If clause overwrites number like class type on variable

[muppet9010]

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

I wouldn't expect doing an if check on a variable to change its type.

I am using this with the Factorio game API which includes a lot of number or integer like types for subsets of these. I have included an example typedef for one of these.

In 3.5.x this code wasn't warned about, but in 3.6.1 it is.

Actual Behaviour

The type of my variables are being overwritten by the type that they are compared to in an if statement. The work around I found was to type all of these comparison values, but it feels a bit clunky.

Reproduction steps

---@class ASmallNumber # A double type number between 0 and 1 inclusive.

---@param aSmallNumber1 ASmallNumber
---@param aSmallNumber2 ASmallNumber
local aFunc = function(aSmallNumber1, aSmallNumber2)
    ---@type ASmallNumber, ASmallNumber, ASmallNumber
    local aNumber1, aNumber2, aNumber3

    if aSmallNumber1 == 0.25 or aSmallNumber1 == 0.5 then
        aNumber2 = aSmallNumber1 -- This is complained about: This variable is defined as type `ASmallNumber`. Cannot convert         its type to `number`.Lua Diagnostics.(cast-local-type)
        -- aSmallerNumber1 has a type of `number` here, but I explicitly defined it in the function param as being type `ASmallNumber`.
    end

    if aSmallNumber2 == (0.25) --[[@as ASmallNumber]] or aSmallNumber2 == (0.5) --[[@as ASmallNumber]] then
        aNumber3 = aSmallNumber2
        -- As I typed the `if` comparison values this is fine as the `aSmallNumber2` variable still has a type of `ASmallNumber`.
    end
end

The same occurs with just a locally defined variable that has its type and value set as type ASmallNumber. When comparing with an equivilent if the explicitly defined type is overridden.

local aSmallNumber = 0.5 --[[@as ASmallNumber]] ---@type ASmallNumber

Additional Notes

Fuller local variable example:

---@type ASmallNumber
local aNumber = 0.5 --[[@as ASmallNumber]]
---@type ASmallNumber
local aSecondNumber = 0.5 --[[@as ASmallNumber]]

---@param smallNumberValue ASmallNumber
local funcRequiringASmallNumber = function(smallNumberValue) end

if aNumber == 0.25 or aNumber == 0.5 then
    funcRequiringASmallNumber(aNumber)
end

if aSecondNumber == (0.25) --[[@as ASmallNumber]] or aSecondNumber == (0.5) --[[@as ASmallNumber]] then
    funcRequiringASmallNumber(aSecondNumber)
end

Log File

No response

[sumneko]

If your class is defined by ---@class ASmallNumber: number?

[sumneko]

---@class SmallNumber: number
---@class Integer: number

---@type SmallNumber, Integer
local x, y

if x == 0.1 and y == 0.1 then
    print(x, y) --> What are the types for x and y here?
end