How to compile Xtend + Java classes with Gradle

Question

I tyr to migrate a project that contains both Java and Xtend classes to Gradle. Unfortunately, I could not find any possibility to achieve an automated compilation of the Xtend part.

I am well aware of the Xtext Gradle Plugins (http://xtext.github.io/xtext-gradle-plugin/) that to my knowledge hook into the compile step of the Java plugin.

However, a CompileJava task cannot complete in the first place because of various referencing errors which are caused by missing Xtend classes (that are not yet generated...). In general, a suitable workflow should be

1. Compile Java and ignore errors
2. Compile Xtend
3. Compile Java again

To get it to work I need a way to compile Java and ignore errors without task failure for which I have not found any solution. And then I need to re-execute the compilation which I guess might require some other trick to bypass Gradle's up-to-date checking mechanism. Or am I fully mistaken?

Answer 1

The right sequence should be to first generate Xtend sources, and then compile everything. Just add the plugin and add new sourceSets as follows

plugins {
  id "org.xtext.xtend" version "1.0.0"
}

apply plugin: 'org.xtext.xtend'

sourceSets {
  main.xtendOutputDir = 'xtend-gen'
  test.xtendOutputDir = 'test/xtend-gen'
}

build should work afterwards.