Add Problem#rendered to customize how problems are shown

Dotty has its own logic for displaying problems with the proper file
path, position, and caret, but if we store this information in
Problem#message we end up with duplicated information in the output
since Zinc will prepend/append similar things (see
sbt.internal.inc.ProblemStringFormats). So far, we worked around this in
Dotty by using an empty position in the sbt bridge reporter, but this
means that crucial semantic information that could be used by a Build
Server Protocol implementation and other tools is lost. This commit
allows us to avoid by adding an optional `rendered` field to `Problem`:
when this field is set, its value controls what the user sees, otherwise
we fallback to the default behavior (the logic to do this will be added to
Zinc after this PR is merged and a new release of sbt-util is made).

build.sbt

@@ -124,8 +124,9 @@ lazy val utilLogging = (project in internalPath / "util-logging")
       exclude[DirectMissingMethodProblem]("sbt.internal.util.SuccessEvent.copy*"),
       exclude[DirectMissingMethodProblem]("sbt.internal.util.TraceEvent.copy*"),
       exclude[DirectMissingMethodProblem]("sbt.internal.util.StringEvent.copy*"),
-      // Private final class constructor changed
+      // Private final class constructors changed
       exclude[DirectMissingMethodProblem]("sbt.util.InterfaceUtil#ConcretePosition.this"),
+      exclude[DirectMissingMethodProblem]("sbt.util.InterfaceUtil#ConcreteProblem.this"),
     ),
   )
   .configure(addSbtIO)

internal/util-interface/src/main/java/xsbti/Problem.java

@@ -3,10 +3,20 @@
  */
 package xsbti;
 
+import java.util.Optional;
+
 public interface Problem
 {
 	String category();
 	Severity severity();
 	String message();
 	Position position();
+
+  // Default value to avoid breaking binary compatibility
+  /**
+   * If present, the string shown to the user when displaying this Problem.
+   * Otherwise, the Problem will be shown in an implementation-defined way
+   * based on the values of its other fields.
+   */
+  default Optional<String> rendered() { return Optional.empty(); }
 }

internal/util-logging/src/main/contraband/interface.contra.txt

@@ -29,4 +29,5 @@ type Problem {
   severity: Severity!
   message: String!
   position: Position!
+  rendered: String
 }

internal/util-logging/src/main/scala/sbt/internal/util/codec/ProblemFormats.scala

@@ -4,8 +4,8 @@
 package sbt.internal.util.codec
 
 import xsbti.{ Problem, Severity, Position }
-import sbt.util.InterfaceUtil.problem
 import _root_.sjsonnew.{ deserializationError, Builder, JsonFormat, Unbuilder }
+import java.util.Optional
 
 trait ProblemFormats { self: SeverityFormats with PositionFormats with sjsonnew.BasicJsonProtocol =>
   implicit lazy val ProblemFormat: JsonFormat[Problem] = new JsonFormat[Problem] {
@@ -13,12 +13,20 @@ trait ProblemFormats { self: SeverityFormats with PositionFormats with sjsonnew.
       jsOpt match {
         case Some(js) =>
           unbuilder.beginObject(js)
-          val category = unbuilder.readField[String]("category")
+          val category0 = unbuilder.readField[String]("category")
-          val severity = unbuilder.readField[Severity]("severity")
+          val severity0 = unbuilder.readField[Severity]("severity")
-          val message = unbuilder.readField[String]("message")
+          val message0 = unbuilder.readField[String]("message")
-          val position = unbuilder.readField[Position]("position")
+          val position0 = unbuilder.readField[Position]("position")
+          val rendered0 = unbuilder.readField[Optional[String]]("rendered")
+
           unbuilder.endObject()
-          problem(category, position, message, severity)
+          new Problem {
+            override val category = category0
+            override val position = position0
+            override val message = message0
+            override val severity = severity0
+            override val rendered = rendered0
+          }
         case None =>
           deserializationError("Expected JsObject but found None")
       }
@@ -29,6 +37,7 @@ trait ProblemFormats { self: SeverityFormats with PositionFormats with sjsonnew.
       builder.addField("severity", obj.severity)
       builder.addField("message", obj.message)
       builder.addField("position", obj.position)
+      builder.addField("rendered", obj.rendered)
       builder.endObject()
     }
   }

internal/util-logging/src/main/scala/sbt/util/InterfaceUtil.scala

@@ -89,8 +89,16 @@ object InterfaceUtil {
                          endLine0,
                          endColumn0)
 
+  @deprecated("Use the overload of this method with more arguments", "1.2.2")
   def problem(cat: String, pos: Position, msg: String, sev: Severity): Problem =
-    new ConcreteProblem(cat, pos, msg, sev)
+    problem(cat, pos, msg, sev, None)
+
+  def problem(cat: String,
+              pos: Position,
+              msg: String,
+              sev: Severity,
+              rendered: Option[String]): Problem =
+    new ConcreteProblem(cat, pos, msg, sev, rendered)
 
   private final class ConcreteT2[A1, A2](a1: A1, a2: A2) extends T2[A1, A2] {
     val get1: A1 = a1
@@ -144,12 +152,14 @@ object InterfaceUtil {
       cat: String,
       pos: Position,
       msg: String,
-      sev: Severity
+      sev: Severity,
+      rendered0: Option[String]
   ) extends Problem {
     val category = cat
     val position = pos
     val message = msg
     val severity = sev
+    override val rendered = o2jo(rendered0)
     override def toString = s"[$severity] $pos: $message"
   }
 }

internal/util-logging/src/main/scala/sbt/util/Logger.scala

@@ -117,6 +117,7 @@ object Logger {
       sourceFile0
     )
 
+  @deprecated("Use InterfaceUtil.problem", "1.2.2")
   def problem(cat: String, pos: Position, msg: String, sev: Severity): Problem =
     InterfaceUtil.problem(cat, pos, msg, sev)
 }