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

Lua スニペットを使用して Visual Studio Code 拡張機能で問題を再現し、両方の分岐で y にカーソルを合わせます。x == false に対する型チェックの動作を追跡し、その後、true 分岐が false に、false 分岐が true に解決されることを、integer|false|nil のようなユニオンも含めて確認します。