Fix staging level tracking in Transformer

Author: nicolasstucki

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

@@ -17,6 +17,7 @@ import annotation.unchecked.uncheckedVariance
 import annotation.constructorOnly
 import compiletime.uninitialized
 import Decorators._
+import staging.StagingLevel.*
 
 object Trees {
 
@@ -1551,9 +1552,9 @@ object Trees {
               val trees1 = transform(trees)
               if (trees1 eq trees) tree else Thicket(trees1)
             case tree @ Quote(body) =>
-              cpy.Quote(tree)(transform(body))
+              cpy.Quote(tree)(transform(body)(using quoteContext))
             case tree @ Splice(expr) =>
-              cpy.Splice(tree)(transform(expr))
+              cpy.Splice(tree)(transform(expr)(using spliceContext))
             case tree @ Hole(_, _, args, content, tpt) =>
               cpy.Hole(tree)(args = transform(args), content = transform(content), tpt = transform(tpt))
             case _ =>

compiler/src/dotty/tools/dotc/transform/Splicing.scala

@@ -111,17 +111,13 @@ class Splicing extends MacroTransform:
 
     override def transform(tree: tpd.Tree)(using Context): tpd.Tree =
       tree match
-        case tree: Splice =>
-          if level > 1 then
-            val expr1 = super.transform(tree.expr)(using spliceContext)
-            cpy.Splice(tree)(expr1)
-          else
-            val holeIdx = numHoles
-            numHoles += 1
-            val splicer = SpliceTransformer(ctx.owner, quotedDefs.contains)
-            val newSplicedCode1 = splicer.transformSplice(tree.expr, tree.tpe, holeIdx)(using spliceContext)
-            val newSplicedCode2 = Level0QuoteTransformer.transform(newSplicedCode1)(using spliceContext)
-            newSplicedCode2
+        case tree: Splice if level == 1 =>
+          val holeIdx = numHoles
+          numHoles += 1
+          val splicer = SpliceTransformer(ctx.owner, quotedDefs.contains)
+          val newSplicedCode1 = splicer.transformSplice(tree.expr, tree.tpe, holeIdx)(using spliceContext)
+          val newSplicedCode2 = Level0QuoteTransformer.transform(newSplicedCode1)(using spliceContext)
+          newSplicedCode2
         case tree: TypeDef if tree.symbol.hasAnnotation(defn.QuotedRuntime_SplicedTypeAnnot) =>
           val tp @ TypeRef(qual: TermRef, _) = tree.rhs.tpe.hiBound: @unchecked
           quotedDefs += tree.symbol
@@ -134,8 +130,6 @@ class Splicing extends MacroTransform:
               typeHoles.put(qual, hole)
               hole
           cpy.TypeDef(tree)(rhs = hole)
-        case Apply(Select(_: Quote, nme.apply),List(quotes)) =>
-          super.transform(tree)(using quoteContext)
         case _: Template =>
           for sym <- tree.symbol.owner.info.decls do
             quotedDefs += sym