[red-knot] Synthesize a __call__ attribute for Callable types

[AlexWaygood]

Summary

Currently this assertion fails on main, because we do not synthesize a __call__ attribute for Callable types:

from typing import Protocol, Callable
from knot_extensions import static_assert, is_assignable_to

class Foo(Protocol):
    def __call__(self, x: int, /) -> str: ...

static_assert(is_assignable_to(Callable[[int], str], Foo))

This PR fixes that.

See previous discussion about this in #16493 (comment) and #17682 (comment)

Test Plan

Existing mdtests updated; a couple of new ones added.

[github-actions]

mypy_primer results

Changes were detected when running on open source projects

jinja (https://github.com/pallets/jinja)
- error[lint:unresolved-attribute] src/jinja2/runtime.py:280:35: Type `(...) -> Any` has no attribute `__call__`
- error[lint:unresolved-attribute] src/jinja2/runtime.py:282:21: Type `(...) -> Any` has no attribute `__call__`
- Found 396 diagnostics
+ Found 394 diagnostics

poetry (https://github.com/python-poetry/poetry)
- error[lint:invalid-return-type] tests/conftest.py:697:12: Return type does not match returned value: Expected `SetProjectContext`, found `(...) -> Unknown`
- Found 1153 diagnostics
+ Found 1152 diagnostics

scrapy (https://github.com/scrapy/scrapy)
- error[lint:unresolved-attribute] scrapy/utils/python.py:269:39: Type `(...) -> Any` has no attribute `__call__`
- Found 1711 diagnostics
+ Found 1710 diagnostics

meson (https://github.com/mesonbuild/meson)
- error[lint:invalid-argument-type] mesonbuild/rewriter.py:36:91: Argument to this function is incorrect: Expected `_FormatterClass`, found `(str, /) -> HelpFormatter`
- error[lint:invalid-argument-type] mesonbuild/rewriter.py:46:82: Argument to this function is incorrect: Expected `_FormatterClass`, found `(str, /) -> HelpFormatter`
- error[lint:invalid-argument-type] mesonbuild/rewriter.py:55:119: Argument to this function is incorrect: Expected `_FormatterClass`, found `(str, /) -> HelpFormatter`
- error[lint:invalid-argument-type] mesonbuild/rewriter.py:61:109: Argument to this function is incorrect: Expected `_FormatterClass`, found `(str, /) -> HelpFormatter`
- Found 1812 diagnostics
+ Found 1808 diagnostics

bokeh (https://github.com/bokeh/bokeh)
- error[lint:invalid-argument-type] src/bokeh/resources.py:603:19: Argument to this function is incorrect: Expected `UrlsFn`, found `(components, kind) -> Unknown`
- error[lint:invalid-assignment] src/bokeh/resources.py:617:9: Object of type `(components, kind) -> Unknown` is not assignable to attribute `hashes` of type `HashesFn | None`
- error[lint:invalid-argument-type] src/bokeh/resources.py:637:17: Argument to this function is incorrect: Expected `UrlsFn`, found `(components, kind) -> Unknown`
- Found 1927 diagnostics
+ Found 1924 diagnostics

