Fix #5119: Get underlying argument for synthetic local values

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

@@ -942,11 +942,14 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
     }
   }
 
-  /** Map Inlined nodes and InlineProxy references to underlying arguments */
+  /** Map Inlined nodes, InlineProxy references and Synthetic val references to underlying arguments */
   object mapToUnderlying extends TreeMap {
     override def transform(tree: Tree)(implicit ctx: Context): Tree = tree match {
-      case tree: Ident if tree.symbol.is(InlineProxy) =>
-        tree.symbol.defTree.asInstanceOf[ValOrDefDef].rhs.underlyingArgument
+      case tree: Ident if tree.symbol.is(InlineProxy) || (tree.symbol.is(Synthetic) && !tree.symbol.owner.isClass) =>
+        tree.symbol.defTree match {
+          case defTree: ValOrDefDef => defTree.rhs.underlyingArgument
+          case _ => tree
+        }
       case Inlined(_, _, arg) =>
         arg.underlyingArgument
       case tree =>

compiler/test/dotc/run-test-pickling.blacklist

@@ -20,6 +20,7 @@ i4803d
 i4803e
 i4803f
 i4947b
+i5119
 implicitShortcut
 lazy-implicit-lists.scala
 lazy-implicit-nums.scala

tests/run/i5119.check

@@ -0,0 +1,2 @@
+Term.Select(Term.Apply(Term.Select(Term.New(TypeTree.TypeIdent("StringContextOps")), "<init>", Some(Signature(List(scala.Function0), Macro$.StringContextOps))), List(Term.Apply(Term.Select(Term.Select(Term.Select(Term.Ident("_root_"), "scala", None), "StringContext", None), "apply", Some(Signature(List(scala.collection.Seq), scala.StringContext))), List(Term.Typed(Term.Repeated(List(Term.Literal(Constant.String("Hello World ")), Term.Literal(Constant.String("!")))), TypeTree.Synthetic()))))), "inline$sc", Some(Signature(Nil, scala.StringContext)))
+Term.Typed(Term.Repeated(List(Term.Literal(Constant.Int(1)))), TypeTree.Synthetic())

tests/run/i5119/Macro_1.scala

@@ -0,0 +1,13 @@
+import scala.quoted._
+import scala.tasty.Tasty
+
+object Macro {
+  class StringContextOps(sc: => StringContext) {
+    inline def ff(args: => Any*): String = ~Macro.impl('(sc), '(args))
+  }
+  implicit inline def XmlQuote(sc: => StringContext): StringContextOps = new StringContextOps(sc)
+  def impl(sc: Expr[StringContext], args: Expr[Seq[Any]])(implicit tasty: Tasty): Expr[String] = {
+    import tasty._
+    (sc.toTasty.underlyingArgument.show + "\n" + args.toTasty.underlyingArgument.show).toExpr
+  }
+}

tests/run/i5119/Main_2.scala

@@ -0,0 +1,8 @@
+
+object Test {
+  import Macro._
+
+  def main(args: Array[String]): Unit = {
+    println(ff"Hello World ${1}!")
+  }
+}

tests/run/xml-interpolation/Test_2.scala

@@ -2,8 +2,8 @@ import XmlQuote._
 
 object Test {
   def main(args: Array[String]): Unit = {
-    // TODO: enable once #5119 is fixed
-    // assert(xml"Hello Allan!" == Xml("Hello Allan!", Nil))
+
+    assert(xml"Hello Allan!" == Xml("Hello Allan!", Nil))
 
     val name = new Object{}
     assert(xml"Hello $name!" == Xml("Hello ??!", List(name)))