[functools] Use ParamSpec for single dispatch

[srittau]

No description provided.

[srittau]

This is some weird interaction where CI was using the main branch for some tests.

---

I'm really stumped about the mypy and pyright errors:

stubs/aiofiles/aiofiles/threadpool/__init__.pyi:102: error: "_SingleDispatchCallable" expects 2 type arguments, but 1 given  [type-arg]

/home/runner/work/typeshed/typeshed/stubs/aiofiles/aiofiles/threadpool/__init__.pyi
  /home/runner/work/typeshed/typeshed/stubs/aiofiles/aiofiles/threadpool/__init__.pyi:102:31 - error: Too few type arguments provided for "_SingleDispatchCallable"; expected 2 but received 1 (reportInvalidTypeArguments)

This looks to be the same error, but the aiofiles stubs have no relation to functools and the line in question doesn't either:

stdin: AsyncTextIndirectIOWrapper
stdout: AsyncTextIndirectIOWrapper  # it errors here and only here
stderr: AsyncTextIndirectIOWrapper
stdin_bytes: AsyncIndirectBufferedIOBase
stdout_bytes: AsyncIndirectBufferedIOBase
stderr_bytes: AsyncIndirectBufferedIOBase

# type: ignore is also ineffective and _SingleDispatchCallable is only ever used in functools (apart from a different one in stubs/singledispatch).

[github-actions]

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

dd-trace-py (https://github.com/DataDog/dd-trace-py)
+ ddtrace/internal/symbol_db/symbols.py:171: error: Argument 1 to "singledispatchmethod" has incompatible type "Callable[[type[Scope], Any, ScopeData], Scope | None]"; expected "Callable[[object, Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:171: note: This is likely because "_get_from of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:182: error: Argument 1 has incompatible type "Callable[[type[Scope], Module, ScopeData], Scope | None]"; expected "Callable[[Module, Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:182: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:184: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:204: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:235: error: Argument 1 has incompatible type "def _(cls: type[Scope], obj: type, data: ScopeData) -> Scope | None"; expected "def (type, /, _: Any, data: ScopeData) -> Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:235: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:271: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:325: error: Argument 1 has incompatible type "Callable[[type[Scope], CodeType, ScopeData], Scope | None]"; expected "Callable[[CodeType, Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:325: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:327: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:354: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:354: error: Argument 1 has incompatible type "CodeType"; expected "Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:358: error: Argument 1 has incompatible type "Callable[[type[Scope], FunctionType, ScopeData], Scope | None]"; expected "Callable[[FunctionType, Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:358: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:360: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:369: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:369: error: Argument 1 has incompatible type "Any | CodeType"; expected "Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:406: error: Argument 1 has incompatible type "Callable[[type[Scope], classmethod[Any, Any, Any], ScopeData], Scope | None]"; expected "Callable[[classmethod[Any, Any, Any], Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:406: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:408: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:409: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:409: error: Argument 1 has incompatible type "def (type[Any], /, *Any, **Any) -> Any"; expected "Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:416: error: Argument 1 has incompatible type "Callable[[type[Scope], staticmethod[Any, Any], ScopeData], Scope | None]"; expected "Callable[[staticmethod[Any, Any], Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:416: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:418: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:419: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:419: error: Argument 1 has incompatible type "def (*Any, **Any) -> Any"; expected "Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:426: error: Argument 1 has incompatible type "Callable[[type[Scope], property, ScopeData], Scope | None]"; expected "Callable[[property, Any, ScopeData], Scope | None]"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:426: note: This is likely because "_ of Scope" has named arguments: "cls". Consider marking them positional-only
+ ddtrace/internal/symbol_db/symbols.py:428: error: "self" parameter missing for a non-static method (or an invalid type for self)  [misc]
+ ddtrace/internal/symbol_db/symbols.py:451: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:451: error: Argument 1 has incompatible type "Callable[[Any], Any] | Callable[[Any, Any], None] | Callable[[Any], None]"; expected "Scope | None"  [arg-type]
+ ddtrace/internal/symbol_db/symbols.py:469: error: Too few arguments  [call-arg]
+ ddtrace/internal/symbol_db/symbols.py:469: error: Argument 1 has incompatible type Module; expected "Scope | None"  [arg-type]
+ ddtrace/debugging/_signal/model.py:262: error: Argument 1 to "singledispatch" has incompatible type "Callable[[Probe, FrameType, Thread, Any | None, Meter], Signal]"; expected "Callable[[object, FrameType, Thread, Any | None, Meter], Signal]"  [arg-type]
+ ddtrace/debugging/_signal/model.py:262: note: This is likely because "probe_to_signal" has named arguments: "probe". Consider marking them positional-only

