Issues with booleans

[firas-assaad]

Describe the bug
In certain cases, boolean inferred values don't work as expected. This usually happens when calling functions that don't have explicit @return annotations and that return true or false explicitly (e.g. return false).

To Reproduce
Example 1:

---@param int integer
local function x(int)
end

local function y()
    if math.random() > 0.5 then
        return true
    else
        return false
    end
end

local bool = y()
local should_be_int = bool and 300 or 500
x(should_be_int) 
-- Warning: Cannot assign `integer|true` to parameter `integer`.Lua Diagnostics.(param-type-mismatch)

should_be_int is inferred as integer|true. If I annotate the function y with @return boolean or if function y is rewritten as return math.random() > 0.5, then should_be_int is correctly deduced as integer.

Example 2:

local function y()
    if math.random() < 0.5 then
        return true
    else
        return false
    end
end

---@return boolean
local function x()
    local bool = true

    bool = y()

    bool = bool and y()

    if bool then
        print(1)
    end

    return bool
    -- Warning: The type of the 1 return value is `boolean`, but the actual return is `boolean|true|false`
end

The variable bool is inferred as boolean|true|false which is somehow incompatible with the specified @return. If I remove the @return annotation, or if the y function doesn't explicitly return true/false, or if you change the body of the function x, the warning does not happen.

Expected behavior
The boolean return types should be treated the same in all cases.

Screenshots
I wrote down the warnings in the code snippets, but if you want screenshots let me know.

Environment (please complete the following information):

• OS: Windows 10
• Is WSL remote? No
• Client: VSCode 1.68.1
• lua-language-server version v3.4.2

[dganzella]

I really do not understand this.

I have this method in my code

---@param self objectPoolManager
---@param tmxId integer
---@param map string
---@return boolean
function objectPoolManager:hasTmxObject(tmxId, map)
    return self.objectRefTable[map] ~= nil and self.objectRefTable[map][tmxId] ~= nil
end

and it gives error:

Annotations specify that return value #1 has a type of `boolean`, returning value of type `boolean` here instead.

I have to downgrade all the way to 3.4.2 to make this error disappear. what am I doing wrong? the error message is completely nonsensical

@firas-assaad if you could explain me what should be done since you asked for this change

@sumneko if you can provide a fix or explain what is wrong in the code and what I need to change that can help, im pretty sure more people will have the same doubt

[firas-assaad]

@dganzella I don't think your issue is related to this one (which was fixed long ago). I suggest creating a new issue with additional information and a longer example (where objectRefTable is defined, for example).

I don't get any errors with your example but it might depend on how objectRefTable is defined.