1 files changed, 76 insertions, 0 deletions
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
new file mode 100644
index 000000000..d15c1d2f1
--- /dev/null
+++ b/src/dotty/tools/dotc/reporting/diagnostic/MessageContainer.scala
@@ -0,0 +1,76 @@
+package dotty.tools
+package dotc
+package reporting
+package diagnostic
+
+import util.SourcePosition
+import core.Contexts.Context
+
+import java.util.Optional
+
+object MessageContainer {
+  val nonSensicalStartTag = "<nonsensical>"
+  val nonSensicalEndTag = "</nonsensical>"
+
+  implicit class MessageContext(val c: Context) extends AnyVal {
+    def shouldExplain(cont: MessageContainer): Boolean = {
+      implicit val ctx: Context = c
+      cont.explanation match {
+        case "" => false
+        case _ => ctx.settings.explain.value
+      }
+    }
+  }
+}
+
+class MessageContainer(
+  msgFn: => Message,
+  val pos: SourcePosition,
+  val level: Int,
+  val kind: String,
+  val explanation: String
+) extends Exception with interfaces.Diagnostic {
+  import MessageContainer._
+  private var myMsg: String = null
+  private var myIsNonSensical: Boolean = false
+  private var myContained: Message = null
+
+  override def position: Optional[interfaces.SourcePosition] =
+    if (pos.exists && pos.source.exists) Optional.of(pos) else Optional.empty()
+
+  /** The message to report */
+  def message: String = {
+    if (myMsg == null) {
+      myMsg = msgFn.msg
+      if (myMsg.contains(nonSensicalStartTag)) {
+        myIsNonSensical = true
+        // myMsg might be composed of several d"..." invocations -> nested
+        // nonsensical tags possible
+        myMsg =
+          myMsg
+          .replaceAllLiterally(nonSensicalStartTag, "")
+          .replaceAllLiterally(nonSensicalEndTag, "")
+      }
+    }
+    myMsg
+  }
+
+  def contained: Message = {
+    if (myContained == null)
+      myContained = msgFn
+
+    myContained
+  }
+
+  /** A message is non-sensical if it contains references to <nonsensical>
+   *  tags.  Such tags are inserted by the error diagnostic framework if a
+   *  message contains references to internally generated error types. Normally
+   *  we want to suppress error messages referring to types like this because
+   *  they look weird and are normally follow-up errors to something that was
+   *  diagnosed before.
+   */
+  def isNonSensical = { message; myIsNonSensical }
+
+  override def toString = s"$getClass at $pos: ${message}"
+  override def getMessage() = message
+}