Fix type context for cast()

[hauntsaninja]

No description provided.

[JelleZijlstra]

I think this is right, let's see if mypy-primer agrees.

[hauntsaninja]

Unit tests agree, both new and old!

[JelleZijlstra]

(#12612 for context)

[github-actions]

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

cwltool (https://github.com/common-workflow-language/cwltool)
+ cwltool/provenance.py: note: In member "add_data_file" of class "ResearchObject":
+ cwltool/provenance.py:828:47: error: Redundant cast to "Aggregate"  [redundant-cast]
+ cwltool/pathmapper.py: note: In member "visit" of class "PathMapper":
+ cwltool/pathmapper.py:116:62: error: Argument 2 to "get" of "Mapping" has incompatible type "List[<nothing>]"; expected "Union[str, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], None, List[MutableMapping[str, Union[bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], None]]]]"  [arg-type]
+ cwltool/pathmapper.py:116:62: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ cwltool/pathmapper.py:116:62: note: Consider using "Sequence" instead, which is covariant
+ cwltool/pathmapper.py:158:69: error: Argument 2 to "get" of "Mapping" has incompatible type "List[<nothing>]"; expected "Union[str, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], None, List[MutableMapping[str, Union[bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], None]]]]"  [arg-type]
+ cwltool/pathmapper.py:158:69: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ cwltool/pathmapper.py:158:69: note: Consider using "Sequence" instead, which is covariant
+ cwltool/expression.py: note: In function "do_eval":
+ cwltool/expression.py:389:71: error: Argument 2 to "get" of "Mapping" has incompatible type "List[<nothing>]"; expected "Union[str, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]], MutableMapping[str, Union[None, bool, str, int, float, MutableSequence[Any], MutableMapping[str, Any]]]]], None, List[str]]"  [arg-type]
+ cwltool/expression.py:389:71: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
+ cwltool/expression.py:389:71: note: Consider using "Sequence" instead, which is covariant
+ cwltool/builder.py: note: In member "generate_arg" of class "Builder":
+ cwltool/builder.py:683:24: error: Redundant cast to "List[str]"  [redundant-cast]
+ tests/test_pack.py:134:135: note: (Skipping most remaining errors due to unresolved imports or missing stubs; fix these first)
- tests/test_pack.py:134:2: error: Untyped decorator makes function "test_pack_missing_cwlVersion" untyped  [misc]
- tests/test_pack.py:206:2: error: Untyped decorator makes function "test_packed_workflow_execution" untyped  [misc]
- tests/test_pack.py:207:2: error: Untyped decorator makes function "test_packed_workflow_execution" untyped  [misc]
- tests/test_override.py:77:2: error: Untyped decorator makes function "test_overrides" untyped  [misc]
- tests/test_override.py:78:2: error: Untyped decorator makes function "test_overrides" untyped  [misc]
- tests/test_override.py:124:2: error: Untyped decorator makes function "test_overrides_fails" untyped  [misc]
- tests/test_override.py:125:2: error: Untyped decorator makes function "test_overrides_fails" untyped  [misc]
- tests/test_mpi.py:42:2: error: Untyped decorator makes function "fake_mpi_conf" untyped  [misc]
- tests/test_mpi.py:283:2: error: Untyped decorator makes function "schema_ext11" untyped  [misc]
- tests/test_js_sandbox.py:29:2: error: Untyped decorator makes function "test_node_version" untyped  [misc]
- tests/test_js_sandbox.py:68:2: error: Untyped decorator makes function "test_value_from_two_concatenated_expressions_podman" untyped  [misc]
- tests/test_js_sandbox.py:87:88: note: (Skipping most remaining errors due to unresolved imports or missing stubs; fix these first)

kopf (https://github.com/nolar/kopf)
+ kopf/_core/engines/posting.py:98: error: Argument 1 to "walk" has incompatible type "Union[Body, Iterable[Body]]"; expected "Iterable[Iterable[<nothing>]]"
+ kopf/_core/engines/posting.py:111: error: Argument 1 to "walk" has incompatible type "Union[Body, Iterable[Body]]"; expected "Iterable[Iterable[<nothing>]]"
+ kopf/_core/engines/posting.py:124: error: Argument 1 to "walk" has incompatible type "Union[Body, Iterable[Body]]"; expected "Iterable[Iterable[<nothing>]]"
+ kopf/_core/engines/posting.py:142: error: Argument 1 to "walk" has incompatible type "Union[Body, Iterable[Body]]"; expected "Iterable[Iterable[<nothing>]]"

core (https://github.com/home-assistant/core)
+ homeassistant/loader.py:266: error: Redundant cast to "DHCPMatcher"  [redundant-cast]
+ homeassistant/loader.py:266: error: Expected TypedDict key to be string literal  [misc]
+ homeassistant/components/nanoleaf/config_flow.py:133: error: Redundant cast to "Dict[Any, Any]"  [redundant-cast]
+ homeassistant/components/nanoleaf/config_flow.py:136: error: Argument 1 to "async_add_executor_job" of "HomeAssistant" has incompatible type "Callable[[str, Union[List[Any], Dict[Any, Any], None]], Union[List[Any], Dict[Any, Any]]]"; expected "Callable[..., Dict[Any, Any]]"  [arg-type]
+ homeassistant/components/group/light.py:301: error: Redundant cast to "Set[str]"  [redundant-cast]

[hauntsaninja]

:-( There's at least some issue involving typeddicts that's genuine. Not immediately obvious to me how to fix. I don't think this is particularly important and it's very annoying for mypy to get things wrong here (since cast is a "please shut up")

[JelleZijlstra]

Which one was that? In kopf it looked like it found a real issue that was previously hidden by the Any type context.