@alias comments aren't visible

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?

Annotations, Hover

Expected Behaviour

a comment to an alias type should be shown as regular comment to a parameter would be shown (at least if there is no comment to the @param annotation itself). The hover message should read:

function f(arg: string)
@param arg — comment from alias

Unused functions.Lua Diagnostics.(unused-function)
Unused local `f`.Lua Diagnostics.(unused-local)

Actual Behaviour

the comment to the alias type isn't shown. the hover message is:

function f(arg: string)
Unused functions.Lua Diagnostics.(unused-function)
Unused local `f`.Lua Diagnostics.(unused-local)

Reproduction steps

1. cat << EOF > file.lua
   ---@alias t_arg string comment from alias
   ---@param arg t_arg
   local function f(arg)
   end
   EOF
2. code file.lua
3. hover over the function name and read message

使用所示的 @alias 和 @param 注释在 file.lua 中复现该问题，然后检查函数文档的 hover 入口点。完成标准是：将鼠标悬停在 f 上时包含作为 @param arg 的别名注释，同时保留现有诊断并遵循任何显式的 @param 注释。