       var driver = try Driver(args: ["swiftc",
                                      "-I", cHeadersPath.nativePathString(escaped: true),
                                      "-I", swiftModuleInterfacesPath.nativePathString(escaped: true),
-                                     "-explicit-module-build",
+                                     "-explicit-module-build", "-v",
+                                     "-module-cache-path", moduleCachePath.nativePathString(escaped: true),
                                      "-working-directory", path.nativePathString(escaped: true),
                                      main.nativePathString(escaped: true)] + sdkArgumentsForTesting,
                               env: ProcessEnv.vars)

                                      path.nativePathString(escaped: true),
                                      "-emit-module",
                                      "-emit-module-path", moduleBarPath,
                                      srcBar.nativePathString(escaped: true),
                                      "-I", stdLibPath.nativePathString(escaped: true),
                                      "-I", shimsPath.nativePathString(escaped: true),

  func testModuleAliasingWithExplicitBuild() throws {
    try withTemporaryDirectory { path in
      try localFileSystem.changeCurrentWorkingDirectory(to: path)
      let moduleCachePath = path.appending(component: "ModuleCache")
      try localFileSystem.createDirectory(moduleCachePath)
      let srcBar = path.appending(component: "bar.swift")
      let moduleBarPath = path.appending(component: "Bar.swiftmodule").nativePathString(escaped: true)
      try localFileSystem.writeFileContents(srcBar) {
