Invitation to F# Projects Maintainers: Join the Compiler Regression Testing Pilot #19126

We are establishing a regression testing pipeline that builds real-world OSS F# projects against every pull request to the F# compiler. We're looking for maintainers interested in participating in this pilot program.

Why Participate?

By contributing your project to this initiative, you gain an automated safeguard against compiler regressions. Your codebase will be compiled against proposed compiler changes before they are merged, meaning breaking changes affecting your project will be caught at the source rather than after release.

What We Need

We are particularly interested in projects that make extensive use of F# language features that are not necessarily exercised by the compiler itself:

• Deeply nested Computation expressions and custom builders, including resumable code
• Type providers - authoring as well as consumption
• Pushing Statically Resolved Type Parameters (SRTPs) to its limits
• Quotations and metaprogramming
• Queries
• Interfaces with static abstract methods (IWSAMs) consumption
• ...

Requirements

This is a pilot program, and we ask that participating projects meet the following criteria:

1. Stable build process — The project should build reliably with a single command (e.g., build.cmd, build.sh, or dotnet build). Flaky builds create noise and reduce the signal we're looking for.
2. Reproducible state — We pin to a specific commit SHA, so the build must succeed consistently at that point.
3. Binary log support — Ideally, your build command should produce MSBuild binary logs (.binlog files). This helps us diagnose issues efficiently when something fails. You can enable this by passing -bl to your build, e.g., dotnet build -bl:build.binlog.
4. Permissive for CI usage — The project's license should allow compilation in our public CI environment.

A Note on Patience

Depending on your project's setup, integrating it into our infrastructure may require some adjustments on our side. We are happy to work through any issues together — please don't hesitate to ask questions or flag problems in your PR. This is a learning process for us as well.

How to Get Involved

Submit a pull request to dotnet/fsharp that adds your project to the test matrix in azure-pipelines-PR.yml.

Locate the regression test section at the end of the file and add an entry to testMatrix:

- template: /eng/templates/regression-test-jobs. yml
  parameters:
    testMatrix:
    # Existing entry
    - repo: fsprojects/FSharpPlus
      commit: f614035b75922aba41ed6a36c2fc986a2171d2b8
      buildScript: build. cmd
      displayName: FSharpPlus_Windows

    # Add your project here
    - repo: your-org/your-project
      commit: abc123def456789...   # Full commit SHA
      buildScript: build. cmd       # Or build.sh, dotnet build, etc. 
      displayName: YourProject_Windows

Each entry requires:

• repo — GitHub repository in owner/name format
• commit — Full commit SHA (ensures reproducible builds)
• buildScript — Command to build the project
• displayName — Identifier for the CI job (use underscores, no spaces)

If your project needs to run on Linux, add a separate entry with useVmImage:

    - repo: your-org/your-project
      commit: abc123def456789... 
      buildScript: build.sh
      displayName: YourProject_Linux
      useVmImage: ubuntu-latest

This is a beta effort, and we welcome feedback on the process as we refine it.