allow reflection metadata for classes that reference undefined classes

[kkriske]

This is a fix for #2207

Native-image does not allow reflection registration of classes referencing undefined classes, for example in the case of optional dependencies in 3rd party libraries.

A simple example of this goes as follows: (copied from what I wrote here #2207 (comment))

file: UndefinedReferencePoc.java

class UndefinedReferencePoc {
    public static void main(String[] args) throws Exception {
		Library lib = (Library)Class.forName(args[0]).getDeclaredConstructor().newInstance();
		lib.doStuff();
    }
}

interface Library {
	public void doStuff();
	public DeleteMe unused();
	public void unused2(DeleteMe d);
}

class LibraryImpl implements Library {
	public void doStuff() {
		System.out.println("Hello from LibraryImpl");
	}
	
	public DeleteMe unused() { return null; }
	public void unused2(DeleteMe d) {}
}

class DeleteMe {
}

file: reflect-config.json

[
  {
    "name" : "LibraryImpl",
    "methods" : [
      {"name":"<init>","parameterTypes":[] }
    ]
  }
]

Steps to reproduce:

1. javac UndefinedReferencePoc.java
2. delete the DeleteMe.class file
3. run native-image: native-image -H:Name=UndefinedReferencePoc -H:Class=UndefinedReferencePoc --verbose --no-fallback --allow-incomplete-classpath -H:ReflectionConfigurationResources=reflect-config.json
4. Build contains a single warning:

[UndefinedReferencePoc:37576]    classlist:   1,082.90 ms,  0.96 GB
[UndefinedReferencePoc:37576]        (cap):   1,901.77 ms,  0.96 GB
[UndefinedReferencePoc:37576]        setup:   3,716.32 ms,  0.96 GB
WARNING: Could not register reflection metadata for LibraryImpl. Reason: java.lang.NoClassDefFoundError: DeleteMe.
[UndefinedReferencePoc:37576]     (clinit):     184.87 ms,  1.20 GB
[UndefinedReferencePoc:37576]   (typeflow):   3,905.18 ms,  1.20 GB
[UndefinedReferencePoc:37576]    (objects):   3,465.75 ms,  1.20 GB
[UndefinedReferencePoc:37576]   (features):     229.58 ms,  1.20 GB
[UndefinedReferencePoc:37576]     analysis:   7,952.53 ms,  1.20 GB
[UndefinedReferencePoc:37576]     universe:     378.90 ms,  1.22 GB
[UndefinedReferencePoc:37576]      (parse):     745.56 ms,  1.22 GB
[UndefinedReferencePoc:37576]     (inline):     977.44 ms,  1.67 GB
[UndefinedReferencePoc:37576]    (compile):   4,777.54 ms,  2.25 GB
[UndefinedReferencePoc:37576]      compile:   6,914.18 ms,  2.25 GB
[UndefinedReferencePoc:37576]        image:     929.00 ms,  2.25 GB
[UndefinedReferencePoc:37576]        write:     323.54 ms,  2.25 GB
[UndefinedReferencePoc:37576]      [total]:  21,482.00 ms,  2.25 GB

• running from java:

 > java UndefinedReferencePoc LibraryImpl
Hello from LibraryImpl

• running the native image:

 > UndefinedReferencePoc.exe LibraryImpl
Exception in thread "main" java.lang.NoSuchMethodException: LibraryImpl.<init>()
        at java.lang.Class.getConstructor0(DynamicHub.java:3349)
        at java.lang.Class.getDeclaredConstructor(DynamicHub.java:2553)
        at UndefinedReferencePoc.main(UndefinedReferencePoc.java:3)

This PR fixes this by splitting up the verification to only check fields/methods/constructors/classes if there is reflection config present for them.

[kkriske]

This case no longer has any of the verification calls, I am not sure if this is ok.

[graalvmbot]

Hello Kristof Dhondt, thanks for contributing a PR to our project!

We use the Oracle Contributor Agreement to make the copyright of contributions clear. We don't have a record of you having signed this yet, based on your email address kristofdho -(at)- gmail -(dot)- com. You can sign it at that link.

If you think you've already signed it, please comment below and we'll check.

[kkriske]

OCA has been submitted and accepted.

[graalvmbot]

Kristof Dhondt has signed the Oracle Contributor Agreement (based on email address kristofdho -(at)- gmail -(dot)- com) so can contribute to this repository.