ManPageGenerator as subcommand with native-image throws exception

[sebhoss]

Heyho,

using ManPageGenerator as a subcommand fails when I compile the application as a native image with the following stack trace. Running it as a Java app works fine though.

Exception in thread "main" picocli.CommandLine$InitializationException: picocli.codegen.docgen.manpage.ManPageGenerator$Config@6408c574 is not a command: it has no @Command, @Option, @Parameters or @Unmatched annotations
        at picocli.CommandLine$Model$CommandReflection.validateCommandSpec(CommandLine.java:10905)
        at picocli.CommandLine$Model$CommandReflection.extractCommandSpec(CommandLine.java:10741)
        at picocli.CommandLine$Model$CommandSpec.forAnnotatedObject(CommandLine.java:5863)
        at picocli.CommandLine$Model$CommandReflection.buildMixinForMember(CommandLine.java:10936)
        at picocli.CommandLine$Model$CommandReflection.initFromAnnotatedTypedMembers(CommandLine.java:10821)
        at picocli.CommandLine$Model$CommandReflection.initFromAnnotatedFields(CommandLine.java:10800)
        at picocli.CommandLine$Model$CommandReflection.extractCommandSpec(CommandLine.java:10731)
        at picocli.CommandLine$Model$CommandSpec.forAnnotatedObject(CommandLine.java:5863)
        at picocli.CommandLine.<init>(CommandLine.java:223)
        at picocli.CommandLine.toCommandLine(CommandLine.java:3496)
        at picocli.CommandLine.access$14300(CommandLine.java:145)
        at picocli.CommandLine$Model$CommandReflection.initSubcommands(CommandLine.java:10765)
        at picocli.CommandLine$Model$CommandReflection.extractCommandSpec(CommandLine.java:10727)
        at picocli.CommandLine$Model$CommandSpec.forAnnotatedObject(CommandLine.java:5863)
        at picocli.CommandLine.<init>(CommandLine.java:223)
        at picocli.CommandLine.<init>(CommandLine.java:196)

This is using the latest Graal 20.2 with pico 4.5.0 on Java 11.

[remkop]

Ouch! Thanks for letting me know. Investigating...

[remkop]

@sebhoss Update: I was able to reproduce the issue and create a failing test for it.

The problem (based on my analysis so far) is that the reflect-config.json file generated by the picocli-codegen annotation processor is incomplete and does not contain the names of the @Option-annotated fields of the ManPageGenerator$Config class. This results in the native image failing when the ManPageGenerator subcommand is invoked, with the exception you reported.

In my test, I found that the picocli-codegen annotation processor only receives the class of the parent command, and not the ManPageGenerator subcommand. I guess this is since the ManPageGenerator subcommand has already been compiled to a .class file. The annotation processor is not ready for this scenario.

I have a few ideas about how to solve this, but this will take me some time.
I will let you know when I make more progress on this.

[sebhoss]

That's a very cool test!

I could actually live without the command, so take all the time you need. If there is anything I can do to help/investigate/test, let me know - happy to help.

[remkop]

I pushed a fix for this to master.
I will do a 4.5.1 bugfix release soon (in the next day or so).

[remkop]

@sebhoss Picocli 4.5.1 has been released, with a fix for this issue.

Don't forget to star ⭐ picocli on GitHub if you like the project! 😉

[sebhoss]

Nice, thanks a lot!