redo how crossScalaVersions works

the old scheme was: run tests on openjdk7 too, but only publish (for
all Scala versions) from openjdk6

this is no longer appropriate now that Scala 2.12.0-M2 requires Java 8.
now we want to publish for older Scala versions using JDK 6, but
newer versions (M2 and above) using JDK 8. this commit does that.

currently Travis doesn't offer OpenJDK 8, so we use Oracle.  leaving
our JDK 6 setting as "openjdk6" since that's what it's historically
been so why rock the boat.

what happened to running tests on JDK 7?  well, neither Lukas nor I
knows why it was even doing that.

.travis.yml

@@ -2,7 +2,6 @@ language: scala
 
 env:
   global:
-    - PUBLISH_JDK=openjdk6
     # PGP_PASSPHRASE
     - secure: "BYC1kEnHjNrINrHYWPGEuTTJ2V340/0ByzqeihLecjoZ75yrjWdsh6MI1JEUWgv5kb+58vLzib21JfnjsPK6Yb2bSXuCFCsEtJNh6RJKgxkWlCOzfTSh5I2wl7PCjRClRL6gseX2uTSvFjL4Z//pmxwxeXlLp7voQe4QAUq1+sE="
     # SONA_USER
@@ -14,7 +13,7 @@ script: admin/build.sh
 
 jdk:
   - openjdk6
-  - openjdk7
+  - oraclejdk8
 
 notifications:
   email: adriaan.moors@typesafe.com

admin/README.md

@@ -19,7 +19,8 @@ To configure tag driven releases from Travis CI.
      Edit `.travis.yml` as prompted.
   4. Edit `.travis.yml` to use `./admin/build.sh` as the build script,
      and edit that script to use the tasks required for this project.
-  5. Edit `.travis.yml` to select which JDK will be used for publishing.
+  5. Edit `build.sbt` to select which JDK will be used for publishing
+     for which Scala versions.
 
 It is important to add comments in .travis.yml to identify the name
 of each environment variable encoded in a `:secure` section.
@@ -30,7 +31,6 @@ form:
 	language: scala
 	env:
 	  global:
-	    - PUBLISH_JDK=openjdk6
 	    # PGP_PASSPHRASE
 	    - secure: "XXXXXX"
 	    # SONA_USER
@@ -58,4 +58,3 @@ Be sure to use SBT 0.13.7 or higher to avoid [#1430](https://github.com/sbt/sbt/
   3. Log into https://oss.sonatype.org/ and identify the staging repository.
   4. Sanity check its contents
   5. Release staging repository to Maven and send out release announcement.
-

admin/build.sh

@@ -7,7 +7,7 @@ set -e
 # git on travis does not fetch tags, but we have TRAVIS_TAG
 # headTag=$(git describe --exact-match ||:)
 
-if [ "$TRAVIS_JDK_VERSION" == "$PUBLISH_JDK" ] && [[ "$TRAVIS_TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[A-Za-z0-9-]+)? ]]; then
+if [[ "$TRAVIS_TAG" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[A-Za-z0-9-]+)? ]]; then
   echo "Going to release from tag $TRAVIS_TAG!"
   myVer=$(echo $TRAVIS_TAG | sed -e s/^v//)
   publishVersion='set every version := "'$myVer'"'

build.sbt

@@ -8,9 +8,17 @@ version                    := "1.0.5-SNAPSHOT"
 
 scalaVersion               := crossScalaVersions.value.head
 
-crossScalaVersions         := Seq("2.11.7", "2.12.0-M2")
-
-//scalacOptions             ++= "-deprecation:false -feature -Xlint:-stars-align,-nullary-unit,_ -Xfatal-warnings -Xxml:coalescing".split("\\s+").to[Seq]
+crossScalaVersions         := {
+  val java = System.getProperty("java.version")
+  if (java.startsWith("1.6."))
+    Seq("2.11.7", "2.12.0-M1")
+  else if (java.startsWith("1.8."))
+    Seq("2.12.0-M2")
+  else
+    sys.error(s"don't know what Scala versions to build on $java")
+}
+
+//reenable -Xfatal-warnings?
 scalacOptions             ++= "-deprecation:false -feature -Xlint:-stars-align,-nullary-unit,_".split("\\s+").to[Seq]
 
 scalacOptions in Test      += "-Xxml:coalescing"