Remove Any from _NotImplementedType inheritance

[davidhalter]

It does seem like this was first added in ecb4314 and does not serve a bigger purpose.

I hope the fallout is not too big in Mypy primer, but we'll see.

[davidhalter]

Nevermind, there are probably a lot of issues around this, because we want to be able to return this in all __eq__ methods.

Closing, because this is clearly the wrong idea if we don't want to do quite a bit of work in type checkers (even though I personally don't like the Any in there).

[github-actions]

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

Tanjun (https://github.com/FasterSpeeding/Tanjun)
+ tanjun/annotations.py:2324: error: Dict entry 0 has incompatible type "type[Attachment]": "_NotImplementedType"; expected "Any": "tuple[Callable[..., Any], ...]"  [dict-item]
+ tanjun/annotations.py:2326: error: Dict entry 2 has incompatible type "type[PartialChannel]": "_NotImplementedType"; expected "Any": "tuple[Callable[..., Any], ...]"  [dict-item]
+ tanjun/annotations.py:2327: error: Dict entry 3 has incompatible type "type[InteractionChannel]": "_NotImplementedType"; expected "Any": "tuple[Callable[..., Any], ...]"  [dict-item]
+ tanjun/annotations.py:2331: error: Dict entry 7 has incompatible type "type[InteractionMember]": "_NotImplementedType"; expected "Any": "tuple[Callable[..., Any], ...]"  [dict-item]
+ tanjun/annotations.py:2451: error: Non-overlapping identity check (left operand type: "tuple[Callable[..., Any], ...]", right operand type: "_NotImplementedType")  [comparison-overlap]

scipy (https://github.com/scipy/scipy)
+ scipy/optimize/_trustregion_constr/report.py:4: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "list[str]")  [assignment]
+ scipy/optimize/_trustregion_constr/report.py:5: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "list[int]")  [assignment]
+ scipy/optimize/_trustregion_constr/report.py:6: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "list[str]")  [assignment]
+ scipy/integrate/_ivp/rk.py:76: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "ndarray[Any, Any]")  [assignment]
+ scipy/integrate/_ivp/rk.py:77: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "ndarray[Any, Any]")  [assignment]
+ scipy/integrate/_ivp/rk.py:78: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "ndarray[Any, Any]")  [assignment]
+ scipy/integrate/_ivp/rk.py:79: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "ndarray[Any, Any]")  [assignment]
+ scipy/integrate/_ivp/rk.py:80: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "ndarray[Any, Any]")  [assignment]
+ scipy/integrate/_ivp/rk.py:81: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "int")  [assignment]
+ scipy/integrate/_ivp/rk.py:82: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "int")  [assignment]
+ scipy/integrate/_ivp/rk.py:83: error: Incompatible types in assignment (expression has type "_NotImplementedType", variable has type "int")  [assignment]

beartype (https://github.com/beartype/beartype)
- beartype/_conf/confcls.py:1276: error: Unused "type: ignore" comment  [unused-ignore]
- beartype/_check/metadata/metasane.py:183: error: Unused "type: ignore" comment  [unused-ignore]

manticore (https://github.com/trailofbits/manticore)
+ manticore/platforms/linux.py:328: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:331: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:334: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:341: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:344: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:347: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:350: error: Exception must be derived from BaseException  [misc]
+ manticore/platforms/linux.py:353: error: Exception must be derived from BaseException  [misc]

[JelleZijlstra]

Yes, this is probably necessary until we gain some smarter handling for NotImplemented in dunders.

The primer output is surprisingly small though, and at least some of them are true positives (e.g. the manticore ones are raise NotImplemented that should be NotImplementedError). So maybe there's other special casing in mypy that makes this more tractable than it would seem.

[davidhalter]

Yes, it is indeed very surprising how low the fallout is.

I stumbled upon this, because Mypy was fixing the case around manticore and I tried to implement it in my Mypy rewrite in Rust, see python/mypy#17890.