Runtime Lua version detection without _VERSION

LuaVersion.lua

local function luaVersion()
    local f = function()
        return function() end
    end
    
    if 0xffffffffffffffffffffffffffffffffffffffffffffff == 2 ^ 64 then
        return "Luau"
    end

    if ({nil,[1] = true})[1] then
        return "LuaJIT"
    end

    if 1/0 == 1/"-0" then
        return ("1" + "2").."" == "3.0" and "Lua 5.3" or "Lua 5.4"
    end

    return f() == f() and "Lua 5.2" or "Lua 5.1"
end

print(luaVersion())