     /// Swift parsers keyed by llbuild command name.
     private var swiftParsers: [String: SwiftCompilerOutputParser] = [:]
 
+    /// Buffer to accumulate non-swift output until command is finished
+    private var nonSwiftMessageBuffers: [String: [UInt8]] = [:]
+
     /// The build execution context.
     private let buildExecutionContext: BuildExecutionContext
 

        process: ProcessHandle,
        result: CommandExtendedResult
    ) {
        if result.result == .failed {
            // The command failed, so we queue up an asynchronous task to see if we have any error messages from the target to provide advice about.
            queue.async {

            swiftParser.parse(bytes: data)
        } else {
            queue.async {
                self.nonSwiftMessageBuffers[command.name, default: []] += data
            }
        }
    }
