C# 中未定义或导入预定义类型“System.String”

Question

语境：

我在 Mac 上使用 Do.net-cli 和 Visual Studio Code 编码 C#。 这工作正常，直到几天前，每次我打开 Visual Studio Code 时，它都会给我数百万个关于“未定义或导入预定义类型‘System.String’”、“未定义或导入预定义类型‘System.Object’”的错误imported”，以及更多关于系统命名空间的错误。

题：

为什么会发生这种情况，我该如何解决？

我尝试过的事情：

1. 使用 do.net 清理项目（清理成功）
2. 使用 do.net 重建项目（构建成功）
3. 卸载并重新安装 c# 扩展

.vscode 文件：

任务.json：

{
    // See https://go.microsoft.com/fwlink/?LinkId=733558
    // for the documentation about the tasks.json format
    "version": "2.0.0",
    "tasks": [
        {
            "label": "build",
            "command": "dotnet",
            "type": "shell",
            "args": [
                "build",
                // Ask dotnet build to generate full paths for file names.
                "/property:GenerateFullPaths=true",
                // Do not generate summary otherwise it leads to duplicate errors in Problems panel
                "/consoleloggerparameters:NoSummary"
            ],
            "group": "build",
            "presentation": {
                "reveal": "silent"
            },
            "problemMatcher": "$msCompile"
        }
    ]
}

启动.json：

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": ".NET Core Launch (console)",
            "type": "coreclr",
            "request": "launch",
            "WARNING01": "*********************************************************************************",
            "WARNING02": "The C# extension was unable to automatically decode projects in the current",
            "WARNING03": "workspace to create a runnable launch.json file. A template launch.json file has",
            "WARNING04": "been created as a placeholder.",
            "WARNING05": "",
            "WARNING06": "If OmniSharp is currently unable to load your project, you can attempt to resolve",
            "WARNING07": "this by restoring any missing project dependencies (example: run 'dotnet restore')",
            "WARNING08": "and by fixing any reported errors from building the projects in your workspace.",
            "WARNING09": "If this allows OmniSharp to now load your project then --",
            "WARNING10": "  * Delete this file",
            "WARNING11": "  * Open the Visual Studio Code command palette (View->Command Palette)",
            "WARNING12": "  * run the command: '.NET: Generate Assets for Build and Debug'.",
            "WARNING13": "",
            "WARNING14": "If your project requires a more complex launch configuration, you may wish to delete",
            "WARNING15": "this configuration and pick a different template using the 'Add Configuration...'",
            "WARNING16": "button at the bottom of this file.",
            "WARNING17": "*********************************************************************************",
            "preLaunchTask": "build",
            "program": "${workspaceFolder}/bin/Debug/<insert-target-framework-here>/<insert-project-name-here>.dll",
            "args": [],
            "cwd": "${workspaceFolder}",
            "console": "internalConsole",
            "stopAtEntry": false
        },
        {
            "name": ".NET Core Attach",
            "type": "coreclr",
            "request": "attach",
            "processId": "${command:pickProcess}"
        }
    ]
}

Output 运行时：

调试控制台选项卡：

-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Private.CoreLib.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/Users/khaled/Projects/new/bin/Debug/netcoreapp3.1/new.dll'. Symbols loaded.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Diagnostics.Process.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.ComponentModel.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Console.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Runtime.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Threading.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded '/usr/local/share/dotnet/shared/Microsoft.NETCore.App/3.1.8/System.Text.Encoding.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Not Enough Args
The program '[82385] new.dll' has exited with code 0 (0x0).

.csproj 文件：

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.1</TargetFramework>
  </PropertyGroup>

</Project>

问题：

1. 在obj文件中，Debug.netcoreapp3.1,.NETCoreApp,Version=v3.1.AssemblyAttributes.cs和new.AssemblyInfo.cs
2. 程序文件
3. .csproj 文件

附加信息：

1. 程序运行成功

Answer 1

Omnisharp 需要 Mono 版本 > 6.4.0。 将 VSCode 设置中的Use Global Mono设置为always 。 如果这没有帮助，请尝试手动设置Mono Path以指向单声道的路径。

您在 OmniSharp 日志中有任何错误吗？ （在OUTPUT选项卡内）