[ty] Infer types for names bound in match patterns

[charliermarsh]

Summary

This PR teaches ty to infer types for names introduced by match patterns.

def f(x: object) -> None:
    match x:
        case [int() as item, _]:
            reveal_type(item)  # revealed: int

Previously, these bindings used a placeholder type. Rather than adding a separate inference path for every pattern form, we extend the existing match-pattern model to describe the names produced by a successful match. The same analysis that determines which values can reach a case now determines what each name refers to.

This covers captures, as patterns, starred sequence captures, and or alternatives. Because binding inference and match narrowing share one model, the resulting types stay consistent across nested patterns, case ordering, unions, generics, and type aliases. The inferred types are also available to hover, go-to-type, and inlay hints.

[astral-sh-bot]

Typing conformance results

No changes detected ✅

Current numbers

The percentage of diagnostics emitted that were expected errors held steady at 94.36%. The percentage of expected errors that received a diagnostic held steady at 88.82%. The number of fully passing files held steady at 93/134.

[astral-sh-bot]

Memory usage report

Memory usage unchanged ✅

[astral-sh-bot]

ecosystem-analyzer results

Lint rule	Added	Removed	Changed
invalid-argument-type	11	0	0
type-assertion-failure	0	0	4
invalid-return-type	1	0	0
Total	12	0	4

Raw diff (16 changes)

cwltool (https://github.com/common-workflow-language/cwltool)
+ cwltool/secrets.py:46:40 error[invalid-argument-type] Argument to bound method `SecretStore.has_secret` is incorrect: Expected `int | str | float | ... omitted 4 union elements`, found `object`
+ cwltool/secrets.py:50:40 error[invalid-argument-type] Argument to bound method `SecretStore.has_secret` is incorrect: Expected `int | str | float | ... omitted 4 union elements`, found `object`
+ cwltool/secrets.py:62:24 error[invalid-return-type] Return type does not match returned value: expected `int | str | float | ... omitted 4 union elements`, found `dict[object, int | str | float | ... omitted 4 union elements]`
+ cwltool/secrets.py:62:42 error[invalid-argument-type] Argument to bound method `SecretStore.retrieve` is incorrect: Expected `int | str | float | ... omitted 4 union elements`, found `object`
+ cwltool/secrets.py:64:39 error[invalid-argument-type] Argument to bound method `SecretStore.retrieve` is incorrect: Expected `int | str | float | ... omitted 4 union elements`, found `object`
+ cwltool/process.py:507:44 error[invalid-argument-type] Argument to function `var_spool_cwl_detector` is incorrect: Expected `int | str | float | ... omitted 5 union elements`, found `object`
+ cwltool/process.py:510:44 error[invalid-argument-type] Argument to function `var_spool_cwl_detector` is incorrect: Expected `int | str | float | ... omitted 5 union elements`, found `object`

jax (https://github.com/google/jax)
+ jax/_src/pallas/mosaic_gpu/lowering.py:1630:55 error[invalid-argument-type] Argument to bound method `UnswizzleRef.commute_reshape` is incorrect: Expected `ShapedArray`, found `AbstractValue`
- jax/experimental/mosaic/gpu/constraints.py:1019:7 error[type-assertion-failure] Type `@Todo` is not equivalent to `Never`
+ jax/experimental/mosaic/gpu/constraints.py:1019:7 error[type-assertion-failure] Type `(Equals & ~AlwaysTrue) | (Relayout & ~AlwaysTrue) | (NotOfType & ~AlwaysTrue) | ... omitted 5 union elements` is not equivalent to `Never`
- jax/experimental/mosaic/gpu/constraints.py:1057:11 error[type-assertion-failure] Type `@Todo` is not equivalent to `Never`
+ jax/experimental/mosaic/gpu/constraints.py:1057:11 error[type-assertion-failure] Type `(Reduce & ~Variable & ~RegisterLayout & ~SMEMTransforms & ~TMEMLayout) | (Reshape & ~Variable & ~RegisterLayout & ~SMEMTransforms & ~TMEMLayout) | (Transpose & ~Variable & ~RegisterLayout & ~SMEMTransforms & ~TMEMLayout) | (CollapseShape & ~Variable & ~RegisterLayout & ~SMEMTransforms & ~TMEMLayout)` is not equivalent to `Never`
- jax/experimental/mosaic/gpu/constraints.py:1083:11 error[type-assertion-failure] Type `@Todo` is not equivalent to `Never`
+ jax/experimental/mosaic/gpu/constraints.py:1083:11 error[type-assertion-failure] Type `(Equals & ~AlwaysTrue) | (Relayout & ~AlwaysTrue) | (NotOfType & ~AlwaysTrue) | ... omitted 5 union elements` is not equivalent to `Never`

mitmproxy (https://github.com/mitmproxy/mitmproxy)
- test/mitmproxy/addons/test_dns_resolver.py:155:17 error[type-assertion-failure] Type `@Todo` is not equivalent to `Never`
+ test/mitmproxy/addons/test_dns_resolver.py:155:17 error[type-assertion-failure] Type `tuple[Literal["nxdomain.example.com", "no-a-records.example.com", "no-network.example.com", "txt.example.com", "ipv4.example.com", "ipv6.example.com"], Literal["nameservers", "no-nameservers"], Literal["hosts", "no-hosts"]] & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'> & ~<Protocol with members '__getitem__', '__len__'>` is not equivalent to `Never`

schema_salad (https://github.com/common-workflow-language/schema_salad)
+ src/schema_salad/dotnet_codegen.py:509:45 error[invalid-argument-type] Argument to function `DotNetCodeGen.safe_name` is incorrect: Expected `str`, found `(dict[str, Any] & ~Top[MutableSequence[Unknown]]) | (str & ~Top[MutableSequence[Unknown]])`
+ src/schema_salad/java_codegen.py:571:45 error[invalid-argument-type] Argument to function `JavaCodeGen.safe_name` is incorrect: Expected `str`, found `(dict[str, Any] & ~Top[MutableSequence[Unknown]]) | (str & ~Top[MutableSequence[Unknown]])`
+ src/schema_salad/python_codegen.py:490:40 error[invalid-argument-type] Argument to function `PythonCodeGen.safe_name` is incorrect: Expected `str`, found `(dict[str, Any] & ~Top[MutableSequence[Unknown]]) | (str & ~Top[MutableSequence[Unknown]])`
+ src/schema_salad/typescript_codegen.py:444:40 error[invalid-argument-type] Argument to function `TypeScriptCodeGen.safe_name` is incorrect: Expected `str`, found `(dict[str, Any] & ~Top[MutableSequence[Unknown]]) | (str & ~Top[MutableSequence[Unknown]])`

Full report with detailed diff (timing results)

[charliermarsh]

Superseded by #25940 after the branch stack was reordered. GitHub marked this PR as merged when its former base became a descendant of this branch.