Support JLine Jansi.

[garretwilson]

The picocli code currently has some code to see if Jansi is installed, e.g.

// loading this class will load the native library org.fusesource.jansi.internal.CLibrary
Class<?> ansiConsole = Class.forName("org.fusesource.jansi.AnsiConsole");
Field out = ansiConsole.getField("out");
return out.get(null) == System.out;

In the notes to the recent Jansi 2.4.2 release, I noticed they say:

⚠️ WARNING
This library is no longer maintained. It has been merged into org.jline:jansi.
Please update your dependencies to use org.jline:jansi instead.

There wasn't much other information, but I suppose they are referring to JLine. In its GitHub repository, I see that there are indeed similar classes, for example org.jline.jansi.AnsiConsole.

Admittedly there is little information about which we should be using, but it's not unreasonable to interpret this as saying we should switch to org.jline.jansi.AnsiConsole going forward. I haven't made that switch in my application yet, but it looks like when I do, it would only work if picocli adds support for it.

[loicgreffier]

After upgrading to Java 25, I’m seeing the following warnings:

WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by org.fusesource.jansi.internal.JansiLoader in an unnamed module (jar:nested:/C:/Users/LoicG/Downloads/docsource-jar/docsource-1.4.1-SNAPSHOT.jar/!BOOT-INF/lib/jansi-2.4.2.jar!/)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for callers in this module
WARNING: Restricted methods will be blocked in a future release unless native access is enabled

Switching to org.jline.jansi.AnsiConsole will be necessary to remove these warnings, since org.fusesource.jansi won't be updated?

[garretwilson]

Switching to org.jline.jansi.AnsiConsole will be necessary to remove these warnings, since org.fusesource.jansi won't be updated?

Neither version will address this warning, because the problem is that Jansi by nature is accessing some native code. You'll need to follow the directions in the warning. The issue is that Jansi needs to modularize so that you will be able to allow only certain modules to have native access, and not open up all modules for native access.

See:

• Restricted native access to java.lang.System fusesource/jansi#301
• WARNING: A restricted method in java.lang.System has been called (JDK24) jline/jline3#1067
• Build as Java 9 modules jline/jline3#70 (see especially my comment)

In any case, it looks like picocli needs to migrate to JLine Jansi (this ticket); the warning you're seeing is an orthogonal issue.