Java 9+: WARNING: Illegal reflective access by sbt.internal.inc.javac.DiagnosticsReporter$PositionImpl$

[mkurz]

Environment:

$ java -version
openjdk version "11.0.2" 2019-01-15
OpenJDK Runtime Environment 18.9 (build 11.0.2+9)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.2+9, mixed mode)

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.2 LTS
Release:	18.04
Codename:	bionic

$ uname -a
Linux 4.15.0-48-generic #51-Ubuntu SMP Wed Apr 3 08:28:49 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

How to reproduce:

$ sbt new playframework/play-java-seed.g8
...
name [play-java-seed]: <enter>
organization [com.example]: <enter>
...
$ cd play-java-seed/
play-java-seed$ echo "sbt.version=1.3.0-M3" > project/build.properties
play-java-seed$ sbt
[play-java-seed] $ compile

You should see following warning:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by sbt.internal.inc.javac.DiagnosticsReporter$PositionImpl$ (file:/home/mkurz/.sbt/boot/scala-2.12.8/org.scala-sbt/sbt/1.3.0-M3/zinc-compile-core_2.12-1.3.0-M4.jar) to field com.sun.tools.javac.api.ClientCodeWrapper$DiagnosticSourceUnwrapper.d
WARNING: Please consider reporting this to the maintainers of sbt.internal.inc.javac.DiagnosticsReporter$PositionImpl$
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

[eed3si9n]

Looks like reflection was introduced in sbt/sbt#2108 to get a better line content in the compiler error messages.

Ref #465
https://docs.oracle.com/javase/8/docs/api/javax/tools/Diagnostic.html
https://docs.oracle.com/javase/8/docs/api/javax/tools/JavaFileObject.html
https://docs.oracle.com/en/java/javase/11/docs/api/java.compiler/javax/tools/Diagnostic.html