Indexing a table by an enum's value

[vallode]

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Linux

What is the issue affecting?

Diagnostics/Syntax Checking

Expected Behaviour

Types defined with an enum as their key should be accessible via both the runtime enum itself and the value they represent.

Actual Behaviour

A type defined with an enum as its key cannot be accessed with the enum's value.

Reproduction steps

---@enum building_id
local building_id = {
    ANY = -1,
    ONE = 0,
    TWO = 1,
}

---@type { [building_id]: { name: string } }
local building_attributes = {}

local anyName = building_attributes[building_id.ANY].name // Typed as "string"
local anyName = building_attributes[-1].name // Typed as "unknown"

Additional Notes

Discussed in https://github.com/LuaLS/lua-language-server/discussions/2402

Log File

No response

[C3pa]

IMHO, the core issue here is that the Lua language server currently doesn't infer types after indexing arrays (and maybe hash tables?).

The same problem was first reported in #1643 and later in #2030. That's also actually needed to fully implement feature #1081.