代码在Visual Studio中编译并运行,即使它具有未引用的类的名称

Question

我有一个我正在测试的ASP.NET核心Web应用程序,它不应该编译或运行,但它同时做到了.问题应该是我正在使用类名ActionResult- 来自未引用的程序集.注意如何ActionResult不是像解析的类名一样的蓝色,还要注意没有下划线的编译器错误:

此外,项目编译并运行得很好(虽然行为不如预期,当然,这是使用上面的值来响应对该URL的HTTP GET请求).到底是怎么回事？

这里的所有代码仅供参考:

Program.cs中:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace WebApplication2
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();
    }
}

Startup.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;

namespace WebApplication2
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "api/{Default}");
            });
        }
    }
}

DefaultController.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace WebApplication2.wwwroot
{
    [Route("api/[controller]")]
    [ApiController]
    public class DefaultController : ControllerBase
    {
        // GET: api/Default
        [HttpGet]
        public async Task<ActionResult<IEnumerable<string>>> Get()
        {
            return Task.FromResult(new string[] { "value1", "value2" });
        }
    }
}

这是VS和.NET信息:

Microsoft Visual Studio Professional 2017
版本15.9.4
VisualStudio.15.Release/15.9.4 + 28307.222
Microsoft .NET Core 2.1

Answer 1

ActionResult在Microsoft.AspNetCore.Mvc您实际引用的命名空间中.Visual Studio没有正确突出显示,这是我遇到的一个错误.