set DYLD_LIBRARY_PATH if need

Sources/CartonCore/FoundationProcessEx.swift

@@ -71,12 +71,14 @@ extension Foundation.Process {
   public static func checkRun(
     _ executableURL: URL,
     arguments: [String],
+    environment: [String: String]? = nil,
     printsLoadingMessage: Bool = true,
     forwardExit: Bool = false
   ) throws {
     let process = Foundation.Process()
     process.executableURL = executableURL
     process.arguments = arguments
+    process.environment = environment
     try process.checkRun(
       printsLoadingMessage: printsLoadingMessage,
       forwardExit: forwardExit

Sources/CartonDriver/CartonDriverCommand.swift

@@ -135,19 +135,30 @@ func pluginSubcommand(subcommand: String, argv0: String, arguments: [String]) as
 
   let terminal = InteractiveWriter.stdout
   let toolchainSystem = try ToolchainSystem(fileSystem: localFileSystem)
-  let (swiftPath, _) = try await toolchainSystem.inferSwiftPath(terminal)
+  let swiftPath = try await toolchainSystem.inferSwiftPath(terminal)
   let extraArguments = arguments
 
-  let swiftExec = URL(fileURLWithPath: swiftPath.pathString)
+  let swiftExec = URL(fileURLWithPath: swiftPath.swift.pathString)
   let pluginArguments = try derivePackageCommandArguments(
     swiftExec: swiftExec,
     subcommand: subcommand,
     scratchPath: scratchPath.path,
     extraArguments: extraArguments
   )
 
+  var env: [String: String] = ProcessInfo.processInfo.environment
+  if ToolchainSystem.isSnapshotVersion(swiftPath.verison),
+     swiftPath.toolchain.extension == "xctoolchain"
+  {
+    env["DYLD_LIBRARY_PATH"] = swiftPath.toolchain.appending(
+      components: ["usr", "lib", "swift", "macosx"]
+    ).pathString
+  }
+
   try Foundation.Process.checkRun(
-    swiftExec, arguments: pluginArguments,
+    swiftExec, 
+    arguments: pluginArguments,
+    environment: env,
     forwardExit: true
   )
 }
@@ -175,9 +186,10 @@ public func main(arguments: [String]) async throws {
   case "package":
     let terminal = InteractiveWriter.stdout
     let toolchainSystem = try ToolchainSystem(fileSystem: localFileSystem)
-    let (swiftPath, _) = try await toolchainSystem.inferSwiftPath(terminal)
+    let swiftPath = try await toolchainSystem.inferSwiftPath(terminal)
+
     try Foundation.Process.checkRun(
-      URL(fileURLWithPath: swiftPath.pathString),
+      URL(fileURLWithPath: swiftPath.swift.pathString),
       arguments: ["package"] + arguments.dropFirst(),
       forwardExit: true
     )

Sources/CartonHelpers/DefaultToolchain.swift

@@ -12,7 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#if compiler(>=5.10)
+#if compiler(>=6.0)
+public let defaultToolchainVersion = "wasm-6.0-SNAPSHOT-2024-06-08-a"
+#elseif compiler(>=5.10)
 public let defaultToolchainVersion = "wasm-6.0-SNAPSHOT-2024-06-08-a"
 #else
 public let defaultToolchainVersion = "wasm-5.9.2-RELEASE"

Sources/SwiftToolchain/ToolchainManagement.swift

@@ -235,13 +235,19 @@ public class ToolchainSystem {
     }
   }
 
+  public struct SwiftPath {
+    public var verison: String
+    public var swift: AbsolutePath
+    public var toolchain: AbsolutePath
+  }
+
   /** Infer `swift` binary path matching a given version if any is present, or infer the
    version from the `.swift-version` file. If neither version is installed, download it.
    */
   public func inferSwiftPath(
     from versionSpec: String? = nil,
     _ terminal: InteractiveWriter
-  ) async throws -> (AbsolutePath, String) {
+  ) async throws -> SwiftPath {
     let specURL = versionSpec.flatMap { (string: String) -> Foundation.URL? in
       guard
         let url = Foundation.URL(string: string),
@@ -254,11 +260,9 @@ public class ToolchainSystem {
     let swiftVersion = try inferSwiftVersion(from: versionSpec, terminal)
 
     for resolver in resolvers {
-      if let path = try checkAndLog(
-        installationPath: resolver.toolchain(for: swiftVersion),
-        terminal
-      ) {
-        return (path, swiftVersion)
+      let toolchain = resolver.toolchain(for: swiftVersion)
+      if let path = try checkAndLog(installationPath: toolchain, terminal) {
+        return SwiftPath(verison: swiftVersion, swift: path, toolchain: toolchain)
       }
     }
 
@@ -291,7 +295,7 @@ public class ToolchainSystem {
       throw ToolchainError.invalidInstallationArchive(installationPath)
     }
 
-    return (path, swiftVersion)
+    return SwiftPath(verison: swiftVersion, swift: path, toolchain: installationPath)
   }
 
   public func fetchAllSwiftVersions() throws -> [String] {