Explain message

modules/build/src/main/scala/scala/build/ConsoleBloopBuildClient.scala

@@ -174,7 +174,7 @@ object ConsoleBloopBuildClient {
       val prefix = diagnosticPrefix(diag.getSeverity)
 
       val line  = (diag.getRange.getStart.getLine + 1).toString + ":"
-      val col   = (diag.getRange.getStart.getCharacter + 1).toString + ":"
+      val col   = (diag.getRange.getStart.getCharacter + 1).toString
       val msgIt = diag.getMessage.linesIterator
 
       val path0 = path match {
@@ -183,9 +183,9 @@ object ConsoleBloopBuildClient {
           "." + File.separator + p.relativeTo(Os.pwd).toString
         case Right(p) => p.toString
       }
-      logger.error(s"$prefix$path0:$line$col" + (if (msgIt.hasNext) " " + msgIt.next() else ""))
+      logger.error(s"$prefix$path0:$line$col")
       for (line <- msgIt)
-        logger.message(prefix + line)
+        logger.error(prefix + line)
       val codeOpt = {
         val lineOpt =
           if (diag.getRange.getStart.getLine == diag.getRange.getEnd.getLine)

modules/integration/src/test/scala/scala/cli/integration/CompileTestDefinitions.scala

@@ -488,9 +488,8 @@ abstract class CompileTestDefinitions(val scalaVersionOpt: Option[String])
     test("generate scoverage.coverage file") {
       val fileName = "Hello.scala"
       val inputs = TestInputs(
-        os.rel / fileName -> // scala version should updated to 3.3 after release
-          s"""//> using scala "3.2.0-RC1-bin-20220604-13ce496-NIGHTLY"
-             |//> using options "-coverage-out:."
+        os.rel / fileName ->
+          s"""//> using options "-coverage-out:."
              |
              |@main def main = ()
              |""".stripMargin

modules/integration/src/test/scala/scala/cli/integration/CompileTestsDefault.scala

@@ -1,3 +1,23 @@
 package scala.cli.integration
 
-class CompileTestsDefault extends CompileTestDefinitions(scalaVersionOpt = None)
+import com.eed3si9n.expecty.Expecty.expect
+class CompileTestsDefault extends CompileTestDefinitions(scalaVersionOpt = None) {
+  test("render explain message") {
+    val fileName = "Hello.scala"
+    val inputs = TestInputs(
+      os.rel / fileName -> // should be dump to 3.3.1 after release
+        s"""//> using scala "3.3.1-RC1-bin-20230203-3ef1e73-NIGHTLY"
+           |//> using options "--explain"
+           |
+           |class A
+           |val i: Int = A()
+           |""".stripMargin
+    )
+    inputs.fromRoot { root =>
+      val out = os.proc(TestUtil.cli, "compile", extraOptions, fileName)
+        .call(cwd = root, check = false, mergeErrIntoOut = true).out.trim()
+
+      expect(out.contains("Explanation"))
+    }
+  }
+}

modules/options/src/main/scala/scala/build/actionable/ActionablePreprocessor.scala

@@ -16,7 +16,6 @@ object ActionablePreprocessor {
       .map(handler => handler.createActionableDiagnostics(options))
       .sequence
       .left.map(CompositeBuildException(_))
-      .map((v: Seq[Seq[Any]]) => v.flatten)
-      .asInstanceOf[Either[BuildException, Seq[ActionableDiagnostic]]]
+      .map(_.flatten)
 
 }