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Remove MicrosoftCodeAnalysisVersion_LatestVS and unify analyzer dependencies #123641

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Copilot Jan 26, 2026
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Remove MicrosoftCodeAnalysisVersion_LatestVS and unify analyzer depen…
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Fix spelling: cadance -> cadence
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20 changes: 10 additions & 10 deletions eng/Versions.props
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<MicrosoftCodeAnalysisVersion_4_4>4.4.0</MicrosoftCodeAnalysisVersion_4_4>
<!-- Compatibility with VS 17.8/.NET SDK 8.0.1xx -->
<MicrosoftCodeAnalysisVersion_4_8>4.8.0</MicrosoftCodeAnalysisVersion_4_8>
<!-- Compatibility with the latest Visual Studio Preview release -->
<!--
The exact version is always a moving target. This version should never go ahead of the version of Roslyn that is included in the most recent
public Visual Studio preview version. If it were to go ahead, then any components depending on this version would not work in Visual Studio
and would cause a major regression for any local development that depends on those components contributing to the build.
This version must also not go ahead of the most recently release .NET SDK version, as that would break the source-build build.
Source-build builds the product with the most recent previously source-built release. Thankfully, these two requirements line up nicely
such that any version that satisfies the VS version requirement will also satisfy the .NET SDK version requirement because of how we ship.
Analyzers and source generators reference the latest Microsoft.CodeAnalysis version (MicrosoftCodeAnalysisVersion),
which is auto-updated via dependency flow. This version may move ahead of what's in the global.json SDK,
particularly when analyzers need to consume new Roslyn APIs. When that happens, update the bootstrap global.json
SDK to pull in the new Roslyn (similar to onboarding new language features).

Note: This version affects the design-time experience in VS, so moving ahead of the latest VS preview or SDK preview
can break local development. This is expected to happen occasionally as we move faster than previews to depend on
new analyzer features.
-->
<MicrosoftCodeAnalysisVersion_LatestVS>5.0.0-2.26070.104</MicrosoftCodeAnalysisVersion_LatestVS>
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@jjonescz jjonescz Jan 27, 2026 •
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It seems that previously you could have a situation where roslyn 5 was only available in VS 2026 but you wanted to allow devs to use also VS 2022 - then you could set RoslynLatestVS to 4.14 and that would work. Now you will effectively force devs to always use latest VS if I understand correctly.

If you instead want to just avoid binary breaks, you could build against latest roslyn only in CI, and still allow different (lower) version locally, I guess.

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@sbomer sbomer Jan 27, 2026

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I'm open to it, but personally prefer to keep CI and local dev in sync (based on bad experiences with them diverging).

I think it's not quite that bad - for example I tried loading+building LibraryImportGeneratorSample in VS 2022 with this change and it works. I think it only breaks if generators/analyzers adopt new analyzer APIs. This puts analyzer APIs in a similar situation as new language features.

Analyzers that need to support specific VS versions can also use pinned MicrosoftCodeAnalysisVersion_X_X versions.

@jkoritzinsky @stephentoub any thoughts/concerns?

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@jkoritzinsky jkoritzinsky Jan 28, 2026

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My concern is less people using VS2022 and more in the following scenario:

  1. Roslyn updates their assembly version to 5.1.0.
  2. That version flows to runtime.
  3. The generators in the runtime repo fail with the error "analyzer/generator assembly is referencing Roslyn 5.1.0 when the compiler version is 5.0.0", breaking the VS experience.

We can try with this change and adjust as needed, but I think to avoid serious breaks for the dev experience we'll need to have some way to use the Roslyn version that comes with the LKG sdk.

I don't believe we can just do a darc flow like our other dependencies as this dependency technically goes in the opposite direction of the build graph. For source-build, we effectively get the LKG behavior today because the version comes from the previously-source-built assets.

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@jjonescz jjonescz Jan 28, 2026 •
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I think it's not quite that bad - for example I tried loading+building LibraryImportGeneratorSample in VS 2022 with this change and it works. I think it only breaks if generators/analyzers adopt new analyzer APIs.

