Generics don't expand alias types/don't work with other parameters

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

With a code sample like this:

---@alias TestFunction fun(abc: string): integer

---@generic T
---@param name `T`
---@param func T
local function testSecond(name, func) end

testSecond("TestFunction", function(abc) end)

I would expect abc to have a type of string, and the function to be type checked and require a return.

Actual Behaviour

Instead, abc has the any type and the function requires no return.
I further tested with a different code sample:

---@alias TestFunction fun(abc: string): integer

---@generic T
---@param name `T`
---@return T
local function testSecond(name, func) return function(abc) end end

local cool = testSecond("TestFunction", function(abc) end)
cool()

This shows no warnings and does not require me to pass any arguments to cool(), which is incorrect. Hovering over cool provides a type of 'TestFunction' and does not show the full expanded type of the alias, unlike other variables with a type of an alias. That rings the same with this code sample I also tested:

---@alias TestFunction fun(abc: string): integer

---@generic T
---@param name `T`
---@param func fun(cool: T)
local function testSecond(name, func) end

testSecond("TestFunction", function(abc) end)

where hovering over abc provides me with a 'TestFunction' unexpanded type.
However, correct behavior is seen with the following code sample using the base string type;

---@alias TestFunction fun(abc: string): integer

---@generic T
---@param name `T`
---@param func fun(cool: T)
---@return T
local function testSecond(name, func) end

local cool = testSecond("string", function(abc) abc.cool = "hi" end)
local testfind = cool:find("test")

Autocomplete is provided for :find() and abc.cool = "hi" throws the correct warning for field injection.
And most confusing of all, this code sample behaves in line with expected behavior, and the alias is fully expanded.

---@alias TestFunction fun(abc: string): integer

---@generic T
---@param name `T`
---@param func fun(cool: T)
---@return T
local function testSecond(name, func) end

local cool = testSecond("TestFunction",
    ---@param abc TestFunction
    function(abc)
        abc()
    end
)

This also doesn't work, which I kind of expected. (no warnings)

Reproduction steps

1. Paste code into project with Lua LSP on, see issue

Additional Notes

No response

Log File

No response

まず、LuaLS を使用する Visual Studio Code Extension の例を再現し、ジェネリックパラメーターと aliased function types の型チェックに焦点を当てます。TestFunction を使用するケースと、基底の string 型を使用するケースを比較します。エイリアスが一貫して展開され、コールバックパラメーターが期待される型を受け取り、無効な呼び出しや戻り値の不足によって警告が生成されれば完了です。