Modifying local reference of a table does not update the table in other files

[Poltergeist-ix]

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?

Other

Expected Behaviour

See the changes to table in all files.

Actual Behaviour

The changes do not appear in other files when modifying the local reference.

Reproduction steps

File 1:

MyTable = {zx = 1}

File 2:

require "Ready"
local MyTable = MyTable
MyTable.test = {a = "abc"}

File 3:

require "Set"
local MyTable = MyTable

However if file 2 does not use a local reference then it works as expected.

Additional Notes

No response

Log File

No response

[Poltergeist-ix]

Worth mentioning similar issue happens with

require("Ready").test = {a = "abc"}

[tomlau10]

IIUC, luals doesn't run your actual code, it just tries its best to infer the types.
I guess for global variables, it is tracking all setglobal operation on the same name variable, to infer all its fields.

Consider the following:

• file1

MyTable = {a = 1}
MyTable.a = nil

• file2

MyTable = {b = 2}
MyTable.b = nil

• file3

print(MyTable) --> what type of `MyTable` do you expect here?
-- only with field `a`?
-- only with field `b`?
-- no field at all?

no, the result is

(global) MyTable: {
    a: integer = 1,
    b: integer = 2,
}

because the server just traces all setglobal operations across all the files in your workspace.

---

By aliasing the global variable with a local, luals can no longer relies on the setglobal on same name variable method. Because a local variable can be with any other valid name, or even you can have that local variable points to something else and come back to points to global variable again.

Proper annotation

If you want luals to know that you are injecting fields into the same type, I think you should add proper @class annotation:

• file1

---@class MyTable
MyTable = {zx = 1}

• file2

require "Ready"
---@class MyTable
local MyTable = MyTable
MyTable.test = {a = "abc"}

• file3

require "Set"
local MyTable = MyTable
-- now `MyTable` has the class type `MyTable`, has both fields `zx` and `a`

MyTable.b = 2 --> warning: Fields cannot be injected into the reference of `MyTable` for `b`. To do so, use `---@class` for `MyTable`.
-- i.e. unless you add the `---@class` like file 2, otherwise luals forbids you to inject field into an already typed variable
-- otherwise any operation you did here will not reflect to the type system

PS: I just recently learnt that this is the C# partial class concept, where you can split the definition of a class in multiple files. Our team has been widely adopting this coding pattern before I even know there is a name for this concept 😂

[Poltergeist-ix]

Thank you for reply, it's so nice to have this working now.