Fix scala#3847: Splice type splices in TypeTrees

Author: nicolasstucki

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

@@ -320,6 +320,10 @@ class ReifyQuotes extends MacroTransform {
             quotation(quotedTree, tree)
           case Select(body, _) if tree.symbol.isSplice =>
             splice(body, tree)
+          case tree: TypeTree if tree.tpe.typeSymbol.isSplice =>
+            // FIXME handle nested spliced type like TypeTree(List[t.unary_~])
+            val splicedType = tree.tpe.asInstanceOf[TypeRef].prefix.termSymbol
+            splice(ref(splicedType), tree)
           case Block(stats, _) =>
             val last = enteredSyms
             stats.foreach(markDef)

tests/run-with-compiler/i3847-b.check

@@ -0,0 +1,3 @@
+{
+  dotty.runtime.Arrays.newGenericArray[Int](3)(reflect.ClassTag.Int)
+}

tests/run-with-compiler/i3847-b.scala

@@ -0,0 +1,19 @@
+import dotty.tools.dotc.quoted.Runners._
+import scala.quoted._
+import scala.reflect.ClassTag
+
+object Arrays {
+  implicit def ArrayIsLiftable[T: Liftable](implicit t: Type[T], ct: Expr[ClassTag[T]]): Liftable[Array[List[T]]] = (arr: Array[List[T]]) => '{
+    new Array[List[~t]](~(arr.length: Expr[Int]))
+    // TODO add elements
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    import Arrays._
+    implicit val ct: Expr[ClassTag[Int]] = '(ClassTag.Int)
+    val arr: Expr[Array[List[Int]]] = Array[List[Int]](List(1, 2, 3))
+    println(arr.show)
+  }
+}

tests/run-with-compiler/i3847.check

@@ -0,0 +1,3 @@
+{
+  dotty.runtime.Arrays.newGenericArray[Int](3)(reflect.ClassTag.Int)
+}

tests/run-with-compiler/i3847.scala

@@ -0,0 +1,19 @@
+import dotty.tools.dotc.quoted.Runners._
+import scala.quoted._
+import scala.reflect.ClassTag
+
+object Arrays {
+  implicit def ArrayIsLiftable[T: Liftable](implicit t: Type[T], ct: Expr[ClassTag[T]]): Liftable[Array[T]] = (arr: Array[T]) => '{
+    new Array[~t](~(arr.length: Expr[Int]))(~ct)
+    // TODO add elements
+  }
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    import Arrays._
+    implicit val ct: Expr[ClassTag[Int]] = '(ClassTag.Int)
+    val arr: Expr[Array[Int]] = Array[Int](1, 2, 3)
+    println(arr.show)
+  }
+}