How to make IntelliJ IDEA recognise code created by macros?

With the latest Scala plugin build, there is an API which can be used to write your own plugin to support your macros: http://blog.jetbrains.com/scala/2015/10/14/intellij-api-to-build-scala-macros-support/

Now, everyone can use this API to make their macros more friendly to their favorite IDE. To do that, you have to implement SyntheticMembersInjector, and register it in the plugin.xml file:

<extensions defaultExtensionNs="org.intellij.scala">
  <syntheticMemberInjector implementation="org.jetbrains.example.injector.Injector"/>
</extensions>