当不存在Component时GetComponent返回值在编辑器与构建包中不一致

[ps5mh]

测试环境：xLua-v2.1.15, 官方Unity2019.4.40

测试代码：

using System;
using UnityEngine;
using XLua;

namespace XLuaTest
{
    public class Helloworld : MonoBehaviour
    {
        public Helloworld thiz;
        // Use this for initialization
        void Start()
        {
            var c = GetComponent<Canvas>();
            try
            {
                Debug.Log(c.enabled);
            }
            catch (MissingComponentException e)
            {
                // !! UNITY EDITOR ONLY !!
                // There is no 'Canvas' attached to the "Test" game object, but a script is trying to access it.
                // You probably need to add a Canvas to the game object "Test".Or your script needs to check if the component is attached before using it.
                Debug.LogError("In Edior:" + e);
            }
            catch (NullReferenceException e)
            {
                Debug.LogError("In Build:" + e);
            }
            LuaEnv luaenv = new LuaEnv();
            bool APPLYFIX = false; // my solution
            if (APPLYFIX)
            {
                luaenv.DoString(@"
local U = CS.UnityEngine;
if U.Application.isEditor then
    local function xlua_patch_member_func(type, funcName, genWrap)
        print('patch ' .. type.FullName .. ':' .. funcName)
        local r = debug.getregistry()
        local meta = r[type.FullName]
        -- @see xlua.c obj_indexer, upval1: instance indexer
        local _, objIndexer = debug.getupvalue(meta.__index, 1)
        objIndexer[funcName] = genWrap(objIndexer[funcName])
    end
    xlua_patch_member_func(typeof(U.GameObject), 'GetComponent', function(original)
        return function(...)
            local r = original(...)
            if r ~= nil and r:Equals(nil) then
                return nil
            end
            return r
        end
    end)
    xlua_patch_member_func(typeof(U.Object), 'GetComponent', function(original)
        return function(...)
            local r = original(...)
            if r ~= nil and r:Equals(nil) then
                return nil
            end
            return r
        end
    end)
end");
            }
            luaenv.DoString(@"
local U = CS.UnityEngine;
local go = U.GameObject.Find('Main Camera');
local c = go:GetComponent(typeof(U.Canvas)); -- go dees not have Canvas component
print(c == nil) -- print false in editor, true in build

c = go:AddComponent(typeof(U.Canvas));
print(c == nil) -- print false, definitely
U.GameObject.DestroyImmediate(c);
c = go:GetComponent(typeof(U.Canvas))
print(c == nil) -- print false in editor, true in build

local thiz = go:GetComponent(typeof(CS.XLuaTest.Helloworld));
U.GameObject.DestroyImmediate(thiz);
print(thiz.thiz == nil) -- print false, it's ok, destroyed, but valid userdata object
");
            luaenv.Dispose();
        }
    }
}

执行结果：

编辑器中打印false， 构建包中打印true

[chexiongsheng]

感觉这是unity的处理不一样导致的。
lua那是nil，代表真的返回了一个c#的null了。
不是nil代表返回一个c#对象。c#那只是通过操作符重载让它像null。

[ps5mh]

是的，后来我看了Unity引擎的代码，又提交了一个PR尝试修复此问题