Avoid double traversal of tree

Author: nicolasstucki

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

@@ -89,10 +89,7 @@ class Inlining extends MacroTransform {
         case _ if Inliner.isInlineable(tree) && !tree.tpe.widen.isInstanceOf[MethodOrPoly] && StagingContext.level == 0 =>
           val tree1 = super.transform(tree)
           if tree1.tpe.isError then tree1
-          else
-            val inlined = Inliner.inlineCall(tree1)
-            if tree1 eq inlined then inlined
-            else transform(inlined) // TODO can this be removed if `needsStaging` is set in `Inliner`?
+          else Inliner.inlineCall(tree1)
         case _: GenericApply if tree.symbol.isQuote =>
           ctx.compilationUnit.needsStaging = true
           super.transform(tree)(using StagingContext.quoteContext)

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

@@ -1284,7 +1284,7 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
       super.typedValDef(vdef1, sym)
 
     override def typedApply(tree: untpd.Apply, pt: Type)(using Context): Tree =
-      constToLiteral(betaReduce(super.typedApply(tree, pt))) match {
+      val res = constToLiteral(betaReduce(super.typedApply(tree, pt))) match {
         case res: Apply if res.symbol == defn.QuotedRuntime_exprSplice
                         && level == 0
                         && !suppressInline =>
@@ -1293,6 +1293,12 @@ class Inliner(call: tpd.Tree, rhsToInline: tpd.Tree)(using Context) {
         case res =>
           inlineIfIsNestedInlineCall(res)
       }
+      if res.symbol == defn.QuotedRuntime_exprQuote then
+        ctx.compilationUnit.needsStaging = true
+      res
+
+    override def typedTypeApply(tree: untpd.TypeApply, pt: Type)(using Context): Tree =
+      inlineIfIsNestedInlineCall(constToLiteral(betaReduce(super.typedTypeApply(tree, pt))))
 
     override def typedMatchFinish(tree: untpd.Match, sel: Tree, wideSelType: Type, cases: List[untpd.CaseDef], pt: Type)(using Context) =
       if (!tree.isInline || ctx.owner.isInlineMethod) // don't reduce match of nested inline method yet