Update Roslyn Version

This skill describes how to update the Roslyn language server version in the vscode-csharp repository.

Prerequisites

1. You must have a local clone of the dotnet/roslyn repository (commonly at C:\Users\<username>\source\repos\roslyn)
2. The roslyn-tools CLI tool must be installed as a global .NET tool:

   dotnet tool install -g Microsoft.RoslynTools --prerelease --add-source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json
   

   Note: After installation, the tool is invoked as roslyn-tools (not dotnet roslyn-tools)
3. You must have authenticated with GitHub for roslyn-tools:

   roslyn-tools authenticate
   

Input Required

• New Roslyn Version: The new version to update to (e.g., 5.5.0-2.26080.10)

Process

Step 1: Create a New Branch

Create a new git branch for the update:

git checkout -B update/roslyn-<version>

Replace <version> with the new Roslyn version, using dashes instead of dots for the branch name.

Step 2: Update package.json

Update the defaults.roslyn field in package.json:

"defaults": {
    "roslyn": "<new-version>",
    ...
}

Step 3: Run updateRoslynVersion

This step acquires the new Roslyn packages and ensures they are in the proper feeds:

npm run updateRoslynVersion

This task:

• Downloads all platform-specific Roslyn nuget packages
• Ensures packages are saved to the consumption AzDo artifacts feed
• Runs installDependencies to update local dependencies

Note: You may need to install the Azure Artifacts NuGet Credential Provider for interactive authentication.

Step 4: Get the Previous Roslyn Commit SHA

The commit SHAs are stored in the .nuspec files inside the downloaded NuGet packages. After running npm run updateRoslynVersion, the new version's package will be cached locally, but you need to explicitly download the old version to get its commit SHA.

To get the old version's commit SHA:

1. First, find the old version number from the current package.json (before your edit) - look at the defaults.roslyn value
2. Download the old version's package to the local cache:

   dotnet restore "C:\Users\<username>\source\repos\vscode-csharp\msbuild\server" /p:PackageName=roslyn-language-server.osx-arm64 /p:PackageVersion=<old-version> --interactive
   

3. Extract the commit SHA from the nuspec file:

   Get-Content "C:\Users\<username>\source\repos\vscode-csharp\out\.nuget\roslyn-language-server.osx-arm64\<old-version>\roslyn-language-server.osx-arm64.nuspec" | Select-String -Pattern "commit"
   

   This will show output like:

   <repository type="git" url="https://github.com/dotnet/roslyn" branch="main" commit="0e21a3cb684db6ab02646541a780b3278f53d19e" />
   

Step 5: Get the New Roslyn Commit SHA

After running npm run updateRoslynVersion, the new version's package is already cached. Extract the commit SHA:

Get-Content "C:\Users\<username>\source\repos\vscode-csharp\out\.nuget\roslyn-language-server.osx-arm64\<new-version>\roslyn-language-server.osx-arm64.nuspec" | Select-String -Pattern "commit"

Note: The Azure DevOps artifacts feed web pages require authentication and may not load properly in automated scenarios. Always use the nuspec files from the local package cache.

Step 6: Generate Changelog Entries Using PR Finder

First, locate the local dotnet/roslyn repository. Common locations include:

• C:\Users\<username>\source\repos\roslyn
• C:\repos\roslyn

Navigate to the roslyn repository, fetch the latest, and run the pr-finder tool:

cd <path-to-roslyn-repo>
git fetch origin
roslyn-tools pr-finder --start <old-commit-sha> --end <new-commit-sha> --format "o#"

Important: The tool is invoked as roslyn-tools (a global tool), NOT dotnet roslyn-tools.

This will output a list of PRs in the format needed for the changelog:

  * <PR title> (PR: [#<number>](https://github.com/dotnet/roslyn/pull/<number>))

Step 7: Update CHANGELOG.md

Add an entry to CHANGELOG.md under the current version section (e.g., # 2.121.x): Copy the results from the previous step (should already be formatted correctly).

