javac's Pretty class does not correctly handle enum constant declarations when the declaration involves use of a non-default constructor. The args to be passed to the constructor get hidden inside a comment, meaning that the actual code printed is incorrect and cannot be compiled.
Here's a test program:
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import java.io.*;
import javax.tools.JavaFileObject;
import javax.tools.StandardJavaFileManager;


import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.util.JavacTask;
import com.sun.tools.javac.api.JavacTool;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.Pretty;
public class Test {

    public static void main(String[] args) throws Exception {
        new Test().run(args);
    }

    void run(String... args) throws IOException {
        PrintWriter out = new PrintWriter(System.out);
        try {
            JavacTool tool = JavacTool.create();
            StandardJavaFileManager fm = tool.getStandardFileManager(null, null,
 null);

            Iterable<? extends JavaFileObject> files = fm.getJavaFileObjects(arg
s);

            JavacTask t = tool.getTask(null, fm, null, null, null, files);
            Iterable<? extends CompilationUnitTree> trees = t.parse();
            for (CompilationUnitTree tree: trees) {
                new Pretty(out, true).printExpr((JCTree) tree);
            }
        } finally {
            out.flush();
        }
    }
}
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Run it on this source:
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enum E {
    E1(1), E2(2), E3(3);
    E(int i) { }
}
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to get:
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enum E {
    /*public static final*/ E1 /* = new E(1) */,
    /*public static final*/ E2 /* = new E(2) */,
    /*public static final*/ E3 /* = new E(3) */;
    
    E(int i) {
    }
}
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Compiling that output gives the following, because of the incorrect code generated:
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error: cannot find symbol
symbol  : constructor E()
location: class E
1 error
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