Define spans of tpd.desugarIdentPrefix and TreeInfo.qualifier

Set the spans to the span of the original tree.

Author: odersky

compiler/src/dotty/tools/dotc/ast/TreeInfo.scala

@@ -852,12 +852,13 @@ trait TypedTreeInfo extends TreeInfo[Type] { self: Trees.Instance[Type] =>
   }
 
   /** The qualifier part of a Select or Ident.
-   *  For an Ident, this is the `This` of the current class.
+   *  For an Ident, this is the `This` of the current class, with the span of
+   *  the original tree.
    */
   def qualifier(tree: Tree)(using Context): Tree = tree match {
     case Select(qual, _) => qual
     case tree: Ident => desugarIdentPrefix(tree)
-    case _ => This(ctx.owner.enclosingClass.asClass)
+    case _ => This(ctx.owner.enclosingClass.asClass).withSpan(tree.span)
   }
 
   /** Is this a (potentially applied) selection of a member of a structural type

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -1403,13 +1403,14 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   /** Recover identifier prefix (e.g. this) if it exists */
   def desugarIdentPrefix(tree: Ident)(using Context): Tree = tree.tpe match {
     case TermRef(prefix: TermRef, _) =>
-      prefix.info match
-        case mt: MethodType if mt.paramInfos.isEmpty && mt.resultType.typeSymbol.is(Module) =>
-          ref(mt.resultType.typeSymbol.sourceModule)
-        case _ =>
-          ref(prefix)
+      { prefix.info match
+          case mt: MethodType if mt.paramInfos.isEmpty && mt.resultType.typeSymbol.is(Module) =>
+            ref(mt.resultType.typeSymbol.sourceModule)
+          case _ =>
+            ref(prefix)
+      }.withSpan(tree.span)
     case TermRef(prefix: ThisType, _) =>
-      This(prefix.cls)
+      This(prefix.cls).withSpan(tree.span)
     case _ =>
       EmptyTree
   }