Implement SE-0219 Package Manager Dependency Mirroring

<rdar://problem/42511642> [SR-8328]: Implement SE-0219 Package Manager Dependency Mirroring
https://bugs.swift.org/browse/SR-8328

Author: aciidgh

Sources/Commands/SwiftPackageTool.swift

@@ -30,6 +30,30 @@ struct FetchDeprecatedDiagnostic: DiagnosticData {
     )
 }
 
+struct RequiredArgumentDiagnostic: DiagnosticData {
+    static let id = DiagnosticID(
+        type: RequiredArgumentDiagnostic.self,
+        name: "org.swift.diags.required-argument",
+        defaultBehavior: .error,
+        description: {
+            $0 <<< "missing required argument" <<< { "\($0.argument)" }
+        }
+    )
+
+    let argument: String
+}
+
+struct RequiredSubcommandDiagnostic: DiagnosticData {
+    static let id = DiagnosticID(
+        type: RequiredSubcommandDiagnostic.self,
+        name: "org.swift.diags.required-subcommand",
+        defaultBehavior: .error,
+        description: {
+            $0 <<< "missing required subcommand; use --help to list available subcommands"
+        }
+    )
+}
+
 /// swift-package tool namespace
 public class SwiftPackageTool: SwiftTool<PackageToolOptions> {
 
@@ -48,6 +72,51 @@ public class SwiftPackageTool: SwiftTool<PackageToolOptions> {
         case .version:
             print(Versioning.currentVersion.completeDisplayString)
 
+        case .config:
+            guard let configMode = options.configMode else {
+                diagnostics.emit(data: RequiredSubcommandDiagnostic())
+                return
+            }
+
+            let config = try getSwiftPMConfig()
+            try config.load()
+
+            switch configMode {
+            case .getMirror:
+                guard let packageURL = options.configOptions.packageURL else {
+                    diagnostics.emit(data: RequiredArgumentDiagnostic(argument: "--package-url"))
+                    return
+                }
+
+                if let mirror = config.getMirror(forURL: packageURL) {
+                    print(mirror)
+                } else {
+                    stderrStream <<< "not found\n"
+                    stderrStream.flush()
+                    executionStatus = .failure
+                }
+
+            case .unsetMirror:
+                guard let packageOrMirror = options.configOptions.packageURL ?? options.configOptions.mirrorURL else {
+                    diagnostics.emit(data: RequiredArgumentDiagnostic(argument: "--package-url or --mirror-url"))
+                    return
+                }
+
+                try config.unset(packageOrMirrorURL: packageOrMirror)
+
+            case .setMirror:
+                guard let packageURL = options.configOptions.packageURL else {
+                    diagnostics.emit(data: RequiredArgumentDiagnostic(argument: "--package-url"))
+                    return
+                }
+                guard let mirrorURL = options.configOptions.mirrorURL else {
+                    diagnostics.emit(data: RequiredArgumentDiagnostic(argument: "--mirror-url"))
+                    return
+                }
+
+                try config.set(mirrorURL: mirrorURL, forPackageURL: packageURL)
+            }
+
         case .initPackage:
             // FIXME: Error handling.
             let cwd = localFileSystem.currentWorkingDirectory!
@@ -347,6 +416,58 @@ public class SwiftPackageTool: SwiftTool<PackageToolOptions> {
                 usage: "Set tools version of package to the current tools version in use"),
             to: { if $1 { $0.toolsVersionMode = .setCurrent } })
 
