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

首先，在使用 LuaLS 的 Visual Studio Code Extension 中重現這些範例，重點關注泛型參數和 aliased function types 的型別檢查。比較使用 TestFunction 的情況與使用基礎 string 型別的情況。完成的標準是：別名能夠一致地展開，回呼參數能夠取得預期型別，並且無效呼叫或缺少回傳值時會產生警告。