That is surprising to me (assuming your analyzer targets roslyn 5.* and your VS has roslyn 4.*), I think Roslyn forbids loading analyzers that target newer versions - we have a warning for that like this:

CSC : warning CS9057: The analyzer assembly '..\dotnet\sdk\8.0.200\Sdks\Microsoft.NET.Sdk.Razor\source- generators\Microsoft.CodeAnalysis.Razor.Compiler.SourceGenerators.dll' references version '4.9.0.0' of the compiler, which is newer than the currently running version '4.8.0.0'.

My concern is less people using VS2022 and more in the following scenario

That's the same failure mode, but yours is a better example, thanks.

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@sbomer sbomer Feb 2, 2026

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That is surprising to me (assuming your analyzer targets roslyn 5.* and your VS has roslyn 4.*)

Looks like that's because we set UsingToolMicrosoftNetCompilers, so VS 2022 uses the latest Roslyn to build. In the IDE I do see errors about partial methods missing implementations which suggest that the design-time build is not able to run the generator, but I don't see it surfacing as CS9057 and it doesn't block me from building the project.

Does that align with your expectations @jkoritzinsky @jjonescz @stephentoub? Is there a more serious break I'm missing?

For source-build, we effectively get the LKG behavior today because the version comes from the previously-source-built assets.

I think source build always sets UsingToolMicrosoftNetCompilers=false, and it doesn't use the LatestVS property, so it could get build breaks if MicrosoftCodeAnalysisVersion moves too far ahead of the bootstrap SDK. I think that's fine, as we would typically resolve it by updating the bootstrap SDK (and I'm suggesting we use the same strategy in dotnet/runtime).

Seem reasonable? I don't want to cause unnecessary breaks for local dev, but I think we need to prioritize shipping a consistent version here. Any objections to taking this change, and finding other mitigations for local dev when we hit problems? (For example, the workflow for using VS could have a way to override the version to use older Roslyn).

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@jjonescz jjonescz Feb 3, 2026

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Looks like that's because we set UsingToolMicrosoftNetCompilers, so VS 2022 uses the latest Roslyn to build.

Okay, that makes sense. (FWIW, since .NET 10, VS builds always use the roslyn from the SDK, so if you are using the toolset compiler for this reason, it isn't necessary anymore.)

In the IDE I do see errors about partial methods missing implementations

I guess that's the better case, but if there are other parts of the code that depend more heavily on the generated code, the IDE might become unusable.

<!-- Some of the analyzer dependencies used by ILLink project -->
<MicrosoftCodeAnalysisBannedApiAnalyzersVersion>3.3.5-beta1.23270.2</MicrosoftCodeAnalysisBannedApiAnalyzersVersion>
</PropertyGroup>

<!--
These packages affect the design-time experience in VS, so we update them at the same cadance as the MicrosoftCodeAnalysisVersion_LatestVS version.
These packages affect the design-time experience in VS, so we update them at the same cadence as the latest Microsoft.CodeAnalysis version.
-->
<PropertyGroup>
<MicrosoftCodeAnalysisCSharpCodeStyleVersion>$(MicrosoftCodeAnalysisVersion_LatestVS)</MicrosoftCodeAnalysisCSharpCodeStyleVersion>
<MicrosoftCodeAnalysisCSharpCodeStyleVersion>$(MicrosoftCodeAnalysisVersion)</MicrosoftCodeAnalysisCSharpCodeStyleVersion>
</PropertyGroup>

