Building Groovy from Source

I experienced the following build failure concerning ant (version 1.7.0 compiled on September 23 2007) and ANTLR on Mac OS Leopard (10.5):

BUILD FAILED
/Users/jon_r/Documents/Projects/groovy-core/build.xml:65: Problem: failed to create task or type antlr
Cause: the class org.apache.tools.ant.taskdefs.optional.ANTLR was not found.
        This looks like one of Ant's optional components.
Action: Check that the appropriate optional JAR exists in
        -/usr/share/ant/lib
        -/Users/jon_r/.ant/lib
        -a directory added on the command line with the -lib argument

Do not panic, this is a common problem.
The commonest cause is a missing JAR.

This is not a bug; it is a configuration problem

This problem can be solved quickly by following these steps:

1. Determine which version of ant is running on your system
2. Download that version and untar the archive
3. Locate ant-antlr.jar in the lib directory
4. Copy the jar into either (as described in the above error message)
   • /usr/share/ant/lib
   • /Users/you/.ant/lib
   • A directory added on the command line with the -lib argument

After taking these steps your build should not fail with this error again. I hope someone else finds this information useful.

This page states that Ant >= 1.7.0 is required.

The build.xml only states

What's correct? We should sync this.