This GitHub Action verifies compatibility of a Swift package with macros against all swift-syntax versions.

The introduction of macros in Swift 5.9 has significantly changed how many Swift libraries interact with swift-syntax. As pointed out by Point-Free in their article Being a good citizen in the land of SwiftSyntax this change has brought about several challenges:

1. Versioning Complexity: swift-syntax uses a versioning scheme where major versions correspond to minor versions of Swift (e.g., SwiftSyntax 509.0 corresponds to Swift 5.9). This complicates dependency management.

2. Breaking Changes: swift-syntax has had breaking changes in minor releases, which causes compatibility issues.

3. Dependency Resolution: With more libraries using swift-syntax for macros, there's an increased likelihood of unresolvable dependency graphs due to multiple libraries needing different major versions of the package.

This action aims to address these challenges by:

• Ensuring your macros are compatible with multiple versions of swift-syntax.
• Allowing you to easily test against both major versions and all minor versions.
• Helping you catch potential compatibility issues early in your development process.

By using this action, you're taking a step towards being a good citizen in the Swift ecosystem, helping to prevent dependency conflicts and ensuring your library works across a range of swift-syntax versions.

To use this action in your workflow, add the following step:

- name: Run Swift Macro Compatibility Check
  uses: Matejkob/swift-macro-compatibility-check@v1

jobs:
  check-macro-compatibility:
    runs-on: macos-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
      - name: Run Swift Macro Compatibility Check
        uses: Matejkob/swift-macro-compatibility-check@v1

The action tests against the following swift-syntax versions:

• 509.0.0
• 509.0.1
• 509.0.2
• 509.1.0
• 509.1.1
• 510.0.0
• 510.0.1
• 510.0.2
• 510.0.3
• 600.0.0
• 600.0.1

When major-versions-only is set to true, only versions 509.0.0, 510.0.0, and 600.0.0 are tested.

If you'd like to run the compatibility check script locally without GitHub Actions, you can do so by executing the provided bash script swift-macro-compatibility-check.sh in your terminal.

./swift-macro-compatibility-check.sh [--run-tests] [--major-versions-only] [--verbose]

The script checks the compatibility of a Swift package with multiple versions of swift-syntax. It can be configured to run tests and provide verbose output. The script performs the following steps for each version of swift-syntax:

1. Resolves package dependencies for the specific swift-syntax version.
2. Builds the Swift package.
3. Optionally runs tests.
4. Outputs a summary indicating which versions succeeded and which failed.

name: Swift Macro Compatibility

on: [push, pull_request]

jobs:
  check-compatibility:
    runs-on: macos-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
      - name: Run Swift Macro Compatibility Check
        uses: Matejkob/swift-macro-compatibility-check@v1

name: Swift Macro Compatibility

on: [push, pull_request]

jobs:
  check-compatibility:
    runs-on: macos-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
      - name: Run Swift Macro Compatibility Check
        uses: Matejkob/swift-macro-compatibility-check@v1
        with:
          run-tests: 'true'
          major-versions-only: 'false'
          verbose: 'true'

Contributions to improve the action or script are welcome. Please feel free to submit issues or pull requests.

This GitHub Action and the associated script are released under the MIT License.