+        // SwiftPM config subcommand.
+        let configParser = parser.add(
+            subparser: PackageMode.config.rawValue,
+            overview: "Manipulate configuration of the package")
+        binder.bind(parser: configParser,
+            to: { $0.configMode = PackageToolOptions.ConfigMode(rawValue: $1)! })
+
+        let setMirrorParser = configParser.add(
+            subparser: PackageToolOptions.ConfigMode.setMirror.rawValue,
+            overview: "Set a mirror for a dependency")
+
+        binder.bind(
+            setMirrorParser.add(
+                option: "--package-url", kind: String.self,
+                usage: "The package dependency url"),
+            setMirrorParser.add(
+                option: "--mirror-url", kind: String.self,
+                usage: "The mirror url"),
+            to: {
+                $0.configOptions.packageURL = $1
+                $0.configOptions.mirrorURL = $2
+            }
+        )
+
+        let unsetMirrorParser = configParser.add(
+            subparser: PackageToolOptions.ConfigMode.unsetMirror.rawValue,
+            overview: "Remove an existing mirror")
+        binder.bind(
+            unsetMirrorParser.add(
+                option: "--package-url", kind: String.self,
+                usage: "The package dependency url"),
+            unsetMirrorParser.add(
+                option: "--mirror-url", kind: String.self,
+                usage: "The mirror url"),
+            to: {
+                $0.configOptions.packageURL = $1
+                $0.configOptions.mirrorURL = $2
+            }
+        )
+
+        let getMirrorParser = configParser.add(
+            subparser: PackageToolOptions.ConfigMode.getMirror.rawValue,
+            overview: "Print mirror configuration for the given package dependency")
+        binder.bind(
+            option: getMirrorParser.add(
+                option: "--package-url", kind: String.self, usage: "The package dependency url"),
+            to: {
+                $0.configOptions.packageURL = $1
+            }
+        )
+
+        // Xcode project generation.
         let generateXcodeParser = parser.add(
             subparser: PackageMode.generateXcodeproj.rawValue,
             overview: "Generates an Xcode project")
@@ -482,10 +603,24 @@ public class PackageToolOptions: ToolOptions {
         case setCurrent
     }
     var toolsVersionMode: ToolsVersionMode = .display
+
+    enum ConfigMode: String {
+        case setMirror = "set-mirror"
+        case unsetMirror = "unset-mirror"
+        case getMirror = "get-mirror"
+    }
+    var configMode: ConfigMode?
+
+    struct ConfigOptions {
+        var packageURL: String?
+        var mirrorURL: String?
+    }
+    var configOptions = ConfigOptions()
 }
 
 public enum PackageMode: String, StringEnumArgument {
     case clean
+    case config
     case describe
     case dumpPackage = "dump-package"
     case edit
@@ -548,6 +683,12 @@ extension PackageToolOptions.CompletionToolMode: StringEnumArgument {
     }
 }
 
+extension PackageToolOptions.ConfigMode: StringEnumArgument {
+    static var completion: ShellCompletion {
+        return .none
+    }
+}
+
 extension SwiftPackageTool: ToolName {
     static var toolName: String {
         return "swift package"

Sources/Commands/SwiftTestTool.swift

@@ -54,11 +54,11 @@ struct NoMatchingTestsWarning: DiagnosticData {
     )
 }
 
-/// Diagnostic error when a command is run without its requeried command.
-struct RequiredArgumentDiagnostic: DiagnosticData {
+/// Diagnostic error when a command is run without its dependent command.
+struct DependentArgumentDiagnostic: DiagnosticData {
     static let id = DiagnosticID(
-        type: RequiredArgumentDiagnostic.self,
-        name: "org.swift.diags.required-argument",
+        type: DependentArgumentDiagnostic.self,
+        name: "org.swift.diags.dependent-argument",
         defaultBehavior: .error,
         description: {
             $0 <<< { "\($0.dependentArgument)" } <<< "must be used with" <<< { "\($0.requiredArgument)" }
@@ -423,7 +423,7 @@ public class SwiftTestTool: SwiftTool<TestToolOptions> {
             // The --num-worker option should be called with --parallel.
             guard options.mode == .runParallel else {
                 diagnostics.emit(
-                    data: RequiredArgumentDiagnostic(requiredArgument: "--parallel", dependentArgument: "--num-workers"))
+                    data: DependentArgumentDiagnostic(requiredArgument: "--parallel", dependentArgument: "--num-workers"))
                 throw Diagnostics.fatalError
             }
 

Sources/Commands/SwiftTool.swift

@@ -417,6 +417,17 @@ public class SwiftTool<Options: ToolOptions> {
         return try getPackageRoot().appending(component: "Package.resolved")
     }
 
