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[ty] Simple syntactic validation for PEP-613 type aliases#22652

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AlexWaygood merged 3 commits intomainfrom
alex/validate-typealias
Jan 17, 2026
Merged

[ty] Simple syntactic validation for PEP-613 type aliases#22652
AlexWaygood merged 3 commits intomainfrom
alex/validate-typealias

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@AlexWaygood AlexWaygood commented Jan 17, 2026 •
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Summary

Full validation of PEP-613 type aliases is hard, but we can improve our typing conformance-suite score by quite a bit by adding some simple syntactic checks.

Test Plan

mdtests added

@AlexWaygood AlexWaygood added the ty Multi-file analysis & type inference label Jan 17, 2026
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astral-sh-bot bot commented Jan 17, 2026 •
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Typing conformance results improved 🎉

The percentage of diagnostics emitted that were expected errors increased from 70.27% to 70.65%. The percentage of expected errors that received a diagnostic increased from 60.13% to 61.24%.

Summary

Metric Old New Diff Outcome
True Positives 650 662 +12 ⏫ (✅)
False Positives 275 275 +0
False Negatives 431 419 -12 ⏬ (✅)
Total Diagnostics 925 937 +12 ⏫
Precision 70.27% 70.65% +0.38% ⏫ (✅)
Recall 60.13% 61.24% +1.11% ⏫ (✅)

True positives added

Details
Location Name Message
aliases_explicit.py:79:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:80:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:81:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:82:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:83:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:84:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:85:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:86:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:88:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:89:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:90:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment
aliases_explicit.py:91:1 invalid-type-form Invalid right-hand side for typing.TypeAlias assignment

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astral-sh-bot bot commented Jan 17, 2026 •
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mypy_primer results

Changes were detected when running on open source projects 
tornado (https://github.com/tornadoweb/tornado)
- tornado/gen.py:255:62: error[invalid-argument-type] Argument to bound method `__init__` is incorrect: Expected `None | Awaitable[Unknown] | list[Awaitable[Unknown]] | dict[Any, Awaitable[Unknown]] | Future[Unknown]`, found `_T@next | _T@next | _VT@next`
+ tornado/gen.py:255:62: error[invalid-argument-type] Argument to bound method `__init__` is incorrect: Expected `None | Awaitable[Unknown] | list[Awaitable[Unknown]] | dict[Any, Awaitable[Unknown]] | Future[Unknown]`, found `_T@next | _VT@next | _T@next`

prefect (https://github.com/PrefectHQ/prefect)
- src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `T@resolve_block_document_references | dict[str, Any] | str | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `T@resolve_block_document_references | dict[str, Any]` is not assignable to `dict[str, Any]`
- src/integrations/prefect-dbt/prefect_dbt/core/settings.py:99:28: error[invalid-assignment] Object of type `T@resolve_variables | str | int | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/integrations/prefect-dbt/prefect_dbt/core/settings.py:99:28: error[invalid-assignment] Object of type `T@resolve_variables | dict[str, Any]` is not assignable to `dict[str, Any]`
- src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `T@resolve_block_document_references | dict[str, Any] | str | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `T@resolve_block_document_references | dict[str, Any]` is not assignable to `dict[str, Any]`
- src/prefect/cli/deploy/_core.py:87:21: error[invalid-assignment] Object of type `T@resolve_variables | str | int | ... omitted 4 union elements` is not assignable to `dict[str, Any]`
+ src/prefect/cli/deploy/_core.py:87:21: error[invalid-assignment] Object of type `T@resolve_variables` is not assignable to `dict[str, Any]`
- src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | dict[str, Any] | str | ... omitted 4 union elements`
+ src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | dict[str, Any]`
- src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `T@resolve_block_document_references | dict[str, Any] | str | ... omitted 4 union elements` on object of type `dict[str, Any]`
+ src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `T@resolve_block_document_references | dict[str, Any]` on object of type `dict[str, Any]`
- src/prefect/utilities/templating.py:323:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_block_document_references | dict[str, Any]`, found `list[T@resolve_block_document_references | dict[str, Any] | str | ... omitted 5 union elements]`
+ src/prefect/utilities/templating.py:323:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_block_document_references | dict[str, Any]`, found `list[T@resolve_block_document_references | dict[str, Any] | Unknown]`
- src/prefect/utilities/templating.py:437:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `dict[object, T@resolve_variables | str | int | ... omitted 5 union elements]`
+ src/prefect/utilities/templating.py:437:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `dict[object, T@resolve_variables | Unknown]`
- src/prefect/utilities/templating.py:442:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `list[T@resolve_variables | str | int | ... omitted 5 union elements]`
+ src/prefect/utilities/templating.py:442:16: error[invalid-return-type] Return type does not match returned value: expected `T@resolve_variables`, found `list[T@resolve_variables | Unknown]`
- src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | dict[str, Any] | str | ... omitted 4 union elements`
+ src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Expected `T@resolve_variables`, found `T@resolve_block_document_references | dict[str, Any]`
- src/prefect/workers/base.py:234:20: error[invalid-argument-type] Argument expression after ** must be a mapping type: Found `T@resolve_variables | str | int | ... omitted 4 union elements`
+ src/prefect/workers/base.py:234:20: error[invalid-argument-type] Argument expression after ** must be a mapping type: Found `T@resolve_variables`

