Type inference not working for @field and @type function declarations in method overrides #3367

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?

Type Inference

Expected Behaviour

When a child class overrides a parent class method that was declared using @field or @type annotations, the parameter types should be correctly inferred from the parent class definition.

---@class Buff
local mt = {}
---@type (fun(self: Buff, target: Buff): boolean)?
mt.on_cover = nil

---@class Buff.CommandAura : Buff
local tpl = {}
function tpl:on_cover(target)
    -- Expected: target type should be Buff
    return self.level > target.level
end

Actual Behaviour

The parameter types are inferred as any instead of the types defined in the parent class.

---@class Buff
local mt = {}
---@type (fun(self: Buff, target: Buff): boolean)?
mt.on_cover = nil

---@class Buff.CommandAura : Buff
local tpl = {}
function tpl:on_cover(target)
    -- Actual: target type is any ❌
    return self.level > target.level
end

This also affects @field declarations:

---@class Animal
---@field can_eat (fun(self: Animal, other: Animal): boolean)?
local base = {}

---@class Dog : Animal
local dog = {}
function dog:can_eat(other)
    -- Actual: other type is any ❌
    return true
end

Reproduction steps

1. Define a parent class with a method using @type or @field annotation
2. Create a child class that inherits from the parent
3. Override the method in the child class
4. Check the parameter types - they will be any instead of the parent's types

Additional Notes

This issue is related to #2569, but specifically focuses on field-style function declarations (@field and @type) rather than method declarations (function Class:method()).

PR #2859 successfully implemented type inference for method declaration style overrides, but did not cover field-style declarations.

Root cause: In script/vm/compiler.lua, the compileFunctionParam function only checks for 'doc.type.function' and 'function' node types, but @field nodes have type 'doc.field' with the actual function type stored in the extends property.

Log File

No response