Fix scala#5055: Run tests with Java 11

.drone.yml

@@ -42,6 +42,16 @@ pipeline:
       - git submodule update --init --recursive --jobs 7
       - ./project/scripts/sbt community-build/test
 
+  test_bootstrapped_java11:
+    group: test
+    image: lampepfl/dotty:2019-04-22
+    commands:
+      - export JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64/"
+      - cp -R . /tmp/6/ && cd /tmp/6/
+      - ./project/scripts/sbt ";compile ;test"
+    # when:
+    #   event: [ push, tag, deployment ]
+
   test_sbt:
     group: test
     image: lampepfl/dotty:2019-04-22

project/scripts/sbt

@@ -6,11 +6,18 @@ set -e
 
 CMD="${1:?Missing sbt command}"
 
+if [ -z "$JAVA_HOME" ]; then
+  SET_JAVA_VERSION=""
+else
+  SET_JAVA_VERSION="-java-home"
+fi
+
 # run sbt with the supplied arg
 sbt -J-Xmx4096m \
     -J-XX:ReservedCodeCacheSize=512m \
     -J-XX:MaxMetaspaceSize=1024m \
     -Ddotty.drone.mem=4096m \
     -Dsbt.ivy.home=/var/cache/drone/ivy2 \
     -no-colors \
+    "$SET_JAVA_VERSION" "$JAVA_HOME" \
     "$CMD"