jax (https://github.com/google/jax)
- error[lint:invalid-argument-type] jax/_src/ad_checkpoint.py:816:32: Argument to this function is incorrect: Expected `LoweringRule`, found `(ctx, x, *, name) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/cudnn/fused_attention_stablehlo.py:1086:25: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/cudnn/fused_attention_stablehlo.py:1093:25: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/cudnn/fused_attention_stablehlo.py:1673:25: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/cudnn/fused_attention_stablehlo.py:1680:25: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/cudnn/scaled_matmul_stablehlo.py:304:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_batching.py:355:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_dce.py:442:19: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_derivatives.py:952:49: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_derivatives.py:1497:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_derivatives.py:1805:37: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/custom_transpose.py:243:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/error_check.py:272:5: Argument to this function is incorrect: Expected `_SerializeAuxData`, found `(x) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/error_check.py:275:5: Argument to this function is incorrect: Expected `_DeserializeAuxData`, found `(x) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/export/_export.py:504:5: Argument to this function is incorrect: Expected `_DeserializeAuxData`, found `(b) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/interpreters/mlir.py:2559:44: Argument to this function is incorrect: Expected `LoweringRule`, found `(ctx, x) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/interpreters/mlir.py:3058:33: Argument to this function is incorrect: Expected `LoweringRule`, found `(ctx, *x, *, axes, axis_index_groups) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/control_flow/for_loop.py:278:31: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/control_flow/loops.py:1392:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/control_flow/solves.py:493:21: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:4193:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:4351:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:4970:37: Argument to this function is incorrect: Expected `LoweringRule`, found `(_, x, **__) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:5005:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(_, x, **__) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:6309:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:8457:32: Argument to this function is incorrect: Expected `LoweringRule`, found `(ctx, x) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/lax.py:8875:31: Argument to this function is incorrect: Expected `LoweringRule`, found `(ctx, x, y) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:907:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:1260:13: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:1550:30: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:1690:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:1883:30: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:2304:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/linalg.py:2668:45: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/special.py:661:3: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/special.py:682:34: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/special.py:687:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/special.py:694:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/special.py:704:24: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/windowed_reductions.py:817:50: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/windowed_reductions.py:821:50: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/windowed_reductions.py:825:50: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/lax/windowed_reductions.py:1066:49: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/pallas/fuser/fusible.py:80:35: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/pallas/primitives.py:345:42: Argument to this function is incorrect: Expected `LoweringRule`, found `(_, x, **__) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/pallas/primitives.py:359:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(_, x, **__) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/prng.py:960:21: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/random.py:1302:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/random.py:1305:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/random.py:2738:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(_, k) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/state/discharge.py:607:37: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/_src/state/primitives.py:763:21: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/key_reuse/_core.py:243:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/key_reuse/_core.py:256:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/api.py:114:35: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:233:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:362:42: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:495:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:599:42: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:923:44: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:928:27: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:931:27: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:1085:5: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:1293:46: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:1378:45: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcoo.py:1564:47: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcsr.py:303:42: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcsr.py:380:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcsr.py:454:40: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/bcsr.py:790:25: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/coo.py:258:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/coo.py:371:41: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/coo.py:495:38: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/coo.py:615:38: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/csr.py:281:39: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/csr.py:401:41: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/csr.py:507:38: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/csr.py:614:38: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- error[lint:invalid-argument-type] jax/experimental/sparse/nm.py:243:35: Argument to this function is incorrect: Expected `LoweringRule`, found `(...) -> Unknown`
- Found 5566 diagnostics
+ Found 5487 diagnostics

zulip (https://github.com/zulip/zulip)
- error[lint:invalid-argument-type] zerver/tests/test_decorators.py:128:25: Argument to this function is incorrect: Expected `_GetResponseCallable`, found `(request) -> Unknown`
- error[lint:invalid-argument-type] zerver/tests/test_decorators.py:1609:25: Argument to this function is incorrect: Expected `_GetResponseCallable`, found `(request) -> Unknown`
- error[lint:invalid-argument-type] zerver/tests/test_middleware.py:247:25: Argument to this function is incorrect: Expected `_GetResponseCallable`, found `(_) -> Unknown`
- error[lint:invalid-argument-type] zerver/tests/test_middleware.py:256:25: Argument to this function is incorrect: Expected `_GetResponseCallable`, found `(_) -> Unknown`
- error[lint:invalid-argument-type] zerver/tests/test_middleware.py:265:25: Argument to this function is incorrect: Expected `_GetResponseCallable`, found `(_) -> Unknown`
- Found 5926 diagnostics
+ Found 5921 diagnostics

[AlexWaygood]

Primer results all look as expected! Here's what the jax hits look like: LoweringRule is a callback protocol defined here:

• https://github.com/jax-ml/jax/blob/43b784c3c7b961134bbdb2fdaa56a168540926cc/jax/_src/interpreters/mlir.py#L838-L843
• The register_lowering function has a parameter annotated as accepting an instance of LoweringRule here: https://github.com/jax-ml/jax/blob/43b784c3c7b961134bbdb2fdaa56a168540926cc/jax/_src/interpreters/mlir.py#L851-L852
• And jax usually passes lambda functions into that parameter at callsites. We currently just infer a plain Callable type for lambdas, so we previously complained about that, but we now understand that the lambda has a type consistent with the callback protocol: https://github.com/jax-ml/jax/blob/43b784c3c7b961134bbdb2fdaa56a168540926cc/jax/_src/ad_checkpoint.py#L816