Apologies, I removed the *Ts syntax unit test for now, obviously that doesn't work for older Python versions... Should perhaps live in check-python311.test? I'm still not entirely clear on the logic behind which test goes where, to be honest.

Should perhaps live in check-python311.test

Yes, every test that depends on python version higher than minimal supported version (3.9 now) should live in check-python*.test files (matching the minimal version where such syntax is supported)

@sterliakov Thanks for taking a look, and for the suggestion. I've moved the tests using *Ts syntax into check-python311.test.

@sterliakov Sorry to ping you again, but perhaps you could review this PR or maybe suggest a member who could? For what it's worth, the code change is pretty minimal and the test coverage should be sufficient, IMHO. Thanks in advance!

Thanks @sterliakov!

About the NamedTuple analogy, there is a similar test for it being Generic with TypeVarTuple argument here but only directly, not propagated via inheritance. Which makes sense, I think, as NamedTuples don't behave the same way as TypedDicts do when subclassed (which isn't actually what happens, but you probably get what I mean):

class MyDict(TypedDict):
    foo: int

class MySubDict(MyDict):
    bar: int


msd = MySubDict(foo=1, bar=2)  # Fine



class MyTuple(NamedTuple):
    foo: int

class MySubTuple(MyTuple):
    bar: int


mst = MySubTuple(foo=1, bar=2)  # Error: unexpected keyword "bar"

I sometimes think it would be nice to be able to extend NamedTuples this way, but think I understand why it doesn't currently work that way.

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

@hauntsaninja
I hope you don't mind my pinging you directly; your name was suggested by @sterliakov above. If you have a little time, I would greatly appreciate if you could take a look at this!

I understand that (apparently) this isn't an issue that many folks run into, but I think you'll agree that it actually is a bug that may as well be fixed. I've rebased the branch to latest master just now.