use is_same_type when determining if a cast is redundant

[asottile]

while working on #18540 (which my original prototype based the code on warn-redundant-casts) I noticed the suggestion here would probably make sense to apply to redundant-cast as well!

I also made sure to include the example from the original implementation just to make sure I wasn't regressing that as well since it seemed related.

[asottile]

almost all of the primer output is an improvement.

I noticed one new bug which was sort of hidden before (for instance from pandera):

from typing import TypeAlias, Any, cast

x: TypeAlias = Any
y: TypeAlias = Any
z: TypeAlias = Any


def f(q: x | y | z) -> None:
    cast(x | y, q)

the current redundant-cast code checks for Any specifically but not for equivalent "Any"s such as Any | Any

I can fix this with is_same_type(target_type, AnyType(TypeOfAny.whatever)) I believe

---

The other oddity I noticed is the one from antidote where a cast from a clearly abstract protocol to type[ThatProtocol] is written to avoid type-abstract. imo this should be an error and they should ignore type-abstract instead -- here's a minimal example:

from typing import cast, Protocol

def f[T](t: type[T]) -> None: ...

class P[T](Protocol):
    def get(self) -> T: ...

f(P[int])  # type: ignore[type-abstract]
f(cast(type[P[int]], P[int]))  # ok: becomes warn-redundant-cast

[github-actions]

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

prefect (https://github.com/PrefectHQ/prefect)
+ src/prefect/utilities/collections.py:141: error: Redundant cast to "NestedDict[Any]"  [redundant-cast]
+ src/prefect/utilities/collections.py:456: error: Redundant cast to "BaseAnnotation"  [redundant-cast]
+ src/prefect/utilities/collections.py:693: error: Redundant cast to "NestedDict[Any]"  [redundant-cast]
+ src/prefect/utilities/collections.py:720: error: Redundant cast to "Union[VT2?, NestedDict[Any]]"  [redundant-cast]
+ src/prefect/utilities/callables.py:681: error: Redundant cast to "unmapped"  [redundant-cast]

altair (https://github.com/vega/altair)
+ altair/vegalite/v5/api.py:1110: error: Redundant cast to "_Conditional[list[_ConditionClosed]]"  [redundant-cast]

cwltool (https://github.com/common-workflow-language/cwltool)
+ cwltool/update.py: note: In function "v1_0to1_1":
+ cwltool/update.py:135:56: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/secrets.py: note: In member "has_secret" of class "SecretStore":
+ cwltool/secrets.py:46:36: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/secrets.py:50:36: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/secrets.py: note: In member "retrieve" of class "SecretStore":
+ cwltool/secrets.py:61:38: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/secrets.py:63:35: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/cwlprov/ro.py: note: In member "_relativise_files" of class "ResearchObject":
+ cwltool/cwlprov/ro.py:677:44: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/cwlprov/ro.py:685:40: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/process.py: note: In function "avroize_type":
+ cwltool/process.py:447:47: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/process.py: note: In function "var_spool_cwl_detector":
+ cwltool/process.py:493:40: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/process.py:496:40: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/checker.py: note: In function "merge_flatten_type":
+ cwltool/checker.py:57:36: error: Redundant cast to "SinkType"  [redundant-cast]
+ cwltool/checker.py: note: In function "can_assign_src_to_sink":
+ cwltool/checker.py:98:13: error: Redundant cast to "SinkType"  [redundant-cast]
+ cwltool/checker.py:98:42: error: Redundant cast to "SinkType | None"  [redundant-cast]
+ cwltool/checker.py:103:47: error: Redundant cast to "SinkType"  [redundant-cast]
+ cwltool/checker.py:107:62: error: Redundant cast to "SinkType"  [redundant-cast]
+ cwltool/checker.py:112:44: error: Redundant cast to "SinkType"  [redundant-cast]
+ cwltool/pack.py: note: In function "find_ids":
+ cwltool/pack.py:50:22: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/pack.py: note: In function "import_embed":
+ cwltool/pack.py:87:26: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/pack.py:103:26: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/command_line_tool.py: note: In member "_initialworkdir" of class "CommandLineTool":
+ cwltool/command_line_tool.py:519:33: error: Redundant cast to "MutableSequence[CWLOutputType | None]"  [redundant-cast]
+ cwltool/command_line_tool.py: note: In member "collect_output" of class "CommandLineTool":
+ cwltool/command_line_tool.py:1403:38: error: Redundant cast to "CWLOutputType"  [redundant-cast]
+ cwltool/main.py: note: In function "realize_input_schema":
+ cwltool/main.py:308:43: error: Redundant cast to "CWLObjectType"  [redundant-cast]

pandas (https://github.com/pandas-dev/pandas)
+ pandas/core/internals/blocks.py:822: error: Redundant cast to "ExtensionArray | ndarray[Any, Any]"  [redundant-cast]

dd-trace-py (https://github.com/DataDog/dd-trace-py)
+ ddtrace/_trace/utils_botocore/span_pointers/dynamodb.py:488: error: Redundant cast to "_DynamoDBDeleteRequestWriteRequest"  [redundant-cast]
+ ddtrace/_trace/utils_botocore/span_pointers/dynamodb.py:559: error: Redundant cast to "_DynamoDBTransactUpdateItem"  [redundant-cast]

