Generated GraalVM reflection configuration can exclude Jansi Console

[shanetreacy]

When generating the reflection configuration by running the generateGraalReflectionConfig gradle task, the AnsiConsole class is picked up and included in the output.

  {
    "name" : "org.fusesource.jansi.AnsiConsole",
    "allDeclaredConstructors" : true,
    "allPublicConstructors" : true,
    "allDeclaredMethods" : true,
    "allPublicMethods" : true,
    "fields" : [
      { "name" : "out" }
    ]
  }

Giving this error when attempting to generate a nativeImage

error: Error parsing reflection configuration in blah/build/cli-reflect.json:
Class org.fusesource.jansi.AnsiConsole not found
Verify that the configuration matches the schema described in the -H:PrintFlags=+ output for option ReflectionConfigurationFiles.
Error: Image building with exit status 1

Manually removing the AnsiConsole block from the reflection configuration allows native image to build successfully.

Similar to issue #630

[remkop]

The error occurs because the jansi jar is missing from the classpath. Adding it to the classpath when generating the GraalVM native image is another way to resolve this error.

I understand that this is not strictly necessary because GraalVM does not yet support native images for Windows, so it is probably okay to exclude the org.fusesource.jansi.AnsiConsole class from the generated reflect.json file. (It'll be interesting to see what happens when running the resulting native image when system property "os.name" is set to "Windows", and GraalVM does reflection on an unknown class.)

Do you think you will be able to provide a pull request for this?

[remkop]

Pushed to master.
This will be included in 4.0.0-alpha-3 and later.

[remkop]

Reopening since Graal GA was released in the last few days with native-image capabilities for Windows.
This means that it makes sense to include Jansi again in some cases.

I will add a command line flag for the gen-reflect-config tool to optionally include configuration for the org.fusesource.jansi.AnsiConsole class. This flag will be false by default, so users need to explicitly request it to be included. I will update the documentation accordingly.

[remkop]

Actually, I found a better way to do this.

picocli can now detect whether Jansi was installed without reflecting on any Jansi classes.
This has two advantages:

• avoids loading the Jansi classes, so no native libraries are loaded (avoiding issues like JVM crash on RedHat Linux when loading jansi.AnsiConsole #630)
• no need to include configuration for org.fusesource.jansi.AnsiConsole in the reflect-config.json file