Improve output of -Xprint-inline (#16376)

Used to debug #16374

Author: nicolasstucki

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -523,9 +523,10 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
       case SeqLiteral(elems, elemtpt) =>
         "[" ~ toTextGlobal(elems, ",") ~ " : " ~ toText(elemtpt) ~ "]"
       case tree @ Inlined(call, bindings, body) =>
-        (("/* inlined from " ~ (if (call.isEmpty) "outside" else toText(call)) ~ " */ ") `provided`
-          !homogenizedView && ctx.settings.XprintInline.value) ~
-          (if bindings.isEmpty then toText(body) else blockText(bindings :+ body))
+        val bodyText = if bindings.isEmpty then toText(body) else blockText(bindings :+ body)
+        if homogenizedView || !ctx.settings.XprintInline.value then bodyText
+        else if call.isEmpty then stringText("{{") ~ stringText("/* inlined from outside */") ~ bodyText ~ stringText("}}")
+        else keywordText("{{") ~ keywordText("/* inlined from ") ~ toText(call) ~ keywordText(" */") ~ bodyText ~ keywordText("}}")
       case tpt: untpd.DerivedTypeTree =>
         "<derived typetree watching " ~ tpt.watched.showSummary() ~ ">"
       case TypeTree() =>