Merge pull request #6480 from dotty-staging/bootstrap-quoted-liftable

Use Dotty features in quoted.Liftable

Author: nicolasstucki

library/src-3.x/scala/quoted/Liftable.scala

@@ -0,0 +1,33 @@
+package scala.quoted
+
+import scala.runtime.quoted.Unpickler.liftedExpr
+
+/** A typeclass for types that can be turned to `quoted.Expr[T]`
+ *  without going through an explicit `'{...}` operation.
+ */
+abstract class Liftable[T] {
+  def toExpr(x: T): Expr[T]
+}
+
+/** Some liftable base types. To be completed with at least all types
+ *  that are valid Scala literals. The actual implementation of these
+ *  typed could be in terms of `ast.tpd.Literal`; the test `quotable.scala`
+ *  gives an alternative implementation using just the basic staging system.
+ */
+object Liftable {
+
+  implied for Liftable[Boolean] = new PrimitiveLifable
+  implied for Liftable[Short] = new PrimitiveLifable
+  implied for Liftable[Int] = new PrimitiveLifable
+  implied for Liftable[Long] = new PrimitiveLifable
+  implied for Liftable[Float] = new PrimitiveLifable
+  implied for Liftable[Double] = new PrimitiveLifable
+  implied for Liftable[Char] = new PrimitiveLifable
+  implied for Liftable[String] = new PrimitiveLifable
+  implied ClassIsLiftable[T] for Liftable[Class[T]] = new PrimitiveLifable // FIXME: annonymous implied with type parameter not working
+
+  private class PrimitiveLifable[T] extends Liftable[T] {
+    override def toExpr(x: T): Expr[T] = liftedExpr(x)
+  }
+
+}

library/src/scala/quoted/Liftable.scala

@@ -1,6 +1,5 @@
 import scala.quoted.Expr
 object Macro {
-  import quoted.Liftable.{IntIsLiftable => _}
   inline def foo(inline n: Int): Int = ${
     'n
   }

tests/pos-macros/quote-lift-inline-params/Macro_1.scala

@@ -1,5 +1,4 @@
 import scala.quoted.Expr
-import quoted.Liftable.{IntIsLiftable => _}
 object Macro {
   inline def foo(inline n: Int): Int = ${
     'n

tests/pos/quote-lift-inline-params-b.scala

@@ -7,7 +7,7 @@ object Test {
   {
     import Liftable._
 
-    '{ ${IntIsLiftable.toExpr(1)} }
+    '{ ${the[Liftable[Int]].toExpr(1)} }
 
     '{ ${1.toExpr} }