Even if the `self` parameter is defined with another type, it is automatically defined in the body of the function as the type of the object.

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?

Type Checking

Expected Behaviour

test.lua - No error.

---@class Position
---@field x number
---@field y number
---@field z number
Position = {}

---@class Creature
---@field teleportTo fun(self:Creature, position:Position):nil
Creature = {}

---@class Zone
---@field getName fun(self:Zone):string
---@overload fun(): Zone
Zone = {}

---@class Event
---@field onCreatureEnter fun(self:Zone, creature:Creature):nil
---@field onCreatureLeave fun(self:Zone, creature:Creature):nil
---@field register fun(self:Event):nil
---@overload fun(): Event
Event = {}

local zone = Zone()

local zoneEvent = Event()

function zoneEvent:onCreatureEnter(creature)
	if self:getName() == zone:getName() then
		creature:teleportTo(Position(0, 0, 0))
	end
end

zoneEvent:register()

Actual Behaviour

test.lua - Found error.

---@class Position
---@field x number
---@field y number
---@field z number
Position = {}

---@class Creature
---@field teleportTo fun(self:Creature, position:Position):nil
Creature = {}

---@class Zone
---@field getName fun(self:Zone):string
---@overload fun(): Zone
Zone = {}

---@class Event
---@field onCreatureEnter fun(self:Zone, creature:Creature):nil
---@field onCreatureLeave fun(self:Zone, creature:Creature):nil
---@field register fun(self:Event):nil
---@overload fun(): Event
Event = {}

local zone = Zone()

local zoneEvent = Event()

function zoneEvent:onCreatureEnter(creature)
	if self:getName() == zone:getName() then
		creature:teleportTo(Position(0, 0, 0))
	end
end

zoneEvent:register()

Reproduction steps

Just copy the code and test it in any Lua file.
self should be of type Zone, as that's how it's defined in the meta file.

Additional Notes

No response

Log File

No response

Reproduce the issue in the Lua language server through the Visual Studio Code extension using the provided test.lua example. Start by tracing type checking for colon-defined methods and the annotated self parameter; done means self is treated as Zone and the example produces no error.