Cleanup code

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/StagingContext.scala

@@ -32,10 +32,14 @@ object StagingContext {
     ctx.fresh.setProperty(QuotationLevel, level - 1)
 
   def popQuoteContext()(implicit ctx: Context): (Option[tpd.Tree], Context) =
-    assert(level >= 0)
-    val head = ctx.property(QuotationContexts).flatMap(_.headOption)
     val ctx1 = ctx.fresh.setProperty(QuotationLevel, level - 1)
-                        .setProperty(QuotationContexts, ctx.property(QuotationContexts).map(_.drop(1)).getOrElse(Nil))
+    val head =
+      ctx.property(QuotationContexts) match
+        case Some(x :: xs) =>
+          ctx1.setProperty(QuotationContexts, xs)
+          Some(x)
+        case _ =>
+          None // Splice at level 0 or lower
     (head, ctx1)
 }
 

compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala

@@ -91,21 +91,19 @@ trait QuotesAndSplices {
         markAsMacro(ctx)
       }
 
-      val (topQuoteContext, ctx1) =
-        if level < 0 then (None, spliceContext)
-        else  popQuoteContext()
+      val (outerQctx, ctx1) = popQuoteContext()
 
       // Explicitly provide the given QuoteContext of the splice.
       //  * Avoids leaking implementation details of scala.internal.quoted.CompileTime.exprSplice,
       //    such as exprSplice taking a ?=> function argument
       //  * Provide meaningful names for QuoteContext synthesized by within `${ ... }`
-      val qctxParamName = NameKinds.UniqueName.fresh(s"qctx${level - 1}_".toTermName)
-      val qctxParamTpe = topQuoteContext match {
+      //  * If within a quote, provide a QuoteContext is linked typewise with the outer QuoteContext
+      val qctxParamName = NameKinds.UniqueName.fresh(s"qctx${if level > 0 then level - 1 else ""}_".toTermName)
+      val qctxParamTpe = outerQctx match {
         case Some(qctxRef) => qctxRef.tpe.select("NestedContext".toTypeName)
-        case _ => defn.QuoteContextClass.typeRef
+        case _ => defn.QuoteContextClass.typeRef // splice at level 0 (or lower)
       }
       val qctxParamTpt = untpd.TypedSplice(TypeTree(qctxParamTpe))
-
       val qctxParam = untpd.makeParameter(qctxParamName, qctxParamTpt, untpd.Modifiers(Given))
       val expr = untpd.Function(List(qctxParam), tree.expr).withSpan(tree.span)