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How to modify the AST using Java 9+ [duplicate]

This question already has answers here:
Accessing com.sun.tools.javac.util from Java 9
(2 answers)
Closed 3 years ago.
I've been trying to modify the AST using annotation processors. I tried extending Lombok, but that seemed too hard, so I decided to use things from com.sun.source.* and com.sun.tools.javac.* However, I am using java 11, and the document I was learning from, "The Hacker's Guide to Javac" http://scg.unibe.ch/archive/projects/Erni08b.pdf, uses Java 6. The api they used is now internal and my module cannot read it.
In IntelliJ, it gave me a few errors, but I clicked on the suggestions (which said things like "Add --Xxx-xxx to xxx" without paying attention to them. When I tried compiling with Maven, it failed, since the module does not read the internals of jdk.compiler.
These are some of my imports:
import com.sun.source.util.Trees;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.TreeMaker;
import com.sun.tools.javac.tree.TreeTranslator;
import com.sun.tools.javac.util.Context;
My module-info file contains
requires jdk.compiler;
requires java.compiler;
I got messages like "[ERROR]package com.sun.tools.javac.util is declared in module jdk.compiler, which does not export it to module OtherAnnot" and "[ERROR] (package com.sun.tools.javac.tree is declared in module jdk.compiler, which does not export it to module OtherAnnot)"
Edit: I guess this is a duplicate, but I wanted to know if there was some alternative API for AST transformations in java 9.

With the introduction of Project Jigsaw, the JDK has been modularized, allowing users to create their own modules as well. These modules allows you to export packages of yours, allowing programs that require your module (in their module-info.java) to use the exported packages.
Ideally, you'd be prohibited from using classes that reside in packages that are not exported. However, to not break backwards compatibility, VM flags were introduced that allow you to forcefully export packages (that don't belong to you) to your module.
Given your error message, the respective VM flag to add is:
--add-exports jdk.compiler/com.sun.tools.javac.tree=OtherAnnot
The pattern here is:
--add-exports THEIR_MODULE/THEIR_PACKAGE=YOUR_MODULE
If the compiler complains that packages aren't exported to the unnamed module, then you can use the following:
--add-exports THEIR_MODULE/THEIR_PACKAGE=ALL-UNNAMED

Using JCodeModel, SonarLint reports classes from "sun.*" packages should not be used

I am trying to use com.sun.codemodel.JCodeModel in some code that is generating Java Pojo classes from JSON schemas but SonarLint is reporting that classes from "sun.*" packages should not be used. Is there any replacement for JCodeModel in a different package that is compliant?

Although this other thread link says that you shouldn't restrictedly believe in Sonar evaluation, I found this option that you should consider: Apache JAXBUtils

Where has sun.misc.Perf moved now that tools.jar was decomposed in Java 9

sun.misc.Perf was in tools.jar and in Java 9 this was removed and restructured based on the modules concept, so the question is how do you access it in newer Java?
I need to know which module now contains this code.

The implementation has been moved under the jdk.internal.perf package within the java.base module.
As the name already suggests, the package has not been exported from the module and hence if you still want to explicitly make use of the classes within this package, you can make use of the VM option:
--add-exports java.base/jdk.internal.perf=<your-module-name>
Do note though, this is an unreliable way of making use of such classes and a better solution would always be to migrate for the specific use cases without depending on the (internal) sun.misc.* classes.

Replace a class within the Java class library with a custom version

The class BasicLabelUI in javax/swing/plaf/basic is affected by a confirmed bug.
In my application I need functionality provided by the fixed version (filed for v9).
Due to both legal and technical reasons, I'm still bound to the affected JDK version.
My approach was to create a package javax/swing/plaf/basic inside my project, containing the fixed version.
How can I force my project to favor my included version of the class over the defective class in the installed JDK?
This has to be somewhat portable as the fixed class also has to be working on customer side and the defective class in the JDK installation has to be disregarded. Therefore, I dont want to modify the JDK, but rather bypass this particular class.

