cannot extend generic class

[somebody1234]

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Linux

What is the issue affecting?

Type Checking

Expected Behaviour

inheritance works, or error diagnostic

Actual Behaviour

inheritance doesnt work, no diagnostic

Reproduction steps

--- @class Foo<t>: { a: t; }
--- @class Bar: Foo<integer>
local x --- @type Bar
local what = x.a -- type is unknown

Additional Notes

seems like it just doesnt handle generic syntax in : here?

Log File

No response

[carsakiller]

There are just so many issues about generics and generic classes 😰

Going to close this one as a duplicate of #1863 or #1378

[somebody1234]

@carsakiller saw those from the generics super issue, but afaict this is a different issue

[somebody1234]

the issue here is : Foo<t> just flat out doesn't work

[carsakiller]

Yes, but the bottom line is really that --- @class Foo<t>: { a: t } doesn't work because generic classes are not supported. The ---@class Child: Parent syntax is supported elsewhere, so when generic classes are implemented, Child : Parent<T> should also work. This is the first time I have seen this syntax mentioned though, I think, so I'll add it to the list just so we can make sure it receives some attention.

Just trying to keep things organized—there are so many similar issues with slight variations 😄

[somebody1234]

i was assuming it does work though:

• the docs mention it
  • (the builtin table and array are generic classes afaict)
• it works if you're not doing : Foo<t>

[carsakiller]

I see, I thought the generic class was not working when inheriting { a: t } as well. It seems it does though.

--- @class Foo<t>: { a: t; }

---@type Foo<integer>
local x
print(x.a) -- Type is integer


---@class Bar : Foo<integer>

---@type Bar
local y
print(y.a) -- undefined field `a`