Add DiagnosticRelatedInformation to compiler's interface

Author: prolativ

compiler/src/dotty/tools/dotc/reporting/Diagnostic.scala

@@ -9,7 +9,7 @@ import dotty.tools.dotc.core.Contexts._
 import dotty.tools.dotc.interfaces.Diagnostic.{ERROR, INFO, WARNING}
 import dotty.tools.dotc.util.SourcePosition
 
-import java.util.Optional
+import java.util.{Collections, Optional, List => JList}
 import scala.util.chaining._
 import core.Decorators.toMessage
 
@@ -100,6 +100,8 @@ class Diagnostic(
     if (pos.exists && pos.source.exists) Optional.of(pos) else Optional.empty()
   override def message: String =
     msg.message.replaceAll("\u001B\\[[;\\d]*m", "")
+  override def diagnosticRelatedInformation: JList[interfaces.DiagnosticRelatedInformation] =
+    Collections.emptyList()
 
   override def toString: String = s"$getClass at $pos: $message"
   override def getMessage(): String = message

interfaces/src/dotty/tools/dotc/interfaces/Diagnostic.java

@@ -1,6 +1,7 @@
 package dotty.tools.dotc.interfaces;
 
 import java.util.Optional;
+import java.util.List;
 
 /** A diagnostic is a message emitted during the compilation process.
  *
@@ -23,4 +24,7 @@ public interface Diagnostic {
   /** @return The position in a source file of the code that caused this diagnostic
    *  to be emitted. */
   Optional<SourcePosition> position();
+
+  /** @return A list of additional messages together with their code positions */
+  List<DiagnosticRelatedInformation> diagnosticRelatedInformation();
 }

interfaces/src/dotty/tools/dotc/interfaces/DiagnosticRelatedInformation.java

@@ -0,0 +1,6 @@
+package dotty.tools.dotc.interfaces;
+
+public interface DiagnosticRelatedInformation {
+  SourcePosition position();
+  String message();
+}