Parse JVM 9 version correctly

modules/bloop-rifle/src/main/scala/scala/build/blooprifle/VersionUtil.scala

@@ -1,10 +1,27 @@
 package scala.build.blooprifle
 
+
 object VersionUtil {
-  def jvmRelease(jvmVersion: String): Option[Int] = {
-    val jvmReleaseRegex = "(1[.])?(\\d+)".r
-    jvmReleaseRegex.findFirstMatchIn(jvmVersion).map(_.group(2)).map(_.toInt)
-  }
+
+  /** @param jvmVersion,
+    *   for example '1.8.0.22' or '11.0.2'
+    * @return
+    *   jvm release version (8, 11)
+    */
+  val jvmReleaseRegex = "(1[.])?(\\d+)"
+  def jvmRelease(jvmVersion: String): Option[Int] =
+    jvmReleaseRegex.r.findFirstMatchIn(jvmVersion).map(_.group(2)).map(_.toInt)
+
+  /** @param input
+    *   `java -version` output`
+    * @return
+    *   jvm release version (8, 11)
+    */
+  def parseJavaVersion(input: String): Option[Int] = for {
+    firstMatch         <- s""".*version .($jvmReleaseRegex).*""".r.findFirstMatchIn(input)
+    versionNumberGroup <- Option(firstMatch.group(1))
+    versionInt         <- jvmRelease(versionNumberGroup)
+  } yield versionInt
 
   def parseBloopAbout(stdoutFromBloopAbout: String): Option[BloopServerRuntimeInfo] = {
 

modules/bloop-rifle/src/test/scala/scala/build/blooprifle/ParsingTests.scala

@@ -2,14 +2,15 @@ package scala.build.blooprifle
 
 import com.eed3si9n.expecty.Expecty.expect
 
-import scala.build.blooprifle.VersionUtil.{jvmRelease, parseBloopAbout}
+import scala.build.blooprifle.VersionUtil.{jvmRelease, parseBloopAbout, parseJavaVersion}
 
 class ParsingTests extends munit.FunSuite {
 
   implicit class BV(s: String) {
-    implicit def v = BloopVersion(s)
-    implicit def p = parseBloopAbout(s)
-    implicit def j = jvmRelease(s)
+    implicit def v  = BloopVersion(s)
+    implicit def p  = parseBloopAbout(s)
+    implicit def j  = jvmRelease(s)
+    implicit def jv = parseJavaVersion(s)
   }
 
   test("bloop version comparisons test") {
@@ -31,6 +32,13 @@ class ParsingTests extends munit.FunSuite {
     expect("17".j == Some(17))
   }
 
+  test("parse jvm version") {
+    expect("""openjdk version "1.8.0_292" """.jv == Some(8))
+    expect("""openjdk version "9" """.jv == Some(9))
+    expect("""openjdk version "11.0.11" 2021-04-20 """.jv == Some(11))
+    expect("""openjdk version "16" 2021-03-16 """.jv == Some(16))
+  }
+
   val jreBloopOutput =
     """|bloop v1.4.11
        |

modules/build/src/main/scala/scala/build/options/BuildOptions.scala

@@ -10,6 +10,7 @@ import java.nio.file.Path
 import java.security.MessageDigest
 
 import scala.build.EitherCps.{either, value}
+import scala.build.blooprifle.VersionUtil.parseJavaVersion
 import scala.build.errors.{BuildException, Diagnostic, InvalidBinaryScalaVersionError}
 import scala.build.internal.Constants._
 import scala.build.internal.{Constants, OsLibc, Util}
@@ -127,22 +128,16 @@ final case class BuildOptions(
     val ext      = if (Properties.isWin) ".exe" else ""
     val javaCmd  = (javaHome / "bin" / s"java$ext").toString
 
-    val javaV0 = os.proc(javaCmd, "-version").call(
+    val javaVersionOutput = os.proc(javaCmd, "-version").call(
       cwd = os.pwd,
       stdout = os.Pipe,
       stderr = os.Pipe,
       mergeErrIntoOut = true
     ).out.text().trim()
-    val javaFullVersion = javaV0.split(" ").lift(2).map(_.replace("\"", ""))
-    val javaReleaseVersion =
-      javaFullVersion.flatMap(_.trim.stripPrefix("1.").split("[.]").headOption)
-
-    val javaVersion =
-      try javaReleaseVersion.get.toInt
-      catch {
-        case e: Throwable =>
-          throw new Exception(s"Could not parse java version from output: $javaV0", e)
-      }
+    val javaVersion = parseJavaVersion(javaVersionOutput).getOrElse {
+      throw new Exception(s"Could not parse java version from output: $javaVersionOutput")
+    }
+
     JavaHomeInfo(javaCmd, javaVersion)
   }