Type narrowing breaks on equivalence to false.

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

When x is a boolean, if x == false then should identify x as false in its true block, and true in its false block.

Actual Behaviour

In the true block, x is identified as true, and in the false block, x is identified as boolean.

Reproduction steps

1. Paste this code into the editor

local x ---@type boolean

if x == false then
	local y = x
	-- y is type `true`, should be type `false`
else
	local y = x
	-- y is type 'boolean', should be type 'true'
end

2. Hover over y to inspect its type.

Additional Notes

This doesn't just happen with boolean types. It can happen to any type that can be false, such as integer|false|nil.

Log File

No response

使用 Lua 代码片段在 Visual Studio Code 扩展中重现该问题，并在两个分支中将鼠标悬停在 y 上。跟踪 x == false 的类型检查行为，然后验证 true 分支解析为 false，false 分支解析为 true，包括 integer|false|nil 这样的联合类型。