Fix #9150: Dealias reference to singleton

Author: nicolasstucki

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

@@ -421,7 +421,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       t
   }
 
-  def singleton(tp: Type)(implicit ctx: Context): Tree = tp match {
+  def singleton(tp: Type)(implicit ctx: Context): Tree = tp.dealias match {
     case tp: TermRef => ref(tp)
     case tp: ThisType => This(tp.cls)
     case tp: SkolemType => singleton(tp.narrow)

tests/pos/i9150-a.scala

@@ -0,0 +1,4 @@
+import scala.compiletime.erasedValue
+
+inline def fooErased[T] = inline erasedValue[T] match { case _ => }
+val f = fooErased[EmptyTuple]

tests/pos/i9150-b.scala

@@ -0,0 +1,7 @@
+import scala.compiletime.erasedValue
+
+type Foo = Foo.type
+object Foo
+
+inline def fooErased[T] = inline erasedValue[T] match { case _ => }
+val f = fooErased[Foo]