Java 17 compatibility

[iemejia]

It seems that Java 17 (next LTS) will have stricter access requirements
https://openjdk.java.net/jeps/403

I tried to run this tool and noticed this error:

Caused by: java.lang.IllegalAccessError: class com.google.googlejavaformat.java.RemoveUnusedImports (in unnamed module @0x5c25324c) cannot access class com.sun.tools.javac.util.Context (in module jdk.compiler) because module jdk.compiler does not export com.sun.tools.javac.util to unnamed module @0x5c25324c
        at com.google.googlejavaformat.java.RemoveUnusedImports.removeUnusedImports(RemoveUnusedImports.java:188)

[cushon]

(in unnamed module @0x5c25324c) cannot access class com.sun.tools.javac.util.Context (in module jdk.compiler)

You'll need to add the --add-exports= flags documented here to run the formatter on JDK 16 and newer: https://github.com/google/google-java-format#jdk-16

[iemejia]

I am using google-java-format via spotless so I can workaround this with --add-exports on MAVEN_OPTS as suggested also here diffplug/spotless#834

Is there a way this can be fixed out of the box for users of the library or would it require the full Java module stuff?

[cushon]

Is there a way this can be fixed out of the box for users of the library or would it require the full Java module stuff?

I don't know any good alternatives: --add-exports= has to be passed at the top level, there isn't a supported way for a library like google-java-format to disable those access checks for all uses of the library.

[iemejia]

Thanks @cushon !

[fcurts]

What's the long-term solution?

• --add-exports is meant to be used as a temporary workaround. It can break in any new Java version, at which point users of google-java-format won't be able to upgrade.
• Depending on the build tool and environment, --add-exports can be difficult to set (it took me half a day).

[cushon]

• --add-exports is meant to be used as a temporary workaround. It can break in any new Java version, at which point users of google-java-format won't be able to upgrade.

--illegal-access was removed in JEP 369, but I'm not aware of any long-term plans to remove --add-exports or --add-opens

[fcurts]

I'm not aware of any long-term plans to remove --add-exports or --add-opens

Are you effectively saying that google-java-format intentionally depends on JDK internals, accepting the risk that it can break any time a new JDK version comes out?

[davidyscott]

With Java 17 GA only 6 days away, some further insight on your plans to address this issue would be greatly appreciated.

[cushon]

The plan is to continue using --add-exports=, and to support JDK 17 and future Java versions.

JDK 17 should already work and is being tested on CI, if you see issues with it or other upcoming versions please report them.

[davidyscott]

It seems pretty unreasonable to require all users to jump through that sort of hoop.