Overload intellise prototype issue with meta functions

[Rathoz]

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Type Checking

Expected Behaviour

type of b should be string

Actual Behaviour

type of b is string|nil

Reproduction steps

---@meta
local Foo = {}
---@overload fun(a: string): string
---@overload fun(a: number): table
function Foo.Bar(a)
end

local b = Foo.Bar('abc') -- type of is `string|nil`

Additional Notes

Log File

No response

[tomlau10]

I think that's because you did not define the base type of the function, so LuaLs just infer the base type by itself, that this empty function can return nil. To workaround this, you may change one of the ---@overload declaration into ---@param and ---@return:

---@meta
local Foo = {}

---@param a string
---@return string
---@overload fun(a: number): table
function Foo.Bar(a)
end

local b = Foo.Bar('abc') -- type of is `string` now

[Rathoz]

I know why it happens and I know that there's a workaround ;)

Doesn't mean it shouldn't be bug reported