LuaLS / LuaLS/lua-language-server

Unexpected generic behaviour

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Dominant language
Lua
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Description

### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

MacOS

### What is the issue affecting?

Annotations

### Expected Behaviour

```lua
local ffi = require("ffi")

---@generic T
---@param ct `T`
---@return fun(x: T): `T`*
local function ref(ct)
return function (init)
return ffi.new(ct.."[1]", {init})
end
end

ffi.cdef [[
typedef struct MyStruct {
int a, b;
} MyStruct;
]]

---@class MyStruct
---@field a integer
---@field b integer

---@class MyStruct* : { [integer] : MyStruct }, ffi.cdata*

local x = ffi.ref "MyStruct" {
a = 4,
b = 2
}

--type of `x` expected to be `MyStruct*`
```

### Actual Behaviour

type of `x` is `MyStruct`

### Reproduction steps

Run the code and check types

### Additional Notes

_No response_

### Log File

_No response_

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the annotation example in the Visual Studio Code extension and inspect how the generic return type and FFI class annotations are inferred. Compare the inferred type of x with the expected MyStruct* result; done means the example reports x as MyStruct* rather than MyStruct.

Written by the indexing model from the issue text.

Assessment

Tech stack
lua
Domain
devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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