Set version info using info from the package context

.github/workflows/pull_request.yml

@@ -11,6 +11,9 @@ jobs:
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
     with:
       license_header_check_project_name: "gRPC"
+      # This is done by a similar job defined in soundness.yml. It needs to be
+      # separate in order to export an environment variable.
+      api_breakage_check_enabled: false
 
   grpc-soundness:
     name: Soundness

.github/workflows/soundness.yml

@@ -35,3 +35,28 @@ jobs:
       - name: Check generated code
         run: |
           ./dev/check-generated-code.sh
+
+  api-breakage-check:
+    name: API breakage check
+    runs-on: ubuntu-latest
+    container:
+      image: swift:latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+          fetch-depth: 0  # Fetching tags requires fetch-depth: 0 (https://github.com/actions/checkout/issues/1471)
+      - name: Mark the workspace as safe
+        # https://github.com/actions/checkout/issues/766
+        run: git config --global --add safe.directory ${GITHUB_WORKSPACE}
+      - name: Run API breakage check
+        shell: bash
+        # See package.swift for why we set GRPC_SWIFT_PROTOBUF_NO_VERSION=1
+        run: |
+          export GRPC_SWIFT_PROTOBUF_NO_VERSION=1
+
+          git fetch ${GITHUB_SERVER_URL}/${GITHUB_REPOSITORY} ${GITHUB_BASE_REF}:pull-base-ref
+          BASELINE_REF='pull-base-ref'
+          echo "Using baseline: $BASELINE_REF"
+          swift package diagnose-api-breaking-changes "$BASELINE_REF"

Package.swift

@@ -54,7 +54,7 @@ let defaultSwiftSettings: [SwiftSetting] = [
   .enableUpcomingFeature("MemberImportVisibility"),
 ]
 
-let targets: [Target] = [
+var targets: [Target] = [
   // protoc plugin for grpc-swift
   .executableTarget(
     name: "protoc-gen-grpc-swift",
@@ -143,6 +143,51 @@ let targets: [Target] = [
   ),
 ]
 
+// -------------------------------------------------------------------------------------------------
+
+extension Context {
+  fileprivate static var versionString: String {
+    guard let git = Self.gitInformation else { return "" }
+
+    if let tag = git.currentTag {
+      return tag
+    } else {
+      let suffix = git.hasUncommittedChanges ? " (modified)" : ""
+      return git.currentCommit + suffix
+    }
+  }
+
+  fileprivate static var buildCGRPCProtobuf: Bool {
+    let noVersion = Context.environment.keys.contains("GRPC_SWIFT_PROTOBUF_NO_VERSION")
+    return !noVersion
+  }
+}
+
+// Having a C module as a transitive dependency of a plugin seems to trip up the API breakage
+// checking tool. See also https://github.com/swiftlang/swift-package-manager/issues/8081
+//
+// The CGRPCProtobuf module (which only includes package version information) is conditionally
+// compiled and included based on an environment variable. This is set in CI only for the API
+// breakage checking job to avoid tripping up SwiftPM.
+if Context.buildCGRPCProtobuf {
+  targets.append(
+    .target(
+      name: "CGRPCProtobuf",
+      cSettings: [
+        .define("CGRPC_GRPC_SWIFT_PROTOBUF_VERSION", to: "\"\(Context.versionString)\"")
+      ]
+    )
+  )
+
+  for target in targets {
+    if target.name == "protoc-gen-grpc-swift" {
+      target.dependencies.append(.target(name: "CGRPCProtobuf"))
+    }
+  }
+}
+
+// -------------------------------------------------------------------------------------------------
+
 let package = Package(
   name: "grpc-swift-protobuf",
   platforms: [

Sources/CGRPCProtobuf/CGRPCProtobuf.c

@@ -0,0 +1,19 @@
+// Copyright 2025, gRPC Authors All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "CGRPCProtobuf.h"
+
+const char *cgrprc_grpc_swift_protobuf_version() {
+  return CGRPC_GRPC_SWIFT_PROTOBUF_VERSION;
+}

Sources/CGRPCProtobuf/include/CGRPCProtobuf.h

@@ -0,0 +1,20 @@
+// Copyright 2025, gRPC Authors All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef CGRPC_PROTOBUF_H_
+#define CGRPC_PROTOBUF_H_
+
+const char *cgrprc_grpc_swift_protobuf_version();
+
+#endif  // CGRPC_PROTOBUF_H_

Sources/protoc-gen-grpc-swift/Version.swift

@@ -14,26 +14,17 @@
  * limitations under the License.
  */
 
-internal enum Version {
-  /// The major version.
-  internal static let major = 1
-
-  /// The minor version.
-  internal static let minor = 0
-
-  /// The patch version.
-  internal static let patch = 0
-
-  /// Any additional label.
-  internal static let label = "development"
+#if canImport(CGRPCProtobuf)
+private import CGRPCProtobuf
+#endif
 
+internal enum Version {
   /// The version string.
   internal static var versionString: String {
-    let version = "\(Self.major).\(Self.minor).\(Self.patch)"
-    if Self.label.isEmpty {
-      return version
-    } else {
-      return version + "-" + Self.label
-    }
+    #if canImport(CGRPCProtobuf)
+    String(cString: cgrprc_grpc_swift_protobuf_version())
+    #else
+    "unknown"
+    #endif
   }
 }