through a new resolve_dunder_call_attr helper method
• Added recursion prevention logic to handle self-referential descriptor cases safely
• Added a regression test validating that instances with descriptor __call__ attributes are properly recognized as callable

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
pyrefly/lib/test/descriptors.rs	Added regression test for descriptor __call__ resolution
pyrefly/lib/alt/class/class_field.rs	Refactored __call__ resolution methods to use descriptor-aware resolution via new resolve_dunder_call_attr helper
pyrefly/lib/alt/call.rs	Enhanced recursion prevention to allow non-self-recursive descriptor resolution while preventing infinite loops

---

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[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

dedupe (https://github.com/dedupeio/dedupe)
- ERROR dedupe/training.py:293:19-28: Expected a callable, got `Resampler` [not-callable]
- ::error file=dedupe/training.py,line=293,col=19,endLine=293,endColumn=28,title=Pyrefly not-callable::Expected a callable, got `Resampler`

werkzeug (https://github.com/pallets/werkzeug)
- ERROR tests/test_local.py:505:17-18: Expected a callable, got `LocalProxy[Any]` [not-callable]
- ::error file=tests/test_local.py,line=505,col=17,endLine=505,endColumn=18,title=Pyrefly not-callable::Expected a callable, got `LocalProxy[Any]`

jinja (https://github.com/pallets/jinja)
- ERROR tests/test_async.py:647:31-62: Cannot set item in `dict[str, ((obj: Sized, /) -> int) | ((s: Any, /) -> Markup) | ((s: Any, /) -> str) | ((env: Environment, s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: int | None = None) -> str) | ((environment: Environment, obj: Any, name: str) -> Undefined | Any) | ((environment: Environment, s: str, width: int = 79, break_long_words: bool = True, wrapstring: str | None = None, break_on_hyphens: bool = True) -> str) | ((eval_ctx: EvalContext, d: Mapping[str, Any], autospace: bool = True) -> str) | ((eval_ctx: EvalContext, s: str, old: str, new: str, count: int | None = None) -> str) | ((eval_ctx: EvalContext, value: str, trim_url_limit: int | None = None, nofollow: bool = False, target: str | None = None, rel: str | None = None, extra_schemes: Iterable[str] | None = None) -> str) | ((eval_ctx: EvalContext, value: Any, indent: int | None = None) -> Markup) | ((s: str) -> int) | ((s: str) -> str) | ((s: str, width: int | str = 4, first: bool = False, blank: bool = False) -> str) | ((value: HasHTML | str) -> Markup) | ((value: HasHTML | str) -> str) | ((value: Iterable[tuple[str, Any]] | Mapping[str, Any] | str) -> str) | ((value: float | int | str, binary: bool = False) -> str) | ((value: float, precision: int = 0, method: Literal['ceil', 'common', 'floor'] = 'common') -> float) | ((value: str) -> Markup) | ((value: str, chars: str | None = None) -> str) | ((value: str, width: int = 80) -> str) | ((value: str, *args: Any, **kwargs: Any) -> str) | ((value: Any) -> str) | ((value: Any, default: float = ...) -> float) | ((value: Any, default: int = 0, base: int = 10) -> int) | ((*args: Unknown, **kwargs: Unknown) -> Unknown) | Overload[(context: Context, value: AsyncIterable[Any] | Iterable[Any], name: str, *args: Any, **kwargs: Any) -> Iterable[Any], (context: Context, value: AsyncIterable[Any] | Iterable[Any], *, attribute: str = ..., default: Any | None = None) -> Iterable[Any]] | Overload[(value: str) -> str, [V](value: Iterable[Unknown]) -> Iterable[Unknown]] | [K, V](value: Mapping[Unknown, Unknown], case_sensitive: bool = False, by: Literal['key', 'value'] = 'key', reverse: bool = False) -> list[tuple[Unknown, Unknown]] | [K, V](value: Mapping[Unknown, Unknown] | Undefined) -> Iterator[tuple[Unknown, Unknown]] | [V](value: Iterable[Unknown], linecount: int, fill_with: Unknown | None = None) -> Iterator[list[Unknown]] | [V](value: Unknown, default_value: Unknown = ..., boolean: bool = False) -> Unknown | [V](environment: Environment, seq: Reversible[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], case_sensitive: bool = False, attribute: int | str | None = None) -> Undefined | Unknown | [V](context: Context, seq: Sequence[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], reverse: bool = False, case_sensitive: bool = False, attribute: int | str | None = None) -> list[Unknown] | [_T](x: SupportsAbs[Unknown], /) -> Unknown]` [unsupported-operation]