streamlit (https://github.com/streamlit/streamlit)
+ lib/streamlit/elements/lib/color_util.py: note: In function "_normalize_tuple":
+ lib/streamlit/elements/lib/color_util.py:229:24: error: Redundant cast to "Union[Tuple[float, float, float, float], Tuple[int, int, int, int], Tuple[int, int, int, float]]"  [redundant-cast]
+ lib/streamlit/elements/vega_charts.py: note: In member "_vega_lite_chart" of class "VegaChartsMixin":
+ lib/streamlit/elements/vega_charts.py:1971:20: error: Redundant cast to "VegaLiteState"  [redundant-cast]
+ lib/streamlit/elements/plotly_chart.py: note: In function "plotly_chart":
+ lib/streamlit/elements/plotly_chart.py:540:20: error: Redundant cast to "PlotlyState"  [redundant-cast]
+ lib/streamlit/elements/deck_gl_json_chart.py: note: In function "pydeck_chart":
+ lib/streamlit/elements/deck_gl_json_chart.py:522:20: error: Redundant cast to "PydeckState"  [redundant-cast]
+ lib/streamlit/elements/arrow.py: note: In function "dataframe":
+ lib/streamlit/elements/arrow.py:628:20: error: Redundant cast to "DataframeState"  [redundant-cast]
+ lib/streamlit/elements/widgets/time_widgets.py: note: In member "_date_input" of class "TimeWidgetsMixin":
+ lib/streamlit/elements/widgets/time_widgets.py:866:49: error: Redundant cast to "Union[date, datetime, str, Literal['today'], None]"  [redundant-cast]

pylint (https://github.com/pycqa/pylint)
+ pylint/lint/report_functions.py:59: error: Redundant cast to "Literal['convention', 'error', 'fatal', 'info', 'refactor', 'statement', 'warning']"  [redundant-cast]
+ pylint/checkers/raw_metrics.py:28: error: Redundant cast to "Literal['code', 'docstring', 'comment', 'empty']"  [redundant-cast]
+ pylint/checkers/base/basic_checker.py:73: error: Redundant cast to "Literal['function', 'class', 'method', 'module']"  [redundant-cast]

spark (https://github.com/apache/spark)
+ python/pyspark/profiler.py:332: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]
+ python/pyspark/profiler.py:333: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]
+ python/pyspark/profiler.py:334: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]
+ python/pyspark/profiler.py:335: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]
+ python/pyspark/profiler.py:338: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]
+ python/pyspark/profiler.py:340: error: Redundant cast to "tuple[float, float, int]"  [redundant-cast]

openlibrary (https://github.com/internetarchive/openlibrary)
+ openlibrary/core/lists/model.py: note: In member "from_json" of class "Seed":
+ openlibrary/core/lists/model.py:458: error: Redundant cast to "ThingReferenceDict"  [redundant-cast]
+ openlibrary/plugins/openlibrary/lists.py: note: In member "normalize_input_seed" of class "ListRecord":
+ openlibrary/plugins/openlibrary/lists.py:91: error: Redundant cast to "ThingReferenceDict"  [redundant-cast]
+ openlibrary/plugins/openlibrary/lists.py: note: At top level:

scrapy (https://github.com/scrapy/scrapy)
+ scrapy/http/request/form.py:110: error: Redundant cast to "Iterable[str]"  [redundant-cast]

sockeye (https://github.com/awslabs/sockeye)
+ sockeye/data_io.py:1364: error: Redundant cast to "Iterator[Any]"  [redundant-cast]
+ sockeye/data_io.py:1365: error: Redundant cast to "Iterator[Any]"  [redundant-cast]

steam.py (https://github.com/Gobot1234/steam.py)
+ steam/ext/commands/help.py:35: error: Redundant cast to "CommandKwargs[Any]"  [redundant-cast]

jax (https://github.com/google/jax)
+ jax/_src/lax/lax.py:665: error: Redundant cast to "str | type[Any] | dtype[Any] | SupportsDType | None"  [redundant-cast]

core (https://github.com/home-assistant/core)
+ homeassistant/components/mealie/services.py:131: error: Redundant cast to "ConfigEntry[MealieData]"  [redundant-cast]
+ homeassistant/components/command_line/switch.py:43: error: Redundant cast to "dict[str, Any]"  [redundant-cast]
+ homeassistant/components/command_line/sensor.py:54: error: Redundant cast to "dict[str, Any]"  [redundant-cast]
+ homeassistant/components/command_line/notify.py:29: error: Redundant cast to "dict[str, Any]"  [redundant-cast]
+ homeassistant/components/command_line/cover.py:44: error: Redundant cast to "dict[str, Any]"  [redundant-cast]
+ homeassistant/components/nws/weather.py:181: error: Redundant cast to "Literal['twice_daily', 'hourly']"  [redundant-cast]
+ homeassistant/components/command_line/binary_sensor.py:46: error: Redundant cast to "dict[str, Any]"  [redundant-cast]

kornia (https://github.com/kornia/kornia)
+ kornia/contrib/extract_patches.py:118: error: Redundant cast to "tuple[int, int, int, int]"  [redundant-cast]
+ kornia/contrib/extract_patches.py:384: error: Redundant cast to "tuple[int, int, int, int]"  [redundant-cast]

pyinstrument (https://github.com/joerick/pyinstrument)
- pyinstrument/renderers/jsonrenderer.py:17: error: Unused "type: ignore" comment  [unused-ignore]

antidote (https://github.com/Finistere/antidote)
+ tests/lib/interface/test_custom.py:300: error: Redundant cast to "type[EventSubscriber[InitializationEvent]]"  [redundant-cast]

dedupe (https://github.com/dedupeio/dedupe)
+ dedupe/api.py:1547: error: Redundant cast to "Literal['match', 'distinct']"  [redundant-cast]

[sterliakov]

Also fixes #12328?

[hauntsaninja]

Great, thank you!