.luacheckrc alternative for LuaLS?

[Kein]

luachek has a handy .luacheckrc that allows you to declare some global/default stds for type checks.
Is there something similar for LuaLS's .luarc.json? I've tried reading docs but .luarc.json mentioned like 2 times there.

My issue is that I have a lot of stubs generated for type hints and type check and luals reads them but incorrectly, complaining that some defined functions missing or failing at inheritance types.

[tomlau10]

• Are you looking for runtime.version which allows you to set lua runtime version like luajit / lua5.4? https://luals.github.io/wiki/settings/#runtimeversion

• Or are you trying to include some libraries like love2d in your project?
  You may have to use the addon manager to install related meta files and link them using workspace.library settings:
  https://luals.github.io/wiki/addons/#addon-manager

---

My issue is that I have a lot of stubs generated for type hints and type check and luals reads them but incorrectly, complaining that some defined functions missing or failing at inheritance types.

Can you post some part of your code, or some minimal examples?

[Kein]

No, it just some auto-generated stubs for the external API. luacheck used to have global namespaces via .luacheckrc to declare stuff you know exist, i.e.

std = "min + MyModule"
stds.MyModule =
{
  read_globals = {  },
  globals =
  {
    RegisterHook = { },
    RegisterBeginPlayPostHook = {},
    StaticFindObject = {},
    ExecuteInGameThread = {},
  }
}

So what I have for my LUA (_luals) project is bunch of gen'd stubs like
https://github.com/UE4SS-RE/RE-UE4SS/blob/main/assets/Mods/shared/UEHelpers/UEHelpers.lua
or
https://github.com/UE4SS-RE/RE-UE4SS/blob/main/assets/Mods/shared/Types.lua

I've generated extra stubs file with declaration

---@class UAssetRegistryHelpers : UObject
UAssetRegistryHelpers = {}

it is defined in Types.lua above as

---@class UObject : RemoteObject
UObject = {}

Yet LuaLS diagnostic return me a waring:

which does not make much sense.

[tomlau10]

luacheck used to have global namespaces via .luacheckrc to declare stuff you know exist

For global variables, luals has a diagnostics.globals setting: https://luals.github.io/wiki/settings/#diagnosticsglobals

{
  "diagnostics.globals": [
    "RegisterHook",
    "RegisterBeginPlayPostHook",
    "StaticFindObject",
    "ExecuteInGameThread",
  ]
}

But it's for suppressing Undefined global warnings only.
If you want them to be typed, then you have to write Definition Files for them: https://luals.github.io/wiki/definition-files/

• some_directory/MyModule.lua

---@meta

---@param a integer
---@param b string
---@return boolean
function RegisterHook(a, b) end

• and then you can set this some_directory/ path in your workspace.library config inside .luarc.json.
  LuaLS will load them as well when loading the workspace

{
    "workspace.library": [
        "some_directory/"
    ],
}

---

Yet LuaLS diagnostic return me a waring:

May I know what's the exact line that are causing this warning?
You screenshot only captures the warning message, and didn't show the problematic code 😂

Judging from the screenshot, the warning is cast-local-type: https://luals.github.io/wiki/diagnostics/#cast-local-type
You are assigning an incorrect type to an already typed variable. For example:

---@class UAssetRegistryHelpers : UObject
UAssetRegistryHelpers = {}

---@type UObject
local object

---@type UAssetRegistryHelpers
local AssetRegistryHelpers

AssetRegistryHelpers = object --< this line will generate the exact `cast-local-type` warning as your screenshot

• this is because UObject is superclass of UAssetRegistryHelpers, and in general a superclass object cannot be assigned to subclass object
  (on the otherhand, a subclass object can be casted to its superclass)
• for the above sample code, if you are sure that object can be casted as UAssetRegistryHelpers, you can use @as: https://luals.github.io/wiki/annotations/#as

AssetRegistryHelpers = object   --[[@as UAssetRegistryHelpers]]

or @cast to manually cast the object before assigning: https://luals.github.io/wiki/annotations/#cast

---@cast object UAssetRegistryHelpers
AssetRegistryHelpers = object

[Kein]

and then you can set this some_directory/ path in your workspace.library config inside .luarc.json.
LuaLS will load them as well when loading the workspace

Yeah, I have this set.