+ ERROR tests/test_async.py:647:31-62: Cannot set item in `dict[str, ((obj: Sized, /) -> int) | ((s: Any, /) -> Markup) | ((s: Any, /) -> str) | ((env: Environment, s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: int | None = None) -> str) | ((environment: Environment, obj: Any, name: str) -> Undefined | Any) | ((environment: Environment, s: str, width: int = 79, break_long_words: bool = True, wrapstring: str | None = None, break_on_hyphens: bool = True) -> str) | ((eval_ctx: EvalContext, d: Mapping[str, Any], autospace: bool = True) -> str) | ((eval_ctx: EvalContext, s: str, old: str, new: str, count: int | None = None) -> str) | ((eval_ctx: EvalContext, value: str, trim_url_limit: int | None = None, nofollow: bool = False, target: str | None = None, rel: str | None = None, extra_schemes: Iterable[str] | None = None) -> str) | ((eval_ctx: EvalContext, value: Any, indent: int | None = None) -> Markup) | ((s: str) -> int) | ((s: str) -> str) | ((s: str, width: int | str = 4, first: bool = False, blank: bool = False) -> str) | ((value: HasHTML | str) -> Markup) | ((value: HasHTML | str) -> str) | ((value: Iterable[tuple[str, Any]] | Mapping[str, Any] | str) -> str) | ((value: float | int | str, binary: bool = False) -> str) | ((value: float, precision: int = 0, method: Literal['ceil', 'common', 'floor'] = 'common') -> float) | ((value: str) -> Markup) | ((value: str, chars: str | None = None) -> str) | ((value: str, width: int = 80) -> str) | ((value: str, *args: Any, **kwargs: Any) -> str) | ((value: Any) -> str) | ((value: Any, default: float = ...) -> float) | ((value: Any, default: int = 0, base: int = 10) -> int) | ((*args: Unknown, **kwargs: Unknown) -> Unknown) | Overload[(context: Context, value: AsyncIterable[Any] | Iterable[Any], name: str, *args: Any, **kwargs: Any) -> Iterable[Any], (context: Context, value: AsyncIterable[Any] | Iterable[Any], *, attribute: str = ..., default: Any | None = None) -> Iterable[Any]] | Overload[(value: str) -> str, [V](value: Iterable[Unknown]) -> Iterable[Unknown]] | [K, V](value: Mapping[Unknown, Unknown] | Undefined) -> Iterator[tuple[Unknown, Unknown]] | [K, V](value: Mapping[Unknown, Unknown], case_sensitive: bool = False, by: Literal['key', 'value'] = 'key', reverse: bool = False) -> list[tuple[Unknown, Unknown]] | [V](value: Iterable[Unknown], linecount: int, fill_with: Unknown | None = None) -> Iterator[list[Unknown]] | [V](value: Unknown, default_value: Unknown = ..., boolean: bool = False) -> Unknown | [V](environment: Environment, seq: Reversible[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], case_sensitive: bool = False, attribute: int | str | None = None) -> Undefined | Unknown | [V](context: Context, seq: Sequence[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], reverse: bool = False, case_sensitive: bool = False, attribute: int | str | None = None) -> list[Unknown] | [_T](x: SupportsAbs[Unknown], /) -> Unknown]` [unsupported-operation]
- ERROR tests/test_regression.py:87:34-66: Cannot set item in `dict[str, ((obj: Sized, /) -> int) | ((s: Any, /) -> Markup) | ((s: Any, /) -> str) | ((env: Environment, s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: int | None = None) -> str) | ((environment: Environment, obj: Any, name: str) -> Undefined | Any) | ((environment: Environment, s: str, width: int = 79, break_long_words: bool = True, wrapstring: str | None = None, break_on_hyphens: bool = True) -> str) | ((eval_ctx: EvalContext, d: Mapping[str, Any], autospace: bool = True) -> str) | ((eval_ctx: EvalContext, s: str, old: str, new: str, count: int | None = None) -> str) | ((eval_ctx: EvalContext, value: str, trim_url_limit: int | None = None, nofollow: bool = False, target: str | None = None, rel: str | None = None, extra_schemes: Iterable[str] | None = None) -> str) | ((eval_ctx: EvalContext, value: Any, indent: int | None = None) -> Markup) | ((s: str) -> int) | ((s: str) -> str) | ((s: str, width: int | str = 4, first: bool = False, blank: bool = False) -> str) | ((value: HasHTML | str) -> Markup) | ((value: HasHTML | str) -> str) | ((value: Iterable[tuple[str, Any]] | Mapping[str, Any] | str) -> str) | ((value: float | int | str, binary: bool = False) -> str) | ((value: float, precision: int = 0, method: Literal['ceil', 'common', 'floor'] = 'common') -> float) | ((value: str) -> Markup) | ((value: str, chars: str | None = None) -> str) | ((value: str, width: int = 80) -> str) | ((value: str, *args: Any, **kwargs: Any) -> str) | ((value: Any) -> str) | ((value: Any, default: float = ...) -> float) | ((value: Any, default: int = 0, base: int = 10) -> int) | ((*args: Unknown, **kwargs: Unknown) -> Unknown) | Overload[(context: Context, value: AsyncIterable[Any] | Iterable[Any], name: str, *args: Any, **kwargs: Any) -> Iterable[Any], (context: Context, value: AsyncIterable[Any] | Iterable[Any], *, attribute: str = ..., default: Any | None = None) -> Iterable[Any]] | Overload[(value: str) -> str, [V](value: Iterable[Unknown]) -> Iterable[Unknown]] | [K, V](value: Mapping[Unknown, Unknown], case_sensitive: bool = False, by: Literal['key', 'value'] = 'key', reverse: bool = False) -> list[tuple[Unknown, Unknown]] | [K, V](value: Mapping[Unknown, Unknown] | Undefined) -> Iterator[tuple[Unknown, Unknown]] | [V](value: Iterable[Unknown], linecount: int, fill_with: Unknown | None = None) -> Iterator[list[Unknown]] | [V](value: Unknown, default_value: Unknown = ..., boolean: bool = False) -> Unknown | [V](environment: Environment, seq: Reversible[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], case_sensitive: bool = False, attribute: int | str | None = None) -> Undefined | Unknown | [V](context: Context, seq: Sequence[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], reverse: bool = False, case_sensitive: bool = False, attribute: int | str | None = None) -> list[Unknown] | [_T](x: SupportsAbs[Unknown], /) -> Unknown]` [unsupported-operation]
+ ERROR tests/test_regression.py:87:34-66: Cannot set item in `dict[str, ((obj: Sized, /) -> int) | ((s: Any, /) -> Markup) | ((s: Any, /) -> str) | ((env: Environment, s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: int | None = None) -> str) | ((environment: Environment, obj: Any, name: str) -> Undefined | Any) | ((environment: Environment, s: str, width: int = 79, break_long_words: bool = True, wrapstring: str | None = None, break_on_hyphens: bool = True) -> str) | ((eval_ctx: EvalContext, d: Mapping[str, Any], autospace: bool = True) -> str) | ((eval_ctx: EvalContext, s: str, old: str, new: str, count: int | None = None) -> str) | ((eval_ctx: EvalContext, value: str, trim_url_limit: int | None = None, nofollow: bool = False, target: str | None = None, rel: str | None = None, extra_schemes: Iterable[str] | None = None) -> str) | ((eval_ctx: EvalContext, value: Any, indent: int | None = None) -> Markup) | ((s: str) -> int) | ((s: str) -> str) | ((s: str, width: int | str = 4, first: bool = False, blank: bool = False) -> str) | ((value: HasHTML | str) -> Markup) | ((value: HasHTML | str) -> str) | ((value: Iterable[tuple[str, Any]] | Mapping[str, Any] | str) -> str) | ((value: float | int | str, binary: bool = False) -> str) | ((value: float, precision: int = 0, method: Literal['ceil', 'common', 'floor'] = 'common') -> float) | ((value: str) -> Markup) | ((value: str, chars: str | None = None) -> str) | ((value: str, width: int = 80) -> str) | ((value: str, *args: Any, **kwargs: Any) -> str) | ((value: Any) -> str) | ((value: Any, default: float = ...) -> float) | ((value: Any, default: int = 0, base: int = 10) -> int) | ((*args: Unknown, **kwargs: Unknown) -> Unknown) | Overload[(context: Context, value: AsyncIterable[Any] | Iterable[Any], name: str, *args: Any, **kwargs: Any) -> Iterable[Any], (context: Context, value: AsyncIterable[Any] | Iterable[Any], *, attribute: str = ..., default: Any | None = None) -> Iterable[Any]] | Overload[(value: str) -> str, [V](value: Iterable[Unknown]) -> Iterable[Unknown]] | [K, V](value: Mapping[Unknown, Unknown] | Undefined) -> Iterator[tuple[Unknown, Unknown]] | [K, V](value: Mapping[Unknown, Unknown], case_sensitive: bool = False, by: Literal['key', 'value'] = 'key', reverse: bool = False) -> list[tuple[Unknown, Unknown]] | [V](value: Iterable[Unknown], linecount: int, fill_with: Unknown | None = None) -> Iterator[list[Unknown]] | [V](value: Unknown, default_value: Unknown = ..., boolean: bool = False) -> Unknown | [V](environment: Environment, seq: Reversible[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], case_sensitive: bool = False, attribute: int | str | None = None) -> Undefined | Unknown | [V](context: Context, seq: Sequence[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], reverse: bool = False, case_sensitive: bool = False, attribute: int | str | None = None) -> list[Unknown] | [_T](x: SupportsAbs[Unknown], /) -> Unknown]` [unsupported-operation]
- ERROR tests/test_security.py:182:30-33: Cannot set item in `dict[str, ((obj: Sized, /) -> int) | ((s: Any, /) -> Markup) | ((s: Any, /) -> str) | ((env: Environment, s: str, length: int = 255, killwords: bool = False, end: str = '...', leeway: int | None = None) -> str) | ((environment: Environment, obj: Any, name: str) -> Undefined | Any) | ((environment: Environment, s: str, width: int = 79, break_long_words: bool = True, wrapstring: str | None = None, break_on_hyphens: bool = True) -> str) | ((eval_ctx: EvalContext, d: Mapping[str, Any], autospace: bool = True) -> str) | ((eval_ctx: EvalContext, s: str, old: str, new: str, count: int | None = None) -> str) | ((eval_ctx: EvalContext, value: str, trim_url_limit: int | None = None, nofollow: bool = False, target: str | None = None, rel: str | None = None, extra_schemes: Iterable[str] | None = None) -> str) | ((eval_ctx: EvalContext, value: Any, indent: int | None = None) -> Markup) | ((s: str) -> int) | ((s: str) -> str) | ((s: str, width: int | str = 4, first: bool = False, blank: bool = False) -> str) | ((value: HasHTML | str) -> Markup) | ((value: HasHTML | str) -> str) | ((value: Iterable[tuple[str, Any]] | Mapping[str, Any] | str) -> str) | ((value: float | int | str, binary: bool = False) -> str) | ((value: float, precision: int = 0, method: Literal['ceil', 'common', 'floor'] = 'common') -> float) | ((value: str) -> Markup) | ((value: str, chars: str | None = None) -> str) | ((value: str, width: int = 80) -> str) | ((value: str, *args: Any, **kwargs: Any) -> str) | ((value: Any) -> str) | ((value: Any, default: float = ...) -> float) | ((value: Any, default: int = 0, base: int = 10) -> int) | ((*args: Unknown, **kwargs: Unknown) -> Unknown) | Overload[(context: Context, value: AsyncIterable[Any] | Iterable[Any], name: str, *args: Any, **kwargs: Any) -> Iterable[Any], (context: Context, value: AsyncIterable[Any] | Iterable[Any], *, attribute: str = ..., default: Any | None = None) -> Iterable[Any]] | Overload[(value: str) -> str, [V](value: Iterable[Unknown]) -> Iterable[Unknown]] | [K, V](value: Mapping[Unknown, Unknown], case_sensitive: bool = False, by: Literal['key', 'value'] = 'key', reverse: bool = False) -> list[tuple[Unknown, Unknown]] | [K, V](value: Mapping[Unknown, Unknown] | Undefined) -> Iterator[tuple[Unknown, Unknown]] | [V](value: Iterable[Unknown], linecount: int, fill_with: Unknown | None = None) -> Iterator[list[Unknown]] | [V](value: Unknown, default_value: Unknown = ..., boolean: bool = False) -> Unknown | [V](environment: Environment, seq: Reversible[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], case_sensitive: bool = False, attribute: int | str | None = None) -> Undefined | Unknown | [V](context: Context, seq: Sequence[Unknown]) -> Undefined | Unknown | [V](environment: Environment, value: Iterable[Unknown], reverse: bool = False, case_sensitive: bool = False, attribute: int | str | None = None) -> list[Unknown] | [_T](x: SupportsAbs[Unknown], /) -> Unknown]` [unsupported-operation]

... (truncated 9 lines) ...