Simplify Swift SDK installation/selection with aliases

Sources/CoreCommands/Options.swift

@@ -483,6 +483,12 @@ public struct BuildOptions: ParsableArguments {
     )
     public var swiftSDKSelector: String?
 
+    @Option(
+        name: .customLong("experimental-swift-sdk-alias"),
+        help: "Alias for a compatible Swift SDK to build with."
+    )
+    public var swiftSDKAlias: String?
+
     /// Which compile-time sanitizers should be enabled.
     @Option(
         name: .customLong("sanitize"),

Sources/CoreCommands/SwiftCommandState.swift

@@ -945,6 +945,13 @@ public final class SwiftCommandState {
                 outputHandler: { print($0.description) }
             )
 
+            let swiftSDKSelector = if let swiftSDKAliasString = self.options.build.swiftSDKAlias {
+                try SwiftToolchainVersion(toolchain: hostToolchain, fileSystem: self.fileSystem)
+                    .idForSwiftSDK(aliasString: swiftSDKAliasString)
+            } else {
+                self.options.build.swiftSDKSelector ?? self.options.build.deprecatedSwiftSDKSelector
+            }
+
             swiftSDK = try SwiftSDK.deriveTargetSwiftSDK(
                 hostSwiftSDK: hostSwiftSDK,
                 hostTriple: hostToolchain.targetTriple,
@@ -953,7 +960,7 @@ public final class SwiftCommandState {
                 customCompileTriple: self.options.build.customCompileTriple,
                 customCompileToolchain: self.options.build.customCompileToolchain,
                 customCompileSDK: self.options.build.customCompileSDK,
-                swiftSDKSelector: self.options.build.swiftSDKSelector ?? self.options.build.deprecatedSwiftSDKSelector,
+                swiftSDKSelector: swiftSDKSelector,
                 architectures: self.options.build.architectures,
                 store: store,
                 observabilityScope: self.observabilityScope,

Sources/PackageModel/CMakeLists.txt

@@ -53,9 +53,11 @@ add_library(PackageModel
   SupportedLanguageExtension.swift
   SwiftLanguageVersion.swift
   SwiftSDKs/SwiftSDK.swift
+  SwiftSDKs/SwiftSDKAlias.swift
   SwiftSDKs/SwiftSDKConfigurationStore.swift
   SwiftSDKs/SwiftSDKBundle.swift
   SwiftSDKs/SwiftSDKBundleStore.swift
+  SwiftToolchainVersion.swift
   Toolchain.swift
   ToolchainConfiguration.swift
   Toolchain+SupportedFeatures.swift

Sources/PackageModel/SwiftSDKs/SwiftSDKAlias.swift

@@ -0,0 +1,92 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift open source project
+//
+// Copyright (c) 2025 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
+//
+//===----------------------------------------------------------------------===//
+
+package struct SwiftSDKAlias {
+    init?(_ string: String) {
+        guard let kind = Kind(rawValue: string) else { return nil }
+        self.kind = kind
+    }
+
+    enum Kind: String, CaseIterable {
+        case staticLinux  = "static-linux"
+        case wasi         = "wasi"
+        case wasiEmbedded = "embedded-wasi"
+
+        var urlFileComponent: String {
+            switch self {
+            case .staticLinux, .wasi:
+                return self.rawValue
+            case .wasiEmbedded:
+                return Self.wasi.rawValue
+            }
+        }
+
+        var idComponent: String {
+            self.rawValue
+        }
+
+        var urlDirComponent: String {
+            switch self {
+            case .staticLinux:
+                "static-sdk"
+            case .wasi, .wasiEmbedded:
+                "wasi"
+            }
+        }
+    }
+
+    struct Version: CustomStringConvertible {
+        let rawValue = "0.0.1"
+
+        var description: String { self.rawValue }
+    }
+
+    let kind: Kind
+    let defaultVersion = Version()
+
+    var urlFileComponent: String {
+        "\(self.kind.urlFileComponent)-\(self.defaultVersion.rawValue)"
+    }
+}
+
+extension SwiftToolchainVersion {
+    package func urlForSwiftSDK(aliasString: String) throws -> String {
+        guard let swiftSDKAlias = SwiftSDKAlias(aliasString) else {
+            throw Error.unknownSwiftSDKAlias(aliasString)
+        }
+
+        return """
+        https://download.swift.org/\(
+            self.branch
+        )/\(
+            swiftSDKAlias.kind.urlDirComponent
+        )/\(
+            self.tag
+        )/\(
+            self.tag
+        )_\(swiftSDKAlias.urlFileComponent).artifactbundle.tar.gz
+        """
+    }
+
+    package func idForSwiftSDK(aliasString: String) throws -> String {
+        guard let swiftSDKAlias = SwiftSDKAlias(aliasString) else {
+            throw Error.unknownSwiftSDKAlias(aliasString)
+        }
+
+        switch swiftSDKAlias.kind {
+        case .staticLinux:
+            return "\(self.tag)_\(swiftSDKAlias.kind.idComponent)-\(swiftSDKAlias.defaultVersion)"
+        case .wasi, .wasiEmbedded:
+            return "\(self.tag.replacing("swift-", with: ""))-wasm32-\(swiftSDKAlias.kind.idComponent)"
+        }
+    }
+}

