LuaLS / LuaLS/lua-language-server

Needs a "don't use truthy types in a conditional/boolean context" diagnostic

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還沒有人認領這個 Issue。

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Lua
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描述

### 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

When variable `a` has a truthy type (e.g. any type that does not contain `boolean` or `nil`), then the following lines should all give warnings, since (assuming the type annotations are correct and `Weak Nil Check` is off) `a` cannot be `nil` or `false`, and thus can never resolve to `false` in a boolean context, and so the operations are pointless:
```lua
if a then print("1") end -- will always print 1
if not a then print("2") end -- will never print 2
local b = a or "3" -- equivalent to b = a
local c = a and "4" or "5" -- equivalent to c = "4"
```

### Actual Behaviour

None of those lines warn you about anything under the current diagnostics

### Reproduction steps

1. Type the following into a lua file:
```lua
---@param a number (or string, table, etc.)
function A(a)
if a then print("1") end
if not a then print("2") end
local b = a or "3"
local c = a and "4" or "5"
end
```
2. Observe the lack of diagnostic warnings on each line inside the function

(I would also like a "no-unparameterized-tables" diagnostic where plain `table` without any <> does not count as a valid type)

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  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
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研究方向

先透過 Visual Studio Code 擴充功能,在 Lua 檔案中重現提供的 Lua 程式碼片段,然後追蹤處理條件式與布林運算式的型別檢查和診斷入口點。完成的標準是所要求的案例會產生適當的警告;另外也需要決定獨立的 no-unparameterized-tables 請求範圍。

由索引模型根據 Issue 內容生成。

評估

技術堆疊
lua
領域
tooling
Issue 類型
功能
難度
4/5
預估耗時
3-5 天
活躍度
停滯
描述清晰度
基本清楚
新手友好度
38/100

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