When compiling ArduinoJson within the Sloeber Arduino Eclipse Plugin, you may encounter the following error:

error: expected class-name before '{' token class memstream : public std::istream

You need to add the fuzzing/ folder to the “Source Folder Exclusion Patterns”, like on the picture bellow:

Source Folder Exclusion Patterns

See issues ArduinoJson #432 and Sloeber #642.