 
         let generatedModuleMapDir = "$(OBJROOT)/GeneratedModuleMaps/$(PLATFORM_NAME)"
         let moduleMapFile = "\(generatedModuleMapDir)/\(target.name).modulemap"
-        let moduleMapFileContents: String
+        let moduleMapFileContents: String?
 
         if let clangTarget = target.underlyingTarget as? ClangTarget {
             // Let the target itself find its own headers.

            fatalError("unexpected target")
        }

        settings[.MODULEMAP_PATH] = moduleMapFile
        settings[.MODULEMAP_FILE_CONTENTS] = moduleMapFileContents

        // Pass the path of the module map up to all direct and indirect clients.
        impartedSettings[.OTHER_CFLAGS, default: ["$(inherited)"]].append("-fmodule-map-file=\(moduleMapFile)")


            // Also propagate this search path to all direct and indirect clients.
            impartedSettings[.HEADER_SEARCH_PATHS, default: ["$(inherited)"]].append(clangTarget.includeDir.pathString)

            if !fileSystem.exists(clangTarget.moduleMapPath) {
                impartedSettings[.OTHER_SWIFT_FLAGS, default: ["$(inherited)"]] +=
                    ["-Xcc", "-fmodule-map-file=\(moduleMapFile)"]

                moduleMapFileContents = """
                    module \(target.c99name) {
                        umbrella "\(clangTarget.includeDir.pathString)"
                        export *
                    }
                    """
            } else {
                moduleMapFileContents = nil
            }
        } else if let swiftTarget = target.underlyingTarget as? SwiftTarget {
            settings[.SWIFT_VERSION] = swiftTarget.swiftVersion.description
            // Generate ObjC compatibility header for Swift library targets.
