Missing "need-check-nil" on self fields

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, Diagnostics/Syntax Checking

Expected Behaviour

I expect both methods to report the "need check nil" diagnostic:

---@class Y
---@field z string

---@class X
---@field y Y?
local X = {}

function X:no_warning()
    print(self.y.z) -- no diagnostics
end

function X:warning()
    local y = self.y
    print(y.z) -- need-check-nil
end

Actual Behaviour

The potential problem is only reported when using a local variable.

Reproduction steps

Try the code above. and note how only the first method (no_warning) works without any diagnostics.

Additional Notes

No response

Log File

No response

使用報告中的 Lua 程式碼片段在 Visual Studio Code 擴充功能中重現問題，並比較 self.y.z 與區域變數案例 y.z 的診斷結果。追蹤負責 nil 檢查的型別檢查或診斷進入點；完成標準是兩個方法都回報 need-check-nil 診斷，且不變更範例中的型別。