Add git information to PD context

CHANGELOG.md

@@ -3,6 +3,11 @@ Note: This is in reverse chronological order, so newer entries are added to the
 Swift Next
 -----------
 
+* [#7202]
+
+  Package manifests can now access information about the Git repository the given package is in via the context object's 
+  `gitInformation` property. This allows to determine the current tag (if any), the current commit and whether or not there are uncommited changes.
+
 * [#7010]
 
   On macOS, `swift build` and `swift run` now produce binaries that allow backtraces in debug builds. Pass `SWIFT_BACKTRACE=enable=yes` environment variable to enable backtraces on such binaries when running them.

Package.swift

@@ -224,7 +224,8 @@ let package = Package(
             name: "PackageLoading",
             dependencies: [
                 "Basics",
-                "PackageModel"
+                "PackageModel",
+                "SourceControl",
             ],
             exclude: ["CMakeLists.txt", "README.md"]
         ),

Sources/PackageDescription/Context.swift

@@ -22,7 +22,19 @@ public struct Context {
     public static var packageDirectory : String {
         model.packageDirectory
     }
-
+
+    /// Information about the git status of a given package, if available.
+    @available(_PackageDescription, introduced: 5.11)
+    public static var gitInformation: GitInformation? {
+        model.gitInformation.map {
+            GitInformation(
+                currentTag: $0.currentTag,
+                currentCommit: $0.currentCommit,
+                hasUncommittedChanges: $0.hasUncommittedChanges
+            )
+        }
+    }
+
     /// Snapshot of the system environment variables.
     public static var environment : [String : String] {
         model.environment
@@ -31,3 +43,11 @@ public struct Context {
     private init() {
     }
 }
+
+/// Information about the git status of a given package, if available.
+@available(_PackageDescription, introduced: 5.11)
+public struct GitInformation {
+    public let currentTag: String?
+    public let currentCommit: String
+    public let hasUncommittedChanges: Bool
+}

Sources/PackageLoading/ContextModel.swift

@@ -18,14 +18,17 @@ import Foundation
 
 struct ContextModel {
     let packageDirectory : String
-
-    init(packageDirectory : String) {
-        self.packageDirectory = packageDirectory
-    }
+    let gitInformation: GitInformation?
 
     var environment : [String : String] {
         ProcessInfo.processInfo.environment
     }
+
+    struct GitInformation: Codable {
+        let currentTag: String?
+        let currentCommit: String
+        let hasUncommittedChanges: Bool
+    }
 }
 
 extension ContextModel : Codable {

Sources/PackageLoading/ManifestLoader.swift

@@ -15,6 +15,7 @@ import Basics
 import Dispatch
 import Foundation
 import PackageModel
+import SourceControl
 
 import class TSCBasic.BufferedOutputByteStream
 import struct TSCBasic.ByteString
@@ -958,7 +959,23 @@ public final class ManifestLoader: ManifestLoaderProtocol {
 
                         do {
                             let packageDirectory = manifestPath.parentDirectory.pathString
-                            let contextModel = ContextModel(packageDirectory: packageDirectory)
+
+                            let gitInformation: ContextModel.GitInformation?
+                            do {
+                                let repo = GitRepository(path: manifestPath.parentDirectory)
+                                gitInformation = ContextModel.GitInformation(
+                                    currentTag: repo.getCurrentTag(),
+                                    currentCommit: try repo.getCurrentRevision().identifier,
+                                    hasUncommittedChanges: repo.hasUncommittedChanges()
+                                )
+                            } catch {
+                                gitInformation = nil
+                            }
+
+                            let contextModel = ContextModel(
+                                packageDirectory: packageDirectory,
+                                gitInformation: gitInformation
+                            )
                             cmd += ["-context", try contextModel.encode()]
                         } catch {
                             return completion(.failure(error))

Sources/PackageModel/ToolsVersion.swift

@@ -31,6 +31,7 @@ public struct ToolsVersion: Equatable, Hashable, Codable, Sendable {
     public static let v5_8 = ToolsVersion(version: "5.8.0")
     public static let v5_9 = ToolsVersion(version: "5.9.0")
     public static let v5_10 = ToolsVersion(version: "5.10.0")
+    public static let v5_11 = ToolsVersion(version: "5.11.0")
     public static let vNext = ToolsVersion(version: "999.0.0")
 
     /// The current tools version in use.