* Update Roslyn to <new-version> (PR: [#](https://github.com/dotnet/vscode-csharp/pull/))
  * <PR title 1> (PR: [#<number>](https://github.com/dotnet/roslyn/pull/<number>))
  * <PR title 2> (PR: [#<number>](https://github.com/dotnet/roslyn/pull/<number>))
  ...

Note: Leave the PR number blank initially (just [#]) - it will be updated after the PR is created.

Step 8: Filter Changelog Entries

Review the changelog entries and remove any PRs that obviously don't affect VS Code. Remove entries that are:

• Infrastructure/Build changes: CI/CD pipelines, build scripts, Azure DevOps configurations
• Visual Studio-only changes: Features or fixes specific to Visual Studio IDE (not VS Code)
• Test-only changes: Test infrastructure, test fixes that don't affect production code
• Internal tooling: Changes to internal tools not used by the language server
• Documentation-only: README updates, internal docs (unless they document user-facing features)

Keep entries that are:

• Language server protocol (LSP) changes
• Code analysis/diagnostics improvements
• Completion, navigation, refactoring features
• Performance improvements
• Bug fixes that affect language server behavior
• API changes that could affect VS Code extension

Step 9: Commit and Push

git add package.json CHANGELOG.md
git commit -m "Update Roslyn to <new-version>"
git push -u origin update/roslyn-<version>

Step 10: Create Pull Request

Create a pull request on GitHub:

• Title: Update roslyn to <new-version>
• Base: main

Step 11: Update Changelog with PR Number

After the PR is created, note the PR number (e.g., #8941), then:

1. Update the CHANGELOG.md entry to include the actual PR number:

   * Update Roslyn to <new-version> (PR: [#8941](https://github.com/dotnet/vscode-csharp/pull/8941))
   

2. Commit and push the update:

   git add CHANGELOG.md
   git commit -m "Update changelog with PR number"
   git push
   

Example

For updating from 5.4.0-2.26077.7 to 5.5.0-2.26080.10:

1. Branch: update/roslyn-5-5-0-2-26080-10
2. package.json change: "roslyn": "5.5.0-2.26080.10"
3. Find old commit from package metadata for version 5.4.0-2.26077.7
4. Find new commit from package metadata for version 5.5.0-2.26080.10
5. Run pr-finder in roslyn repo
6. Update CHANGELOG.md with the output
7. Run npm run updateRoslynVersion
8. Create PR titled "Update roslyn to 5.5.0-2.26080.10"
9. Update changelog with PR number

Reference PR

See PR #8941 as an example of a Roslyn version update.

Files Modified

• package.json - Update defaults.roslyn version
• CHANGELOG.md - Add changelog entry with Roslyn PR list

Troubleshooting

Authentication Issues with updateRoslynVersion

If you encounter authentication errors:

1. Install Azure Artifacts Credential Provider
2. Run the command again - it should prompt for interactive authentication

pr-finder Returns Empty Results

Ensure:

1. You have fetched the latest from origin in the roslyn repo: git fetch origin
2. Both commit SHAs exist in your local repo
3. You have authenticated with roslyn-tools authenticate
4. You are invoking the tool correctly as roslyn-tools pr-finder (not dotnet roslyn-tools)

Finding Commit SHAs

The commit SHAs are embedded in the nuspec files inside the downloaded NuGet packages:

1. After running npm run updateRoslynVersion, packages are cached in out/.nuget/
2. To get the old version's commit, you may need to explicitly download it first:

   dotnet restore "msbuild\server" /p:PackageName=roslyn-language-server.osx-arm64 /p:PackageVersion=<old-version> --interactive
   

3. Then read the nuspec file:

   Get-Content "out\.nuget\roslyn-language-server.osx-arm64\<version>\roslyn-language-server.osx-arm64.nuspec" | Select-String -Pattern "commit"
   

Note: The Azure DevOps artifacts feed web pages require authentication and often fail to load in automated scenarios. Always use the local nuspec files instead.