static-frame (https://github.com/static-frame/static-frame)
- static_frame/core/bus.py:675:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Bus[Any], object_]`, found `InterGetItemILocReduces[Self@iloc | Bus[Any], object_ | Self@iloc]`
+ static_frame/core/bus.py:671:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemLocReduces[Bus[Any], object_]`, found `InterGetItemLocReduces[Bus[Any] | Bottom[Index[Any]] | TypeBlocks | ... omitted 6 union elements, object_]`
+ static_frame/core/bus.py:675:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Bus[Any], object_]`, found `InterGetItemILocReduces[Bus[Any] | ndarray[Never, Never] | TypeBlocks | ... omitted 6 union elements, object_ | Self@iloc]`
- static_frame/core/node_selector.py:526:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemLocReduces[TVContainer_co@InterfaceSelectQuartet, Any]`, found `InterGetItemLocReduces[Bottom[Series[Any, Any]] | Unknown, Any]`
+ static_frame/core/node_selector.py:526:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemLocReduces[TVContainer_co@InterfaceSelectQuartet, Any]`, found `InterGetItemLocReduces[Unknown | Bottom[Series[Any, Any]], Any]`
- static_frame/core/series.py:772:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Series[Any, Any], TVDtype@Series]`, found `InterGetItemILocReduces[Series[Any, Any] | Bottom[Index[Any]] | TypeBlocks | ... omitted 6 union elements, TVDtype@Series]`
+ static_frame/core/yarn.py:418:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[Yarn[Any], object_]`, found `InterGetItemILocReduces[Yarn[Any] | Bottom[Index[Any]] | TypeBlocks | ... omitted 6 union elements, object_]`
- Found 1823 diagnostics
+ Found 1824 diagnostics

rotki (https://github.com/rotki/rotki)
+ rotkehlchen/chain/decoding/tools.py:96:44: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- rotkehlchen/chain/decoding/tools.py:97:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `BTCAddress | ChecksumAddress | SubstrateAddress | SolanaAddress`, found `A@BaseDecoderTools`
+ rotkehlchen/chain/decoding/tools.py:99:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `Sequence[A@BaseDecoderTools]`, found `Unknown | tuple[BTCAddress, ...] | tuple[ChecksumAddress, ...] | tuple[SubstrateAddress, ...] | tuple[SolanaAddress, ...]`
- rotkehlchen/chain/decoding/tools.py:98:13: error[invalid-argument-type] Argument to function `decode_transfer_direction` is incorrect: Expected `BTCAddress | ChecksumAddress | SubstrateAddress | SolanaAddress | None`, found `A@BaseDecoderTools | None`
+ rotkehlchen/chain/decoding/tools.py:100:62: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- Found 2056 diagnostics
+ Found 2057 diagnostics

core (https://github.com/home-assistant/core)
+ homeassistant/util/variance.py:47:12: error[invalid-return-type] Return type does not match returned value: expected `(**_P@ignore_variance) -> _R@ignore_variance`, found `_Wrapped[_P@ignore_variance, _R@ignore_variance | int | float | datetime, _P@ignore_variance, _R@ignore_variance | int | float | datetime]`
- Found 14496 diagnostics
+ Found 14497 diagnostics

No memory usage changes detected ✅

@AlexWaygood AlexWaygood force-pushed the alex/validate-typealias branch from 38ff232 to 251b9e8 Compare January 17, 2026 14:23
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astral-sh-bot bot commented Jan 17, 2026 •
edited
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ecosystem-analyzer results

Lint rule Added Removed Changed
invalid-return-type 0 1 7
invalid-assignment 0 0 5
invalid-argument-type 0 0 3
Total 0 1 15

Full report with detailed diff (timing results)

@AlexWaygood AlexWaygood force-pushed the alex/validate-typealias branch 4 times, most recently from 2ff4232 to 0f39a51 Compare January 17, 2026 14:47
@AlexWaygood AlexWaygood force-pushed the alex/validate-typealias branch from 0f39a51 to 53b4349 Compare January 17, 2026 14:49
@AlexWaygood AlexWaygood marked this pull request as ready for review January 17, 2026 14:55
charliermarsh
charliermarsh reviewed Jan 17, 2026
View reviewed changes
@AlexWaygood AlexWaygood force-pushed the alex/validate-typealias branch from 5928549 to 7fe8f41 Compare January 17, 2026 15:32
@AlexWaygood AlexWaygood force-pushed the alex/validate-typealias branch from 7fe8f41 to 12401e2 Compare January 17, 2026 15:33
@AlexWaygood AlexWaygood enabled auto-merge (squash) January 17, 2026 15:41
@AlexWaygood AlexWaygood merged commit 6b16931 into main Jan 17, 2026
48 checks passed
@AlexWaygood AlexWaygood deleted the alex/validate-typealias branch January 17, 2026 15:43
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@charliermarsh charliermarsh charliermarsh approved these changes

@carljm carljm Awaiting requested review from carljm carljm is a code owner

@sharkdp sharkdp Awaiting requested review from sharkdp sharkdp is a code owner

@dcreager dcreager Awaiting requested review from dcreager dcreager is a code owner

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@AlexWaygood @charliermarsh