ajalt
Warning "A restricted method in java.lang.System has been called" is printed with Java24
Tnx for providing clikt. Clikt is used in ktlint. During some tests I noticed that the "--help" command on Java 24 results in printing the warning below:
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by com.sun.jna.Native in an unnamed module (file:/Users/xxx/clikt/samples/repo/build/install/repo/lib/jna-5.14.0.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
The problem can be reproduced with the sample repo of clikt. With Java 21 the output of ./runsample repo is:
Usage: repo [<options>] <command> [<args>]...
Repo is a command line tool that showcases how to build complex command line interfaces with Clikt.
This tool is supposed to look like a distributed version control system to show how something like this can be structured.
Options:
--version Show the version and exit
--repo-home=<text> Changes the repository folder location.
--config=<text>... Overrides a config key/value pair.
-v, --verbose Enables verbose mode.
-h, --help Show this message and exit
Commands:
clone Clones a repository.
delete Deletes a repository.
setuser Sets the user credentials.
commit Commits outstanding changes.
With Java 24 the output of ./runsample repo is:
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by net.rubygrapefruit.platform.internal.NativeLibraryLoader in an unnamed module (file:/Users/pdingemans/.gradle/wrapper/dists/gradle-8.10-bin/deqhafrv1ntovfmgh0nh3npr9/gradle-8.10/lib/native-platform-0.22-milestone-26.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
WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by com.sun.jna.Native in an unnamed module (file:/xxx/clikt/samples/repo/build/install/repo/lib/jna-5.14.0.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
Usage: repo [<options>] <command> [<args>]...
The first block of warning is produced while building. The second block while executing --help.
This is https://openjdk.org/jeps/472. The first one is from Gradle, they'll probably suppress at some point, likely in version 9. The second one is from Clikt and will occur whether you're using JNA or FFM. You will have to add the suppression from the message to your start script to suppress.
This is mentioned in the mordant docs, but it's hard to find, and with Java 24 becoming more widespread, it's worth making that info more prominent.
