Play! Framework, quick tip to overcome weird Eclipse errors

Quick tip to those working with Play! Framework in Eclipse (the following tip worked for Play! version 2.1.1 on Eclipse Helios SR2, but may very well apply for other versions). Sometimes Eclipse will complain about the index.render function, for example, claiming it cannot be resolved or the signature is incompatible, or whatever. While the overall project might not contain errors, the file in question will annoyingly enough display some errors (not warnings! errors!) that will try to drive you crazy. There might also be sudden problems in the build path of the project. Possible solutions that worked for me:
  1. Make sure you have the up-to-date Scale IDE installed (“Help -> Install New Software…” or “Help -> Check for Updates”). See also ScalaIDE’s Getting Started guide.
  2. Run play clean compile again from the console on the same project.
  3. Using “Project -> Clean…” didn’t really work. Instead, “Project -> Close Project” followed by “Project -> Open Project” did get rid of those annoying errors.