Create a GitHub action to create a release

This should replace the script that I have locally to test swift-format for a release and at the same time expand the configurations that are being tested.

.github/workflows/create-release-commits.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+set -ex
+
+SWIFT_SYNTAX_TAG="$1"
+SWIFT_FORMAT_VERSION="$2"
+
+if [[ -z "$SWIFT_SYNTAX_TAG" || -z "$SWIFT_FORMAT_VERSION" ]]; then
+  echo "Update the Package manifest to reference a specific version of swift-syntax and embed the given version in the swift-format --version command"
+  echo "Usage create-release-commits.sh <SWIFT_SYNTAX_TAG> <SWIFT_FORMAT_VERSION>"
+  echo "  SWIFT_SYNTAX_TAG:     The tag of swift-syntax to depend on"
+  echo "  SWIFT_FORMAT_VERSION: The version of swift-format that is about to be released"
+  exit 1
+fi
+
+# Without this, we can't perform git operations in GitHub actions.
+git config --global --add safe.directory $(realpath .)
+
+git config --local user.name 'swift-ci'
+git config --local user.email '[email protected]'
+
+sed -E -i "s#branch: \"(main|release/[0-9]+\.[0-9]+)\"#from: \"$SWIFT_SYNTAX_TAG\"#" Package.swift
+git add Package.swift
+git commit -m "Change swift-syntax dependency to $SWIFT_SYNTAX_TAG"
+
+sed -E -i "s#print\(\".*\"\)#print\(\"$SWIFT_FORMAT_VERSION\"\)#" Sources/swift-format/PrintVersion.swift
+git add Sources/swift-format/PrintVersion.swift
+git commit -m "Change version to $SWIFT_FORMAT_VERSION"

.github/workflows/publish_release.yml

@@ -0,0 +1,108 @@
+name: Publish Release
+
+on:
+  workflow_dispatch:
+    inputs:
+      prerelease:
+        type: boolean
+        description: "Prerelease"
+        # Whether to create a prerelease or proper release
+        default: true
+        required: true
+      swift_format_version:
+        type: string
+        default: 601.0.0
+        description: "swift-format version"
+        # The version of swift-format to tag. If this is a prerelease, `-prerelease-<date>` is added to this version.
+        required: true
+      swift_syntax_tag:
+        type: string
+        default: 601.0.0
+        description: "swift-syntax version"
+        # The swift-syntax version to depend on. If this is a prerelease, the latest swift-syntax prerelease tag for this version is used.
+        required: true
+
+jobs:
+  check_triggering_actor:
+    name: Check user is allowed to create release
+    # Only a single user should be allowed to create releases to avoid two people triggering the creation of a release
+    # at the same time. If the release manager changes between users, update this condition.
+    runs-on: ubuntu-latest
+    steps:
+      - run: |
+          if [[ "${{ github.triggering_actor }}" != "ahoppen" ]]; then
+            echo "${{ github.triggering_actor }} is not allowed to create a release"
+            exit 1
+          fi
+  define_tags:
+    name: Determine dependent swift-syntax version and prerelease date
+    runs-on: ubuntu-latest
+    outputs:
+      swift_syntax_tag: ${{ steps.swift_syntax_tag.outputs.swift_syntax_tag }}
+      swift_format_version: ${{ steps.swift_format_version.outputs.swift_format_version }}
+    steps:
+    - name: Determine swift-syntax tag to depend on
+      id: swift_syntax_tag
+      shell: bash
+      run: |
+        if [[ "${{ github.event.inputs.prerelease }}" == "false" ]]; then
+          SWIFT_SYNTAX_TAG="${{ github.event.inputs.swift_syntax_tag }}"
+        else
+          git clone https://github.com/swiftlang/swift-syntax.git
+          cd swift-syntax
+          SWIFT_SYNTAX_TAG="$(git tag | grep ${{ github.event.inputs.swift_syntax_tag }}-prerelease | sort -r | head -1)"
+        fi
+
+        echo "Using swift-syntax tag: $SWIFT_SYNTAX_TAG"
+        echo "swift_syntax_tag=$SWIFT_SYNTAX_TAG" >> "$GITHUB_OUTPUT"
+    - name: Determine swift-format prerelease version
+      id: swift_format_version
+      run: |
+        if [[ "${{ github.event.inputs.prerelease }}" == "false" ]]; then
+          SWIFT_FORMAT_VERSION="${{ github.event.inputs.swift_format_version }}"
+        else
+          SWIFT_FORMAT_VERSION="${{ github.event.inputs.swift_format_version }}-prerelease-$(date +'%Y-%m-%d')"
+        fi
+        echo "Using swift-format version: $SWIFT_FORMAT_VERSION"
+        echo "swift_format_version=$SWIFT_FORMAT_VERSION" >> "$GITHUB_OUTPUT"
+  test_debug:
+    name: Test in Debug configuration
+    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
+    needs: define_tags
+    with:
+      pre_build_command: bash .github/workflows/create-release-commits.sh '${{ needs.define_tags.outputs.swift_syntax_tag }}' '${{ needs.define_tags.outputs.swift_format_version }}'
+      # We require that releases of swift-format build without warnings
+      build_command: swift test -Xswiftc -warnings-as-errors
+  test_release:
+    name: Test in Release configuration
+    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
+    needs: define_tags
+    with:
+      pre_build_command: bash .github/workflows/create-release-commits.sh '${{ needs.define_tags.outputs.swift_syntax_tag }}' '${{ needs.define_tags.outputs.swift_format_version }}'
+      # We require that releases of swift-format build without warnings
+      build_command: swift test -c release -Xswiftc -warnings-as-errors
+  create_tag:
+    name: Create Tag
+    runs-on: ubuntu-latest
+    needs: [check_triggering_actor, test_debug, test_release, define_tags]
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+    - name: Create release commits
+      run: bash .github/workflows/create-release-commits.sh '${{ needs.define_tags.outputs.swift_syntax_tag }}' '${{ needs.define_tags.outputs.swift_format_version }}'
+    - name: Tag release
+      run: |
+        git tag "${{ needs.define_tags.outputs.swift_format_version }}"
+        git push origin "${{ needs.define_tags.outputs.swift_format_version }}"
+    - name: Create release
+      env:
+        GH_TOKEN: ${{ github.token }}
+      run: |
+        if [[ "${{ github.event.inputs.prerelease }}" != "true" ]]; then
+          # Only create a release automatically for prereleases. For real releases, release notes should be crafted by hand.
+          exit
+        fi
+        gh release create "${{ needs.define_tags.outputs.swift_format_version }}" \
+          --title "${{ needs.define_tags.outputs.swift_format_version }}" \
+          --prerelease
+