Roslyn analyzer not loading in dotnet build

Question

tl/dr;

My project-referenced Roslyn analyzer works fine in Visual Studio 2019 but fails to load in dotnet build with the following build warning:

CSC : warning CS8032: An instance of analyzer Nearmap.CodeAnalysers.UseCtorInjection.UseCtorInjectionAnalyser cannot be created from [solution path]\MyCodeAnalysers\bin\Debug\netstandard2.0\MyCodeAnalysers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.4.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. The system cannot find the file specified.

Details

I have a Roslyn analyzer in a project which is loaded into the other projects in the solution.

The analyzer works as expected, and produces the expected warnings, during build in Visual Studio 2019.

When I try to build the solution from the command line (as our CI pipeline does) using dotnet build MySolution.sln I get the following build warning for every project that references the analyzer project:

CSC : warning CS8032: An instance of analyzer Nearmap.CodeAnalysers.UseCtorInjection.UseCtorInjectionAnalyser cannot be created from [solution path]\MyCodeAnalysers\bin\Debug\netstandard2.0\MyCodeAnalysers.dll : Could not load file or assembly 'Microsoft.CodeAnalysis, Version=4.4.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. The system cannot find the file specified.

where [solution path] is the full path to the folder containing the solution.

The analyzer project looks like this:

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

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework> 
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
    <!-- added in an attempt to fix the problem -->
    <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis" Version="4.4.0" />
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.3" />
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.4.0" />
  </ItemGroup>

</Project>

Projects reference this analyzer as:

  <ItemGroup>
    <ProjectReference Include="..\MyCodeAnalysers\MyCodeAnalysers.csproj"
                      PrivateAssets="all"
                      OutputItemType="Analyzer"
                      ReferenceOutputAssembly="false" />
  </ItemGroup>

I've checked the build output folder of the analyzer project and it contains all the DLL dependencies needed to load the analyzer, but it's obviously not being looked at when try to load the analyzer.

What am I missing?

Answer 1

The problem was the SDK version.

Aparently the Microsoft.CodeAnalysis.dll (and others) are loaded from the.Net SDK in use. We're currently still using the.Net 6.0 SDK to build our solutions. .Net 6.0 includes Microsoft.CodeAnalysis.dll 4.1.0 not the 4.4.0 version I was using. VS2019 runs the build differently, and didn't have the DLL resolution problem.

I fixed it by rolling the package references back to v4.1.0:

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis" Version="4.1.0" />
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.3" />
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.1.0" />
  </ItemGroup>