mypy (https://github.com/python/mypy)
+ mypy/stubtest.py:286: error: Argument 1 to "singledispatch" has incompatible type "Callable[[Node | Missing, Any | Missing, list[str]], Iterator[Error]]"; expected "Callable[[object, Any | Missing, list[str]], Iterator[Error]]"  [arg-type]
+ mypy/stubtest.py:286: note: This is likely because "verify" has named arguments: "stub". Consider marking them positional-only
+ mypy/stubtest.py:1221: error: Only concrete class can be given where "type[FuncItem]" is expected  [type-abstract]
+ mypy/stubtest.py:1221: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-type-abstract for more info

mkosi (https://github.com/systemd/mkosi)
+ mkosi/resources/__init__.py:58:2: error: Argument 1 to "singledispatch" has incompatible type "Callable[[Traversable], AbstractContextManager[Path, bool | None]]"; expected "Callable[[object], AbstractContextManager[Path, bool | None]]"  [arg-type]
+ mkosi/resources/__init__.py:58:2: note: This is likely because "as_file" has named arguments: "path". Consider marking them positional-only

sympy (https://github.com/sympy/sympy)
+ sympy/tensor/array/expressions/arrayexpr_derivatives.py:247: error: Only concrete class can be given where "type[MatrixBase]" is expected  [type-abstract]
+ sympy/stats/crv_types.py:153: error: Only concrete class can be given where "type[MatrixBase]" is expected  [type-abstract]

ibis (https://github.com/ibis-project/ibis)
+ ibis/expr/format.py:213: error: Only concrete class can be given where "type[Relation]" is expected  [type-abstract]
+ ibis/expr/format.py:223: error: Only concrete class can be given where "type[PhysicalTable]" is expected  [type-abstract]
+ ibis/expr/format.py:389: error: Only concrete class can be given where "type[Value[Any, Any]]" is expected  [type-abstract]
+ ibis/expr/format.py:400: error: Only concrete class can be given where "type[Binary]" is expected  [type-abstract]
+ ibis/expr/format.py:420: error: Only concrete class can be given where "type[GeoSpatialBinOp]" is expected  [type-abstract]
+ ibis/expr/decompile.py:91: error: Only concrete class can be given where "type[Value[Any, Any]]" is expected  [type-abstract]
+ ibis/expr/decompile.py:258: error: Only concrete class can be given where "type[Reduction]" is expected  [type-abstract]
+ ibis/expr/decompile.py:270: error: Only concrete class can be given where "type[Constant]" is expected  [type-abstract]
+ ibis/expr/types/_rich.py:101: error: Only concrete class can be given where "type[Integer]" is expected  [type-abstract]
+ ibis/expr/types/_rich.py:106: error: Only concrete class can be given where "type[Floating]" is expected  [type-abstract]
+ ibis/backends/polars/compiler.py:1179: error: Only concrete class can be given where "type[Unary]" is expected  [type-abstract]
+ ibis/backends/polars/compiler.py:1269: error: Only concrete class can be given where "type[Binary]" is expected  [type-abstract]
+ ibis/backends/polars/compiler.py:1406: error: Only concrete class can be given where "type[Reference]" is expected  [type-abstract]
+ ibis/backends/polars/compiler.py:1439: error: Only concrete class can be given where "type[ScalarUDF]" is expected  [type-abstract]
+ ibis/backends/polars/compiler.py:1461: error: Only concrete class can be given where "type[AggUDF]" is expected  [type-abstract]

tornado (https://github.com/tornadoweb/tornado)
+ tornado/gen.py:887: error: Incompatible types in assignment (expression has type "_SingleDispatchCallable[[], _asyncio.Future[Any], Callable[[Awaitable[Any] | list[Awaitable[Any]] | dict[Any, Awaitable[Any]] | concurrent.futures._base.Future[Any] | None], _asyncio.Future[Any]]]", variable has type "Callable[[Awaitable[Any] | list[Awaitable[Any]] | dict[Any, Awaitable[Any]] | concurrent.futures._base.Future[Any] | None], _asyncio.Future[Any]]")  [assignment]
+ tornado/gen.py:887: note: "_SingleDispatchCallable[[], _asyncio.Future[Any], Callable[[Awaitable[Any] | list[Awaitable[Any]] | dict[Any, Awaitable[Any]] | concurrent.futures._base.Future[Any] | None], _asyncio.Future[Any]]].__call__" has type "Callable[[object], Future[Any]]"
+ tornado/gen.py:887: error: Argument 1 to "singledispatch" has incompatible type "Callable[[Awaitable[Any] | list[Awaitable[Any]] | dict[Any, Awaitable[Any]] | concurrent.futures._base.Future[Any] | None], _asyncio.Future[Any]]"; expected "Callable[[object], _asyncio.Future[Any]]"  [arg-type]
+ tornado/gen.py:887: note: This is likely because "convert_yielded" has named arguments: "yielded". Consider marking them positional-only