Nested Table Type Narrowing

It would be super nice to be able to get field suggestions when narrowing an indice of a nested table.

Currently this:

---@class TestClass
---@field test_group_a TestGroupA
---@field test_group_b TestGroupB

---@class TestGroupA : TestGroupCommon
---@field test_field_1 string
---@field test_field_2 string

---@class TestGroupB : TestGroupCommon
---@field test_field_1 string
---@field test_field_3 string

---@class TestGroupCommon
---@field test_field_common string

---@type TestClass
local test_class

---@type 'test_group_a' | 'test_group_b'
local test_group

local test1 = test_class[test_group].test_field_1


---------------------------------------

---@alias TestTable {test_group_a: {test_field_1: string, test_field_2: string}, test_group_b: {test_field_1: string, test_field_3: string}}

---@type TestTable
local test_table

---@type "test_group_a" | "test_group_b"
local test_table_group

local test2 = test_table[test_table_group].test_field_1

The inferred type for test1 and test2 are both unknown. It would be nice if for test1 and test2 the inferred type would be string (as test_field_1 is a string for both, if test_field_1 and test_field_2 differed the inferred the type should be test_field_1_type | test_field_2_type). It would also be nice if on local test1 = test_class[test_group]. there were field suggestions for test_field_1 and test_field_common which are on both TestGroupA and TestGroupB.

Note: to add this for classes would also require doing: https://github.com/LuaLS/lua-language-server/issues/2217

まず、issue にある 2 つの Lua の例を再現し、インデックスアクセス、型の絞り込み、フィールド補完を処理する language-server のパスを調査します。完了条件は、両方の例で test_field_1 に対して string を推論し、可能性のあるネストされたテーブル型に共通するフィールドを提示できることです。その際、関連するクラスの絞り込みに関する issue 2217 も考慮します。