Sources/PackageModel/SwiftToolchainVersion.swift

@@ -0,0 +1,152 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift open source project
+//
+// Copyright (c) 2025 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 class Foundation.JSONDecoder
+import struct Foundation.URL
+
+package struct SwiftToolchainVersion: Equatable, Decodable {
+    package enum Error: Swift.Error, Equatable, CustomStringConvertible {
+        case versionMetadataNotFound(AbsolutePath)
+        case unknownSwiftSDKAlias(String)
+
+        package var description: String {
+            switch self {
+            case .versionMetadataNotFound(let absolutePath):
+                """
+                Toolchain version metadata file not found at path `\(absolutePath.pathString)`. \
+                Install a newer version of the Swift toolchain that includes this file.
+                """
+            case .unknownSwiftSDKAlias(let string):
+                """
+                Unknown alias for a Swift SDK: `\(string)`. Supported aliases: \(
+                    SwiftSDKAlias.Kind.allCases.map { "`\($0.rawValue)`" }.joined(separator: ", ")
+                ).
+                """
+            }
+        }
+    }
+
+    package init(
+        tag: String,
+        branch: String,
+        architecture: SwiftToolchainVersion.Architecture,
+        platform: SwiftToolchainVersion.Platform
+    ) {
+        self.tag = tag
+        self.branch = branch
+        self.architecture = architecture
+        self.platform = platform
+    }
+
+    /// Since triples don't encode the platform, we use platform identifiers
+    /// that match swift.org toolchain distribution names.
+    package enum Platform: String, Decodable {
+        case macOS
+        case ubuntu2004
+        case ubuntu2204
+        case ubuntu2404
+        case debian12
+        case amazonLinux2
+        case fedora39
+        case fedora41
+        case ubi9
+
+        var urlDirComponent: String {
+            switch self {
+            case .macOS:
+                "xcode"
+            case .ubuntu2004:
+                "ubuntu2004"
+            case .ubuntu2204:
+                "ubuntu2204"
+            case .ubuntu2404:
+                "ubuntu2404"
+            case .debian12:
+                "debian12"
+            case .amazonLinux2:
+                "amazonlinux2"
+            case .fedora39:
+                "fedora39"
+            case .fedora41:
+                "fedora41"
+            case .ubi9:
+                "ubi9"
+            }
+        }
+
+        var urlFileComponent: String {
+            switch self {
+            case .macOS:
+                "osx"
+            case .ubuntu2004:
+                "ubuntu20.04"
+            case .ubuntu2204:
+                "ubuntu22.04"
+            case .ubuntu2404:
+                "ubuntu24.04"
+            case .debian12:
+                "debian12"
+            case .amazonLinux2:
+                "amazonlinux2"
+            case .fedora39:
+                "fedora39"
+            case .fedora41:
+                "fedora41"
+            case .ubi9:
+                "ubi9"
+            }
+        }
+    }
+
+    package enum Architecture: String, Decodable {
+        case aarch64
+        case x86_64
+
+        var urlFileComponent: String {
+            switch self {
+            case .aarch64:
+                "-aarch64"
+            case .x86_64:
+                ""
+            }
+        }
+    }
+
+    /// A Git tag from which this toolchain was built.
+    package let tag: String
+
+    /// Branch from which this toolchain was built.
+    package let branch: String
+
+    /// CPU architecture on which this toolchain runs.
+    package let architecture: Architecture
+
+    /// Platform identifier on which this toolchain runs.
+    package let platform: Platform
+
+    package init(toolchain: some Toolchain, fileSystem: any FileSystem) throws {
+        let versionMetadataPath = try toolchain.swiftCompilerPath.parentDirectory.parentDirectory.appending(
+            RelativePath(validating: "lib/swift/version.json")
+        )
+        guard fileSystem.exists(versionMetadataPath) else {
+            throw Error.versionMetadataNotFound(versionMetadataPath)
+        }
+
+        self = try JSONDecoder().decode(
+            path: versionMetadataPath,
+            fileSystem: fileSystem,
+            as: Self.self
+        )
+    }
+}
+

Sources/SwiftSDKCommand/CMakeLists.txt

@@ -12,11 +12,11 @@ add_library(SwiftSDKCommand
   Configuration/ResetConfiguration.swift
   Configuration/SetConfiguration.swift
   Configuration/ShowConfiguration.swift
-  ConfigureSwiftSDK.swift
+  SwiftSDKConfigure.swift
   SwiftSDKSubcommand.swift
-  InstallSwiftSDK.swift
-  ListSwiftSDKs.swift
-  RemoveSwiftSDK.swift
+  SwiftSDKInstall.swift
+  SwiftSDKList.swift
+  SwiftSDKRemove.swift
   SwiftSDKCommand.swift)
 target_link_libraries(SwiftSDKCommand PUBLIC
   ArgumentParser

Sources/SwiftSDKCommand/SwiftSDKCommand.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift open source project
 //
-// Copyright (c) 2022-2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2022-2025 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
@@ -20,11 +20,11 @@ package struct SwiftSDKCommand: AsyncParsableCommand {
         abstract: "Perform operations on Swift SDKs.",
         version: SwiftVersion.current.completeDisplayString,
         subcommands: [
-            ConfigureSwiftSDK.self,
+            SwiftSDKConfigure.self,
             DeprecatedSwiftSDKConfigurationCommand.self,
-            InstallSwiftSDK.self,
-            ListSwiftSDKs.self,
-            RemoveSwiftSDK.self,
+            SwiftSDKInstall.self,
+            SwiftSDKList.self,
+            SwiftSDKRemove.self,
         ],
         helpNames: [.short, .long, .customLong("help", withSingleDash: true)]
     )

Sources/SwiftSDKCommand/ConfigureSwiftSDK.swift → Sources/SwiftSDKCommand/SwiftSDKConfigure.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift open source project
 //
-// Copyright (c) 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2023-2025 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
@@ -18,7 +18,7 @@ import PackageModel
 
 import var TSCBasic.stdoutStream
 
-struct ConfigureSwiftSDK: AsyncParsableCommand {
+struct SwiftSDKConfigure: AsyncParsableCommand {
     static let configuration = CommandConfiguration(
         commandName: "configure",
         abstract: """