fix buggy Java version check in Scaladoc tool

[SethTisue]

this is a post-2.13.1 regression, due to #8663

the bug was that the Java version might be e.g. "14", with
no . character at all, causing StringIndexOutOfBoundsException

this was caught by the Scala community build

[som-snytt]

We have the hardened ScalaVersion which is also used for Java versions.

[SethTisue]

We have the hardened ScalaVersion which is also used for Java versions

Interesting, thank you, I was not aware.

It chokes on the underscores in some java.version strings, but (come to think of it) it's actually more appropriate to use java.specification.version, and ScalaVersion indeed handled the ones I tested it on.

The reuse is tempting, but in this context I think I'm a bit more comfortable going with the following (IMO) maximally robust code:

  lazy val javaVersion: Int =
    System.getProperty("java.specification.version").split('.').take(2).map(_.toIntOption) match {
      case Array(Some(1), Some(n)) => n   // example: 1.8.0_242
      case Array(Some(n))          => n   // example: 14
      case Array(Some(n), _)       => n   // example: 11.0.7
      case _                       => 8   // shrug!
    }

I want to get this merged so I can re-run the CB and get 2.13.2 out, but I'd be fine with further revisions.

[som-snytt]

Jason said somewhere once he reused it for Java versions. I guess I can grep for it. I had touched ScalaVersion, and I also remember a laborious thing about soc wanting version checking to have no dependencies (in particular, no regex).

[som-snytt]

Oh, it was "just a test":

./src/partest/scala/tools/partest/DirectTest.scala:  // the "ScalaVersion" class parses Java specification versions just fine
./src/partest/scala/tools/partest/DirectTest.scala:  val requiredJavaVersion = ScalaVersion(version)
./src/partest/scala/tools/partest/DirectTest.scala:  val executingJavaVersion = ScalaVersion(javaVersion)

[SethTisue]

god forbid that System.getProperty("java.specification.version") returns null when running in some weird JVM embedded in your Dustbuster or something like that

[som-snytt]

case Array(Some(v), _*) => v for both cases.

[SethTisue]

+1 cleverness, -1 readability

[som-snytt]

*_*)

[som-snytt]

.split('.') is augmentString, split("\\.") is java which notices it's a split on literal char, not a pattern. Just to footnote, as I always have to look it up.

[som-snytt]

TIL 8 is the new shrug emoji.

[som-snytt]

Oh, soc was about util.Properties. You could count from 8 [shrug] until isJavaAtLeast(version: Int) is falsified! That tests javaSpecVersion.

[SethTisue]

de-duplicating this with isJavaAtLeast would be a great cleanup for..... somebody

[som-snytt]

The big S on my chest stands for ... Somebody.

[SethTisue]

somebody sombody <-- geez, how'd I miss this pun opportunity. I must be slipping

[som-snytt]

I was literally in the middle of editing my strike-thru.

[SethTisue]

we're here all night or until CI is green, whichever comes first

[som-snytt]

re-run the CB

Ten-four, looks like we got us a convoy.