<PropertyGroup>
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2 changes: 1 addition & 1 deletion src/coreclr/tools/Directory.Build.props
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<!--
These packages affect the design-time experience in VS, we update them
at the same cadance as the MicrosoftCodeAnalysisVersion_LatestVS version.
at the same cadence as the latest Microsoft.CodeAnalysis version.
This property is set eng/Versions.props but we override it because the current
version 4.8.0 flags several warnings that need area-owner expertise to resolve.
TODO: https://github.com/dotnet/runtime/issues/91028.
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2 changes: 1 addition & 1 deletion src/libraries/Common/tests/Common.Tests.csproj
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</ItemGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>
<ItemGroup>
<ProjectReference Include="$(CommonTestPath)StreamConformanceTests\StreamConformanceTests.csproj" />
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2 changes: 1 addition & 1 deletion src/libraries/System.Private.CoreLib/gen/EventSourceGenerator.csproj
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</ItemGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" Version="$(MicrosoftCodeAnalysisVersion)" />
</ItemGroup>

</Project>
2 changes: 1 addition & 1 deletion src/libraries/System.Private.CoreLib/gen/System.Private.CoreLib.Generators.csproj
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</ItemGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" PrivateAssets="all" Version="$(MicrosoftCodeAnalysisVersion)" />
</ItemGroup>

</Project>
2 changes: 1 addition & 1 deletion .../System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSImportGenerator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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2 changes: 1 addition & 1 deletion ...ies/System.Runtime.InteropServices/gen/ComInterfaceGenerator/ComInterfaceGenerator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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2 changes: 1 addition & 1 deletion ...nteropServices/gen/DownlevelLibraryImportGenerator/DownlevelLibraryImportGenerator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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2 changes: 1 addition & 1 deletion ...s/System.Runtime.InteropServices/gen/LibraryImportGenerator/LibraryImportGenerator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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2 changes: 1 addition & 1 deletion ...Services/gen/Microsoft.Interop.SourceGeneration/Microsoft.Interop.SourceGeneration.csproj
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</ItemGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

</Project>
2 changes: 1 addition & 1 deletion ...raries/System.Text.RegularExpressions/gen/System.Text.RegularExpressions.Generator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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4 changes: 2 additions & 2 deletions src/tests/Common/XUnitWrapperGenerator/XUnitWrapperGenerator.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.CodeAnalysis" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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2 changes: 1 addition & 1 deletion src/tests/Common/external/external.csproj
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<PackageToInclude Include="Microsoft.DotNet.XUnitExtensions" />
<PackageToInclude Include="Microsoft.DotNet.XUnitAssert" />

<PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" />
<PackageReference Include="Microsoft.CodeAnalysis.Compilers" Version="$(MicrosoftCodeAnalysisVersion)" />
<PackageReference Include="CommandLineParser" Version="$(CommandLineParserVersion)" />
<PackageReference Include="Microsoft.Diagnostics.Tracing.TraceEvent" Version="$(TraceEventVersion)" />
<PackageReference Include="Newtonsoft.Json" Version="$(NewtonsoftJsonVersion)" />
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3 changes: 1 addition & 2 deletions src/tools/illink/src/ILLink.CodeFix/ILLink.CodeFixProvider.csproj
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</PropertyGroup>

<ItemGroup>
<PackageReference Condition="'$(DotNetBuildSourceOnly)' != 'true'" Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Condition="'$(DotNetBuildSourceOnly)' == 'true'" Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
</ItemGroup>

<ItemGroup>
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3 changes: 1 addition & 2 deletions src/tools/illink/src/ILLink.RoslynAnalyzer/ILLink.RoslynAnalyzer.csproj
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</ItemGroup>

<ItemGroup>
<PackageReference Condition="'$(DotNetBuildSourceOnly)' != 'true'" Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion_LatestVS)" PrivateAssets="all" />
<PackageReference Condition="'$(DotNetBuildSourceOnly)' == 'true'" Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
<PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisVersion)" PrivateAssets="all" />
<PackageReference Condition="'$(DotNetBuildSourceOnly)' != 'true'" Include="StaticCs" Version="$(StaticCsVersion)">
<PrivateAssets>all</PrivateAssets>
<ExcludeAssets>contentfiles</ExcludeAssets> <!-- We include our own copy of the ClosedAttribute to work in source build -->
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