[ty] Add diagnostic hint on unresolved-reference to suggest using "list" instead of "List"

[MentalMegalodon]

Summary

Closes astral-sh/ty#1665 .

This PR adds an info message to the diagnostic for unresolved-reference in Python 3.9+ when the reference is one of the capitalized type hints that are in the typing module, such as typing.List, pointing the user to the new lowercase instances instead. Example:

foo: List[int]
# error[unresolved-reference]: Name `List` used when not defined
#  --> /home/mark/code/temp/temp.py:1:6
#   |
# 1 | foo: List[int]
#   |      ^^^^
#   |
# info: Rename `List` to `list`.
# info: Python 3.14 was assumed when resolving types because it is the newest Python version supported by ty, and neither a command-line argument nor a configuration setting was provided
# info: rule `unresolved-reference` is enabled by default

Test Plan

Added a pair of new testcases, one which tests that the full info message shows up in the snapshot for Python 3.9, and another with the same code that checks that the info message does not show up in the snapshot for Python 3.8.

[astral-sh-bot]

Typing conformance results

No changes detected ✅

[astral-sh-bot]

mypy_primer results

Changes were detected when running on open source projects

prefect (https://github.com/PrefectHQ/prefect)
+ src/integrations/prefect-dbt/prefect_dbt/core/settings.py:94:28: error[invalid-assignment] Object of type `dict[Any, Any] | int | dict[str, Any] | ... 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 `int | dict[Any, Any] | float | ... omitted 3 union elements` is not assignable to `dict[str, Any]`
+ src/prefect/cli/deploy/_core.py:86:21: error[invalid-assignment] Object of type `dict[Any, Any] | int | dict[str, Any] | ... 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 `int | dict[Any, Any] | float | ... omitted 3 union elements` is not assignable to `dict[str, Any]`
+ src/prefect/deployments/steps/core.py:137:38: error[invalid-argument-type] Argument is incorrect: Argument type `dict[Any, Any] | int | dict[str, Any] | ... omitted 4 union elements` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
- src/prefect/utilities/templating.py:320:13: error[invalid-assignment] Invalid subscript assignment with key of type `object` and value of type `Unknown | dict[str, Any]` 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 `Unknown | int | dict[str, Any] | ... omitted 4 union elements` 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[Unknown | 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[Unknown | int | dict[str, Any] | ... omitted 4 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, 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, Unknown | int | float | ... omitted 4 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[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[Unknown | int | float | ... omitted 4 union elements]`
- src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Argument type `str | dict[str, Any]` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
+ src/prefect/workers/base.py:232:13: error[invalid-argument-type] Argument is incorrect: Argument type `str | int | dict[str, Any] | ... omitted 3 union elements` does not satisfy constraints (`str`, `int`, `int | float`, `bool`, `dict[Any, Any]`, `list[Any]`, `None`) of type variable `T`
+ src/prefect/workers/base.py:234:20: error[invalid-argument-type] Argument expression after ** must be a mapping type: Found `int | Unknown | float | ... omitted 4 union elements`
- Found 5368 diagnostics
+ Found 5374 diagnostics

pwndbg (https://github.com/pwndbg/pwndbg)
- pwndbg/aglib/disasm/riscv.py:121:35: error[unresolved-reference] Name `Dict` used when not defined
+ pwndbg/aglib/disasm/riscv.py:121:35: error[unresolved-reference] Name `Dict` used when not defined: Did you mean `dict`?
- pwndbg/aglib/kernel/__init__.py:264:20: error[unsupported-operator] Operator `+` is not supported between objects of type `Unknown | None` and `Literal[1]`
+ pwndbg/aglib/kernel/__init__.py:264:20: error[unsupported-operator] Operator `+` is not supported between objects of type `None | Unknown` and `Literal[1]`
- pwndbg/aglib/kernel/__init__.py:270:22: error[unsupported-operator] Operator `+` is not supported between objects of type `Unknown | None` and `int`
+ pwndbg/aglib/kernel/__init__.py:270:22: error[unsupported-operator] Operator `+` is not supported between objects of type `None | Unknown` and `int`

static-frame (https://github.com/static-frame/static-frame)
+ 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[Bottom[Bus[Any]] | Bottom[Series[Any, 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[Self@iloc, Self@iloc]`
+ 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[Bottom[Bus[Any]] | Bottom[Index[Any]] | Bottom[Series[Any, Any]] | ... omitted 7 union elements, Self@iloc]`
+ 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[Bottom[Series[Any, Any]] | IndexHierarchy | TypeBlocks | ... omitted 7 union elements, TVDtype@Series]`
+ static_frame/core/series.py:4072:16: error[invalid-return-type] Return type does not match returned value: expected `InterGetItemILocReduces[SeriesHE[Any, Any], TVDtype@SeriesHE]`, found `InterGetItemILocReduces[Bottom[Series[Any, Any]] | Bottom[Index[Any]] | TypeBlocks | ... omitted 7 union elements, TVDtype@SeriesHE]`
+ 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[Bottom[Yarn[Any]] | Bottom[Index[Any]] | Bottom[Series[Any, Any]] | ... omitted 7 union elements, object_]`
- Found 1819 diagnostics
+ Found 1823 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 2057 diagnostics
+ Found 2058 diagnostics

pandas-stubs (https://github.com/pandas-dev/pandas-stubs)
- tests/frame/test_groupby.py:229:15: error[type-assertion-failure] Type `Series[Any]` does not match asserted type `Series[str | bytes | int | ... omitted 12 union elements]`
- tests/frame/test_groupby.py:625:15: error[type-assertion-failure] Type `Series[Any]` does not match asserted type `Series[str | bytes | int | ... omitted 12 union elements]`
- Found 4413 diagnostics
+ Found 4411 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, int | _R@ignore_variance | float | datetime, _P@ignore_variance, _R@ignore_variance | int | float | datetime]`
- Found 14511 diagnostics
+ Found 14512 diagnostics

No memory usage changes detected ✅

[oconnor663]

LGTM overall. One comment on the info: hint.

[oconnor663]

I think extra info: like this is more useful when it's explaining behavior that doesn't happen by default / under the most recent Python version. But in this case it's a bit noisy without adding a lot of value?

[MentalMegalodon]

Understood, removed.