Add +1 to zinc positions in the compiler bridge

Author: tgodzik

sbt-bridge/src/xsbt/DelegatingReporter.java

@@ -88,7 +88,7 @@ public Optional<String> sourcePath() {
           else return Optional.ofNullable(src.file().path());
         }
         public Optional<Integer> line() {
-          int line = pos.line();
+          int line = pos.line() + 1;
           if (line == -1) return Optional.empty();
           else return Optional.of(line);
         }

sbt-dotty/sbt-test/compilerReporter/simple/project/Reporter.scala

@@ -29,6 +29,12 @@ object Reporter {
       println(problems.toList)
       assert(problems.size == 1)
 
+      // make sure position reported by zinc are proper
+      val mainProblem = problems.head
+      val line = mainProblem.position().line() 
+      assert(line.isPresent() == true)
+      assert(line.get() == 9)
+      
       // Assert disabled because we don't currently pass positions to sbt
       // See https://github.com/lampepfl/dotty/pull/2107
       // assert(problems.forall(_.position.offset.isDefined))