Incorrect JAVA_HOME setting

[schiele]

I believe the JAVA_HOME setting introduced in

commit b38fb071d8c77ef82d57c7f0c97d42b309ce7310 (HEAD -> main, tag: 3.0.14-248, origin/main, origin/HEAD)
Author: William Douglas <[email protected]>
Date:   Mon Dec 9 15:22:45 2024 -0800

    Update for new java version.
    
    Signed-off-by: William Douglas <[email protected]>

is incorrect.
The symptom I observed first after introducing this was that Bazel can no longer build itself, breaking in the process by not finding jrt-fs.jar.
Analysing the problem revealed that this file indeed does not exist in /usr/lib/jvm/java-1.21.0 but instead can be found in /usr/lib/jvm/openjdk-21.0.5-internal and indeed this is apparently how the Java package seems to be built:

$ java -XshowSettings 2>&1 | grep java.home
    java.home = /usr/lib/jvm/openjdk-21.0.5-internal

Further inspecting those directories it seems that /usr/lib/jvm/java-1.21.0 is a weird incomplete subset of /usr/lib/jvm/openjdk-21.0.5-internal. Me not being a real OpenJDK expert I am not sure what the purpose of this duplicate structure is but after my investigation I am convinced that JAVA_HOME, if we feel that we need to set this to an explicit location for applications that are not capable of extracting the information from Java itself, it should point to /usr/lib/jvm/openjdk-21.0.5-internal.

Along this reasoning we probably should also set JAVA_INCLUDE_PATH to /usr/lib/jvm/openjdk-21.0.5-internal/include.

[Aqua1ung]

As far as I can tell, this seems to have been fixed in #43000. Is that so?

[bryteise]

I attempted at least.