+    func configFilePath() throws -> AbsolutePath {
+        return try getPackageRoot().appending(components: ".swiftpm", "config")
+    }
+
+    func getSwiftPMConfig() throws -> SwiftPMConfig {
+        return try _swiftpmConfig.dematerialize()
+    }
+    private lazy var _swiftpmConfig: Result<SwiftPMConfig, AnyError> = {
+        return Result(anyError: { SwiftPMConfig(path: try configFilePath()) })
+    }()
+
     /// Holds the currently active workspace.
     ///
     /// It is not initialized in init() because for some of the commands like package init , usage etc,
@@ -439,6 +450,7 @@ public class SwiftTool<Options: ToolOptions> {
             manifestLoader: try getManifestLoader(),
             toolsVersionLoader: ToolsVersionLoader(),
             delegate: delegate,
+            config: try getSwiftPMConfig(),
             repositoryProvider: provider,
             isResolverPrefetchingEnabled: options.shouldEnableResolverPrefetching,
             skipUpdate: options.skipDependencyUpdate

Sources/PackageGraph/PackageGraphLoader.swift

@@ -9,6 +9,7 @@
  */
 
 import Basic
+import SourceControl
 import PackageLoading
 import PackageModel
 import Utility
@@ -73,6 +74,7 @@ public struct PackageGraphLoader {
     /// Load the package graph for the given package path.
     public func load(
         root: PackageGraphRoot,
+        config: SwiftPMConfig = SwiftPMConfig(),
         externalManifests: [Manifest],
         diagnostics: DiagnosticsEngine,
         fileSystem: FileSystem = localFileSystem,
@@ -90,8 +92,9 @@ public struct PackageGraphLoader {
             externalManifests.map({ (PackageReference.computeIdentity(packageURL: $0.url), $0) })
         let manifestMap = Dictionary(uniqueKeysWithValues: manifestMapSequence)
         let successors: (Manifest) -> [Manifest] = { manifest in
-            manifest.dependencies.compactMap({ 
-                manifestMap[PackageReference.computeIdentity(packageURL: $0.url)] 
+            manifest.dependencies.compactMap({
+                let url = config.mirroredURL(forURL: $0.url)
+                return manifestMap[PackageReference.computeIdentity(packageURL: url)]
             })
         }
 
@@ -150,6 +153,7 @@ public struct PackageGraphLoader {
         // Resolve dependencies and create resolved packages.
         let resolvedPackages = createResolvedPackages(
             allManifests: allManifests,
+            config: config,
             manifestToPackage: manifestToPackage,
             rootManifestSet: rootManifestSet,
             diagnostics: diagnostics
@@ -205,6 +209,7 @@ private func checkAllDependenciesAreUsed(_ rootPackages: [ResolvedPackage], _ di
 /// Create resolved packages from the loaded packages.
 private func createResolvedPackages(
     allManifests: [Manifest],
+    config: SwiftPMConfig,
     manifestToPackage: [Manifest: Package],
     // FIXME: This shouldn't be needed once <rdar://problem/33693433> is fixed.
     rootManifestSet: Set<Manifest>,
@@ -232,7 +237,8 @@ private func createResolvedPackages(
 
         // Establish the manifest-declared package dependencies.
         packageBuilder.dependencies = package.manifest.dependencies.compactMap({
-            packageMap[PackageReference.computeIdentity(packageURL: $0.url)]
+            let url = config.mirroredURL(forURL: $0.url)
+            return packageMap[PackageReference.computeIdentity(packageURL: url)]
         })
 
         // Create target builders for each target in the package.

Sources/PackageGraph/RawPackageConstraints.swift

@@ -9,13 +9,15 @@
 */
 
 import PackageModel
+import SourceControl
 
 extension PackageDependencyDescription {
     /// Create the package reference object for the dependency.
-    public func createPackageRef() -> PackageReference {
+    public func createPackageRef(config: SwiftPMConfig) -> PackageReference {
+        let effectiveURL = config.mirroredURL(forURL: self.url)
         return PackageReference(
-            identity: PackageReference.computeIdentity(packageURL: url),
-            path: url,
+            identity: PackageReference.computeIdentity(packageURL: effectiveURL),
+            path: effectiveURL,
             isLocal: (requirement == .localPackage)
         )
     }
@@ -24,10 +26,10 @@ extension PackageDependencyDescription {
 extension Manifest {
 
     /// Constructs constraints of the dependencies in the raw package.
-    public func dependencyConstraints() -> [RepositoryPackageConstraint] {
+    public func dependencyConstraints(config: SwiftPMConfig) -> [RepositoryPackageConstraint] {
         return dependencies.map({
             return RepositoryPackageConstraint(
-                container: $0.createPackageRef(),
+                container: $0.createPackageRef(config: config),
                 requirement: $0.requirement.toConstraintRequirement())
         })
     }