AssetRegistryHelpers = object --[[@as UAssetRegistryHelpers]]

Yeah, this works but now it ignores inherited functions, claiming they do not exist or making an overloaded one with argument to take full precedent.

May I know what's the exact line that are causing this warning?

local AssetRegistryHelpers = nil ---@type UAssetRegistryHelpers
AssetRegistryHelpers = StaticFindObject("/Script/AssetRegistry.Default__AssetRegistryHelpers")

StaticFindObject returns UObject, which is super of UAssetRegistryHelpers down the line. UObject is:

---@class UObject : RemoteObject

---Returns whether this object is valid or not
---@return boolean
function RemoteObject:IsValid() end

and the latter has defined function boolean isValid() but in this case UAssetRegistryHelpers has an overload boolean isValid(arg) which for some reason takes precedence and warns that argument is needed.

I'm just trying to cut down on all false-positives

[tomlau10]

local AssetRegistryHelpers = nil ---@type UAssetRegistryHelpers
AssetRegistryHelpers = StaticFindObject("/Script/AssetRegistry.Default__AssetRegistryHelpers")

StaticFindObject returns UObject, which is super of UAssetRegistryHelpers down the line.

Ok~ so this is the line which causes the cast-local-type warning. An I think it is a true-positive, because as you said UObject is super of UAssetRegistryHelpers. And in general we cannot auto cast a superclass to a narrowed subclass.
=> LuaLS is working correctly in this case, agree?

---

Yeah, this works but now it ignores inherited functions, claiming they do not exist or making an overloaded one with argument to take full precedent.
...
has an overload boolean isValid(arg) which for some reason takes precedence and warns that argument is needed.

And then if I understand correctly, you don't want to write --[[@as UAssetRegistryHelpers]]. Because in your case UAssetRegistryHelpers has an overload :isValid(arg), say something like this:

---@class UAssetRegistryHelpers : UObject
UAssetRegistryHelpers = {}

---@param arg string
function UAssetRegistryHelpers:IsValid(arg) end

• and this override the original RemoteObject:IsValid()
• such that when you write AssetRegistryHelpers:IsValid(), LuaLS will throw missing-parameter warning

---@type UAssetRegistryHelpers
local AssetRegistryHelpers = {}
AssetRegistryHelpers:IsValid() -- missing-parameter: This function requires 2 argument(s) but instead it is receiving 1.

---

If that's the case, I think you might have some misunderstandings on how inheritance works in LuaLS:

• the same named method will overwrite the signature of the method in super class, instead of adding a overload
• so once you define UAssetRegistryHelpers:IsValid(arg), there will be no more UAssetRegistryHelpers:IsValid() in this UAssetRegistryHelpers class
• however in order to solve this very specific case, where you want arg to be optional, it's actually very simple 😄
  you just need to annotate the arg param with ? (optional)

---@class UAssetRegistryHelpers : UObject
UAssetRegistryHelpers = {}

---@param arg string? <<< note the `?` after `string`
function UAssetRegistryHelpers:IsValid(arg) end

---@type UAssetRegistryHelpers
local AssetRegistryHelpers = {}
AssetRegistryHelpers:IsValid() -- should be ok now

• maybe you need to review the param annotation of all you overloaded functions in your custom UAssetRegistryHelpers class 🤔
  as you might have thought they are added as an overload, but not, they will just overwrite the function signature of superclass.
  And finally you can use the --[[@as]] trick to silent the cast-local-type warning.

[Kein]

Ok~ so this is the line which causes the cast-local-type warning. An I think it is a true-positive, because as you said UObject is super of UAssetRegistryHelpers. And in general we cannot auto cast a superclass to a narrowed subclass.

Yeah, you are right, it is a valid case, the cast-thing is what I was looking for.

however in order to solve this very specific case, where you want arg to be optional, it's actually very simple

Not exactly the same but this will do, beggars, choosers, etc :P