.NET Standard 2.0类库引用ASP.NET Core NuGet包出现CS8032警告

我有一个基于.NET Standard 2.0的类库项目，引用版本2.2.0的Microsoft.AspNetCore和Microsoft.AspNetCore.Mvc NuGet包后，出现5条CS8032警告，提示无法加载以下类型：

• FixerWithFixAllAnalyzer
• DiagnosticAnalyzerFieldsAnalyzer
• DiagnosticDescriptorCreationAnalyzer
• CSharpRegisterActionAnalyzer
• ReportDiagnosticAnalyzer

警告示例 #

Warning CS8032  An instance of analyzer Microsoft.CodeAnalysis.CSharp.Analyzers.MetaAnalyzers.CSharpReportDiagnosticAnalyzer cannot be created from C:\\Program Files\\dotnet\\sdk\\NuGetFallbackFolder\\microsoft.codeanalysis.analyzers\\1.1.0\\analyzers\\dotnet\\cs\\Microsoft.CodeAnalysis.CSharp.Analyzers.dll: Could not load type 'Microsoft.CodeAnalysis.Analyzers.MetaAnalyzers.ReportDiagnosticAnalyzer`4' from assembly 'Microsoft.CodeAnalysis.Analyzers, Version=3.3.3.10305, Culture=neutral, PublicKeyToken=31bf3856ad364e35'..   MyLib (netstandard2.0)  C:\\Program Files\\dotnet\\sdk\\NuGetFallbackFolder\\microsoft.codeanalysis.analyzers\\1.1.0\\analyzers\\dotnet\\cs\\Microsoft.CodeAnalysis.CSharp.Analyzers.dll  1   Active  System.TypeLoadException: Could not load type 'Microsoft.CodeAnalysis.Analyzers.MetaAnalyzers.ReportDiagnosticAnalyzer`4' from assembly 'Microsoft.CodeAnalysis.Analyzers, Version=3.3.3.10305, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.
   at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type)
   at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase)
   at Microsoft.CodeAnalysis.Diagnostics.AnalyzerFileReference.Extensions`1.GetAnalyzersForTypeNames(Assembly analyzerAssembly, IEnumerable`1 analyzerTypeNames, Boolean& reportedError)

Severity    Code    Description Project File    Line    Suppression State   Detail Description
Warning CS8032  An instance of analyzer Microsoft.CodeAnalysis.CSharp.Analyzers.MetaAnalyzers.CSharpRegisterActionAnalyzer cannot be created from C:\\Program Files\\dotnet\\sdk\\NuGetFallbackFolder\\microsoft.codeanalysis.analyzers\\1.1.0\\analyzers\\dotnet\\cs\\Microsoft.CodeAnalysis.CSharp.Analyzers.dll: Method 'GetCodeBlockAnalyzer' in type 'Microsoft.CodeAnalysis.CSharp.Analyzers.MetaAnalyzers.CSharpRegisterActionAnalyzer' from assembly 'Microsoft.CodeAnalysis.CSharp.Analyzers, Version=1.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation..   MyLib (netstandard2.0)  C:\\Program Files\\dotnet\\sdk\\NuGetFallbackFolder\\microsoft.codeanalysis.analyzers\\1.1.0\\analyzers\\dotnet\\cs\\Microsoft.CodeAnalysis.CSharp.Analyzers.dll  1   Active  System.TypeLoadException: Method 'GetCodeBlockAnalyzer' in type 'Microsoft.CodeAnalysis.CSharp.Analyzers.MetaAnalyzers.CSharpRegisterActionAnalyzer' from assembly 'Microsoft.CodeAnalysis.CSharp.Analyzers, Version=1.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' does not have an implementation.
   at System.Reflection.RuntimeAssembly.GetType(RuntimeAssembly assembly, String name, Boolean throwOnError, Boolean ignoreCase, ObjectHandleOnStack type)
   at System.Reflection.RuntimeAssembly.GetType(String name, Boolean throwOnError, Boolean ignoreCase)
   at Microsoft.CodeAnalysis.Diagnostics.AnalyzerFileReference.Extensions`1.GetAnalyzersForTypeNames(Assembly analyzerAssembly, IEnumerable`1 analyzerTypeNames, Boolean& reportedError)

环境与已尝试操作 #

• 使用VS2022 17.4.4版本
• 已尝试删除所有bin/obj文件夹并重启VS，问题依旧

排查更新 #

清空项目所有文件，仅保留项目文件中以下配置：

<ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">    
    <PackageReference Include="Microsoft.AspNetCore" Version="2.2.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc" Version="2.2.0" />    
 </ItemGroup>

移除这些NuGet引用后警告消失，但引用时还会出现.NET Standard 2.0下的MVC相关警告（提示ASP.NET Core 2.2已终止支持）

方法1：禁用冲突的代码分析器 #

CS8032警告来自旧版本的Microsoft.CodeAnalysis.Analyzers（1.1.0）与项目依赖的新版本分析器组件不兼容。可以在项目文件中添加配置排除该旧分析器：

<ItemGroup>
  <Analyzer Remove="Microsoft.CodeAnalysis.Analyzers" Version="1.1.0" />
</ItemGroup>

或者彻底禁用默认分析器，仅保留项目需要的组件：

<PropertyGroup>
  <EnableDefaultAnalyzers>false</EnableDefaultAnalyzers>
</PropertyGroup>

方法2：升级NuGet包版本（推荐） #

.NET Standard 2.0兼容更高版本的ASP.NET Core包，建议将Microsoft.AspNetCore和Microsoft.AspNetCore.Mvc升级到2.2.x的最新补丁版本（2.2.8），或者直接升级到兼容.NET Standard 2.0的更高主版本（如3.1.x），既能解决组件版本冲突问题，也能避免终止支持的警告。

方法3：全局抑制CS8032警告 #

如果暂时无法升级或修改分析器配置，可以在项目文件中添加全局抑制规则：

<PropertyGroup>
  <NoWarn>$(NoWarn);CS8032</NoWarn>
</PropertyGroup>

内容的提问来源于stack exchange，提问作者buga