System properties provided with `scala -Dname=prop` option passed to `main` as part of `args` / ignored

[ahrenberg]

Compiler version

3.2.1

Minimized code

object SyspropTest {

  def main(args: Array[String]) : Unit = {
    val n = "a.b"
    val v = System.getProperty(n)
    println(s"${n}=${v}")
    val argStr = args.mkString(", ")
    println(s"Command-line arguments: ${argStr}")
  }

}

Output

If first compiled with scalac, then executed as scala -Da.b=c SyspropTest 1 2 3:

a.b=null
Command-line arguments: -Da.b=c, 1, 2, 3

Expectation

a.b=c
Command-line arguments: 1, 2, 3

Notes

1. The output above is the result of first calling scalac followed by scala. However if the source file is sent directly to scala (instead of being compiled first) result differs in that the -Dname=prop option is silently dropped, while still not setting the property. That is, scala -Da.b=c sysprop.scala 1 2 3 (assuming that the example code above resides in file sysprop.scala) yields:

a.b=null
Command-line arguments: 1, 2, 3

Note that while the option is not part of args in this case, the property remains null.

2. It is possible to work around the issue by employing the -J command line option. scala -J-Da.b=c SyspropTest 1 2 3 gives the expected result (as -J is stripped and -Da.b=c passed to java)

a.b=c
Command-line arguments: 1, 2, 3

If needed - java -version:

openjdk version "11.0.17" 2022-10-18
OpenJDK Runtime Environment (build 11.0.17+8-post-Ubuntu-1ubuntu220.04)
OpenJDK 64-Bit Server VM (build 11.0.17+8-post-Ubuntu-1ubuntu220.04, mixed mode, sharing)