Fix swallowing of warnings

If the span of an error message is too long (e.g., for a huge object definition), some warnings will
be swallowed.

Author: liufengyun

compiler/src/dotty/tools/dotc/transform/init/Objects.scala

@@ -252,7 +252,7 @@ object Objects:
           val joinedTrace = data.pendingTraces.slice(index + 1, data.checkingObjects.size).foldLeft(pendingTrace) { (a, acc) => acc ++ a }
           val callTrace = Trace.buildStacktrace(joinedTrace, "Calling trace:\n")
           val cycle = data.checkingObjects.slice(index, data.checkingObjects.size)
-          val pos = clazz.defTree
+          val pos = clazz.defTree.sourcePos.focus
           report.warning("Cyclic initialization: " + cycle.map(_.klass.show).mkString(" -> ") + " -> " + clazz.show + ". " + callTrace, pos)
         end if
         data.checkingObjects(index)

compiler/src/dotty/tools/dotc/transform/init/Trace.scala

@@ -49,7 +49,12 @@ object Trace:
           val code = SyntaxHighlighting.highlight(pos.lineContent.trim.nn)
           i"$code\t$loc"
         else
-          tree.show
+          tree match
+            case defDef: DefTree =>
+              // The definition can be huge, avoid printing the whole definition.
+              defDef.symbol.show
+            case _ =>
+              tree.show
       val positionMarkerLine =
         if pos.exists && pos.source.exists then
           positionMarker(pos)