Custom IParameterConsumer causes native-image to fail

[byteit101]

Using a file with a custom parameter consumer:

import picocli.CommandLine.*;
import picocli.CommandLine.Model.*;
import java.util.Stack;
import java.util.concurrent.Callable;
import picocli.CommandLine;

@Command(name = "checksum", mixinStandardHelpOptions = true, version = "checksum 4.0", description = "Prints the checksum (MD5 by default) of a file to STDOUT.")
public class Boom implements Callable<Integer> {
	@Parameters(index = "0", description = "Ignored", parameterConsumer = LocalPC.class)
	private String file;
	public static void main(String... args) {
		System.exit(new CommandLine(new Boom()).execute(args));
	}
	@Override public Integer call() throws Exception {return 0;}
}
class LocalPC implements IParameterConsumer {
	@Override public void consumeParameters(Stack<String> args, ArgSpec argSpec, CommandSpec commandSpec) {return;}
}

$ java -cp boom.jar:picocli-codegen-4.0.3.jar picocli.codegen.aot.graalvm.ReflectionConfigGenerator Boom  > test.json
$ native-image -jar boom.jar -H:ReflectionConfigurationFiles=test.json -H:+ReportUnsupportedElementsAtRuntime --no-server
$ ./boom --help                                                                                                                                          ] EP_BAD 4:54 PM
Exception in thread "main" picocli.CommandLine$InitializationException: Could not instantiate class LocalPC: java.lang.NoSuchMethodException: LocalPC.<init>
	at picocli.CommandLine$DefaultFactory.create(CommandLine.java:4749)
	at picocli.CommandLine$DefaultFactory.createParameterConsumer(CommandLine.java:4745)
	at picocli.CommandLine$Model$ArgSpec$Builder.<init>(CommandLine.java:7662)
	at picocli.CommandLine$Model$PositionalParamSpec$Builder.<init>(CommandLine.java:8271)
	at picocli.CommandLine$Model$PositionalParamSpec$Builder.<init>(CommandLine.java:8261)
	at picocli.CommandLine$Model$PositionalParamSpec.builder(CommandLine.java:8220)
	at picocli.CommandLine$Model$CommandReflection.buildArgForMember(CommandLine.java:9773)
	at picocli.CommandLine$Model$CommandReflection.initFromAnnotatedTypedMembers(CommandLine.java:9688)
	at picocli.CommandLine$Model$CommandReflection.initFromAnnotatedFields(CommandLine.java:9641)
	at picocli.CommandLine$Model$CommandReflection.extractCommandSpec(CommandLine.java:9546)
	at picocli.CommandLine$Model$CommandSpec.forAnnotatedObject(CommandLine.java:5118)
	at picocli.CommandLine.<init>(CommandLine.java:223)
	at picocli.CommandLine.<init>(CommandLine.java:196)
	at Boom.main(Boom.java:14)
Caused by: java.lang.NoSuchMethodException: LocalPC.<init>
	at java.lang.Class.getConstructor0(DynamicHub.java:3082)
	at java.lang.Class.getDeclaredConstructor(DynamicHub.java:2178)
	at picocli.CommandLine$DefaultFactory.create(CommandLine.java:4725)
	at picocli.CommandLine$DefaultFactory.create(CommandLine.java:4748)
	... 13 more

The issue seems to be that the LocalPC class is not put into the reflection output by the ReflectionConfigGenerator, and manually putting it in I get it to build and show help successfully

[remkop]

Thank you for raising this issue and for the pull request!
I merged the PR but it would be good to add a test for this in picocli-annotation-processing-tests. Do you think you’ll be able to provide this?

[byteit101]

I added a commit to my branch that should, in theory, test for this fix, but I can't seem to get it to work, and I'm not sure if it's my weak gradle skills, or what.

[remkop]

@byteit101, it could be because I already merged that PR. Maybe create another branch?

[remkop]

I might have misread. Did you mean you have trouble getting the test to work? If you can share the code we can look at it together...

[byteit101]

Yes, the latter. I can't seem to get them to work. Works fine when I do a command line generation, but through gradle test it fails. Code is byteit101@1e7b2f5 and I'm kinda stuck. Looks to me like it should work, but I'm clearly missing something, either in gradle (gradle n00b here), or in your test framework, or something else.

[remkop]

Code looks fine to me too. Can you put it in a pull request?

[remkop]

I went ahead and released picocli 4.0.4 with your PR and the additional changes to the annotation processor to correctly handle parameterConsumer attribute in the @Option or @Parameters annotations.

Please verify that this solves the issue.
Thanks again for the contribution!

[pedrolamarao]

This happens to my code with picocli 4.6.1 running on OpenJDK 11.

[remkop]

Hi @pedrolamarao
Thanks for raising this.
Can you open a new ticket with some code to reproduce the issue? That would help me a lot!

[pedrolamarao]

I'll see to it next week. We discovered that this happens only if the parameter consumer is an inner non static class. An inner static class works. (If this is a known limitation, we totally missed it from the documentation.)

[remkop]

@pedrolamarao Thank you for the clarification.

Yes, that is a know limitation (for more details, see this ticket: #1297),
and perhaps this is an opportunity to improve the documentation! 😄
Any suggestions (or even better, PRs) would be much appreciated.

Thanks again for raising this!