Sources/SourceControl/GitRepository.swift

@@ -623,6 +623,17 @@ public final class GitRepository: Repository, WorkingCheckout {
         }
     }
 
+    public func getCurrentTag() -> String? {
+        self.lock.withLock {
+            try? callGit(
+                "describe",
+                "--exact-match",
+                "--tags",
+                failureMessage: "Couldn’t get current tag"
+            )
+        }
+    }
+
     public func checkout(tag: String) throws {
         // FIXME: Audit behavior with off-branch tags in remote repositories, we
         // may need to take a little more care here.

Tests/PackageLoadingTests/PD_5_11_LoadingTests.swift

@@ -0,0 +1,91 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift open source project
+//
+// Copyright (c) 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Basics
+import PackageModel
+import SourceControl
+import SPMTestSupport
+import XCTest
+
+class PackageDescription5_11LoadingTests: PackageDescriptionLoadingTests {
+    override var toolsVersion: ToolsVersion {
+        .v5_11
+    }
+
+    func testPackageContextGitStatus() throws {
+        let content = """
+                import PackageDescription
+                let package = Package(name: "\\(Context.gitInformation?.hasUncommittedChanges == true)")
+                """
+
+        try loadRootManifestWithBasicGitRepository(manifestContent: content) { manifest, observability in
+            XCTAssertNoDiagnostics(observability.diagnostics)
+            XCTAssertEqual(manifest.displayName, "true")
+        }
+    }
+
+    func testPackageContextGitTag() throws {
+        let content = """
+                import PackageDescription
+                let package = Package(name: "\\(Context.gitInformation?.currentTag ?? "")")
+                """
+
+        try loadRootManifestWithBasicGitRepository(manifestContent: content) { manifest, observability in
+            XCTAssertNoDiagnostics(observability.diagnostics)
+            XCTAssertEqual(manifest.displayName, "lunch")
+        }
+    }
+
+    func testPackageContextGitCommit() throws {
+        let content = """
+                import PackageDescription
+                let package = Package(name: "\\(Context.gitInformation?.currentCommit ?? "")")
+                """
+
+        try loadRootManifestWithBasicGitRepository(manifestContent: content) { manifest, observability in
+            XCTAssertNoDiagnostics(observability.diagnostics)
+
+            let repo = GitRepository(path: manifest.path.parentDirectory)
+            let currentRevision = try repo.getCurrentRevision()
+            XCTAssertEqual(manifest.displayName, currentRevision.identifier)
+        }
+    }
+
+    private func loadRootManifestWithBasicGitRepository(
+        manifestContent: String, 
+        validator: (Manifest, TestingObservability) throws -> ()
+    ) throws {
+        let observability = ObservabilitySystem.makeForTesting()
+
+        try testWithTemporaryDirectory { tmpdir in
+            let manifestPath = tmpdir.appending(component: Manifest.filename)
+            try localFileSystem.writeFileContents(manifestPath, string: manifestContent)
+            try localFileSystem.writeFileContents(tmpdir.appending("best.txt"), string: "best")
+
+            let repo = GitRepository(path: tmpdir)
+            try repo.create()
+            try repo.stage(file: manifestPath.pathString)
+            try repo.commit(message: "best")
+            try repo.tag(name: "lunch")
+
+            let manifest = try manifestLoader.load(
+                manifestPath: manifestPath,
+                packageKind: .root(tmpdir),
+                toolsVersion: self.toolsVersion,
+                fileSystem: localFileSystem,
+                observabilityScope: observability.topScope
+            )
+
+            try validator(manifest, observability)
+        }
+    }
+}