Local reference to enum defined in an object from a different file, same workspace

[erunehtar]

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?

Diagnostics/Syntax Checking

Expected Behaviour

file1.lua

local module = ...

---@enum Module.Color
module.Color = {
    White = "ffffffff",
    Black = "ff000000",
    Yellow = etc...
}

file2.lua

local module = ...

---@type Module.Color
local Color = module.Color

---@param color Module.Color
local function SetColor(color)
    -- code ...
end

---@param text string
local function Print(text)
    SetColor(Color.Blue) -- no diagnostic errors
end

Actual Behaviour

file1.lua

local module = ...

---@enum Module.Color
module.Color = {
    White = "ffffffff",
    Black = "ff000000",
    Yellow = etc...
}

file2.lua

local module = ...

---@type Module.Color
local Color = module.Color

---@param color Module.Color
local function SetColor(color)
    -- code ...
end

---@param text string
local function Print(text)
    SetColor(Color.Blue) -- Undefined field `Blue`. Lua Diagnostics.(undefined-field)
end

Reproduction steps

Simply make a local reference to an enum defined in a table, try to use it.

Additional Notes

I want to share an enum across lua files and have a reference on it so that I can type Color.Blue instead of module.Color.Blue. Lua allows me to have a local reference, doing local Color = module.Color compile and works just fine, but the diagnostic is not happy, marking the local reference as ---@type Module.Color doesn't seem enough.

I feel like I might be doing this wrong, is there a syntax to achieve what I am trying to do? I cannot put the enum Color in global space, I have to put it in the module object, so that it does not clash with other modules.

Log File

No response

[erunehtar]

I was able to workaround it by doing:

file1.lua

local module = ...

---@alias Module.Color string
---@alias Module.ColorEnum table<string, Module.Color>

---@type Module.ColorEnum
module.Color = {
    White = "ffffffff",
    Black = "ff000000",
    Yellow = etc...
}

file2.lua

local module = ...

---@type Module.ColorEnum
local Color = module.Color

Basically, skip using @enum and make up a custom enum declaration. However this lose the enum validation, since now using ---@param Module.Color allows for any string to be passed to the function.

Please let me know if this can be achieved using @enum with some syntax I could not figure out.

[tomlau10]

I believe you misused the @enum.
please see #3151 (comment)

---

And if your module.lua already return that module table, you actually don't need @type at all 🤔

• module.lua

local module = {}

---@enum Module.Color
module.Color = {
    White = "ffffffff",
    Black = "ff000000",
}

return module

• main.lua

local module = require "module"

-- the server already know the type of `module.Color`
local Color = module.Color

print(Color.Black)
print(Color.NoSuchColor) --<< warning: undefined field

[erunehtar]

Sorry I forgot to mention that there is no return module nor require "module" in my Lua environment (this is WoW Lua 5.1 environment), and the way the "module" object is passed around is by providing it as an argument when they load the lua file, we get the "module" by fetching it with local moduleName, module = ... at the top of each lua file of the project.

Would this environment cause issues with how the Lua language server process types across units?

But in any case, that comment you posted indeed contained the solution to my issue! And I don't even need the ---@type anymore in file2.lua, which is even better. ❤️ thank you very much!

Here is the full working syntax if anyone ever search for this again (the key was really the ---@class and .* combinaison) :

file1.lua

local moduleName, module = ... ---@cast module Module

---@class Module
---@field Color Module.Color.*

---@enum Module.Color
local Color = { ---@class Module.Color.*
    White = "ffffffff",
    Black = "ff000000",
    Yellow = etc...
}
module.Color = Color

file2.lua

local moduleName, module = ... ---@cast module Module

local Color = module.Color

---@param color Module.Color
local function SetColor(color)
    -- code ...
end

---@param text string
local function Print(text)
    SetColor(Color.Blue) -- no diagnostic errors, yay! =D
end