As mentioned by the other answers, you could in theory of course unzip your JVM's rt.jar file and replace the file with a compatible bugfixed version.
Any classes of the Java Class library such as those of Swing are loaded by the bootstrap class loader which looks up its classes from this rt.jar. You can generally not prepend classes to this classpath without adding them to this file. There is a (non-standard) VM option
-Xbootclasspath/jarWithPatchedClass.jar:path
where you would prepend a jar file that includes the patched version, but this does not necessarily work on any Java virtual machine. Also, it is illegal to deploy an application that changes this hehavior! As it is stated in the official documentation:
Do not deploy applications that use this option to override a class in
rt.jar because this violates the Java Runtime Environment binary code
license.
If you however appended a class to the bootstrap class loader (what is possible without using non-standard APIs by using the instrumentation API), the runtime would still load the original class as the bootstrap class loader in this case searches the rt.jar first. It is therefore impossible to "shadow" the broken class without modifying this file.
Finally, it is always illegal to distribute a VM with a patched file, i.e. putting it into a production system for a customer. The license agreement states clearly that you need to
[...] distribute the [Java runtime] complete and unmodified and only bundled as part of your applets and applications
Changing the VM that you distribute is therefore not recommended as you might face legal consequences when this is ever uncovered.
Of course, you can in theory build your own version of the OpenJDK but you could not call the binary Java anymore when you distribute it and I assume that your customer would not allow for this by what you suggest in your answer. By experience, many secure environments compute hashes of binaries before execution what would prohibit both approaches of tweaking the executing VM.
The easiest solution for you would probably be the creation of a Java agent that you you add to your VM process on startup. In the end, this is very similar to adding a library as a class path dependency:
java -javaagent:bugFixAgent.jar -jar myApp.jar
A Java agent is capable of replacing a class's binary representation when the application is started and can therefore change the implementation of the buggy method.
In your case, an agent would look something like the following where you need to include the patched class file as a ressource:
public static class BugFixAgent {
public static void premain(String args, Instrumentation inst) {
inst.addClassFileTransformer(new ClassFileTransformer() {
#Override
public byte[] transform(ClassLoader loader,
String className,
Class<?> classBeingRedefined,
ProtectionDomain protectionDomain,
byte[] classfileBuffer) {
if (className.equals("javax/swing/plaf/basic/BasicLabelUI")) {
return patchedClassFile; // as found in the repository
// Consider removing the transformer for future class loading
} else {
return null; // skips instrumentation for other classes
}
}
});
}
}
The javadoc java.lang.instrumentation package offers a detail description of how to build and implement a Java agent. Using this approach, you can use the fixed version of the class in question without breaking the license agreement.
From experience, Java agents are a great way for fixing temporary bugs in third party libraries and in the Java Class Library without needing to deploy changes in your code or even being required to deploy a new version for a customer. As a matter of fact, this is a typical use case for using a Java agent.

How can I force my project to favor my included version of the class over the defective class in the installed JDK?
Simple answer - you can't. At least, not while strictly obeying the constraint that you should use the affected Java version.
Assuming that you can identify an appropriate version in the OpenJDK source repos, it would be possible to build your own flavor of the Java libraries with a bug patched. However, that won't be real Java. Certainly, it won't qualify as "the affected Java version" that you are constrained to use. (And besides, you are committing yourself to an endless cycle of reapplying your patch to each new patch release of the current version of Java ...)
It is also possible in theory to put a modified version of some Java standard library class into a JAR and prepend it to the JVM's bootstrap classpath using the -Xbootclasspath command line option. But that is tantamount to changing "the affected Java version" too.
Doing it by using a Java agent to use a patched version of the class is breaking the rules too. And it is more complicated. (If you are going to break your rules, do it the easy way ...)
If you and your customers do decide that tweaking the JVM is an acceptable solution, then doing it via the bootstrap classpath is probably the simplest and cleanest approach. And it is DEFINITELY legal1.
However, I'd recommend that you find a workaround for the bug until a version of Java 9 with your fix is released.
1 - Actually, even the build-from-modified-source approach is legal, because the Oracle Binary license does not apply to that. The Binary license is about distributing a modified version of an Oracle binary. The other possible issue is that you may be violating the terms for using the Java trademark(s) if you distribute a version that is incompatible with "true" Java, and call your distro "Java". The solution to that is ... don't call it "Java"!
However, don't just follow my advice. Ask a lawyer. Better yet, don't do it at all. It is unnecessarily complicated.

Guava in Eclipse - Range "cannot be resolved to a type"

I'm trying to implement Google Guava in Eclipse for the Range class. As far as I can tell I've imported the Guava library successfully, but when I try to instantiate a new range, as below, I receive the error "Range cannot be resolved to a type."
import com.google.*;
public class RangeTest {
Range<Integer> testRange = Range.closed(1, 5);
}
I believe I'm missing either some sort of static import, or something in the method syntax.
I'm currently working through Standford's CS106a curriculum (though Guava is for an unrelated project), so I'm using JRE 1.6 and the "Standford Eclipse" SDK. I've tried using Dollar instead, and have been able to get it working with a static import. New to Java and programming in general.

The Javadocs contain a complete list of packages provided by Guava, and com.google isn't a package. As August notes the * isn't recursive - it means "import all classes in this package. Since there are no classes in com.google this statement does nothing.
This is one of many reasons why wildcard imports are problematic, and often discouraged (e.g. in Google's style guide). If you'd written import com.google.common.collect.Range; you'd be off to the races.