Merge pull request #3653 from densh/si/8200

SI-8200 provide an identity liftable for trees

5 files changed, 28 insertions, 5 deletions

diff --git a/bincompat-backward.whitelist.conf b/bincompat-backward.whitelist.conf
index ae31c286f3..f9760b5c3f 100644
--- a/bincompat-backward.whitelist.conf
+++ b/bincompat-backward.whitelist.conf
@@ -102,6 +102,11 @@ filter {
         matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip3"
         problemName=IncompatibleMethTypeProblem
     },
+    // see SI-8200
+    {
+        matchName="scala.reflect.api.StandardLiftables#StandardLiftableInstances.liftTree"
+        problemName=MissingMethodProblem
+    },
     // see SI-8331
     {
         matchName="scala.reflect.api.Internals#ReificationSupportApi#SyntacticTypeAppliedExtractor.unapply"
diff --git a/bincompat-forward.whitelist.conf b/bincompat-forward.whitelist.conf
index a4cbac4887..b84417e04a 100644
--- a/bincompat-forward.whitelist.conf
+++ b/bincompat-forward.whitelist.conf
@@ -102,6 +102,15 @@ filter {
         matchName="scala.collection.mutable.ArrayOps#ofDouble.unzip3"
         problemName=IncompatibleMethTypeProblem
     },
+    // see SI-8200
+    {
+        matchName="scala.reflect.api.Liftables#Liftable.liftTree"
+        problemName=MissingMethodProblem
+    },
+    {
+        matchName="scala.reflect.api.StandardLiftables#StandardLiftableInstances.liftTree"
+        problemName=MissingMethodProblem
+    },
     // see SI-8331 
     {
         matchName="scala.reflect.api.Internals#ReificationSupportApi.SyntacticSelectType"
diff --git a/src/reflect/scala/reflect/api/StandardLiftables.scala b/src/reflect/scala/reflect/api/StandardLiftables.scala
index af11de46ce..66ac62cc9e 100644
--- a/src/reflect/scala/reflect/api/StandardLiftables.scala
+++ b/src/reflect/scala/reflect/api/StandardLiftables.scala
@@ -27,6 +27,7 @@ trait StandardLiftables { self: Universe =>
       callScala(stdnme.Symbol)(Literal(Constant(v.name)) :: Nil)
     }
 
+    implicit def liftTree[T <: Tree]: Liftable[T]              = Liftable { identity }
     implicit def liftName[T <: Name]: Liftable[T]              = Liftable { name => Ident(name) }
     implicit def liftExpr[T <: Expr[_]]: Liftable[T]           = Liftable { expr => expr.tree }
     implicit def liftType[T <: Type]: Liftable[T]              = Liftable { tpe => TypeTree(tpe) }
diff --git a/test/files/scalacheck/quasiquotes/ErrorProps.scala b/test/files/scalacheck/quasiquotes/ErrorProps.scala
index 9433965935..9137fe17d8 100644
--- a/test/files/scalacheck/quasiquotes/ErrorProps.scala
+++ b/test/files/scalacheck/quasiquotes/ErrorProps.scala
@@ -9,9 +9,10 @@ object ErrorProps extends QuasiquoteProperties("errors") {
     """)
 
   property("can't unquote with given rank") = fails(
-    "Can't unquote List[reflect.runtime.universe.Ident], consider using ..",
+    "Can't unquote List[StringBuilder], consider using .. or providing an implicit instance of Liftable[List[StringBuilder]]",
     """
-      val xs = List(q"x", q"x")
+      import java.lang.StringBuilder
+      val xs: List[StringBuilder] = Nil
       q"$xs"
     """)
 
@@ -71,9 +72,10 @@ object ErrorProps extends QuasiquoteProperties("errors") {
     """)
 
   property("use ... rank or provide liftable") = fails(
-    "Can't unquote List[List[reflect.runtime.universe.Ident]], consider using ...",
+    "Can't unquote List[List[StringBuilder]], consider using ... or providing an implicit instance of Liftable[List[List[StringBuilder]]]",
     """
-      val xs = List(List(q"x", q"x"))
+      import java.lang.StringBuilder
+      val xs: List[List[StringBuilder]] = Nil
       q"$xs"
     """)
 
diff --git a/test/files/scalacheck/quasiquotes/LiftableProps.scala b/test/files/scalacheck/quasiquotes/LiftableProps.scala
index 5d0eeb53c6..29fdea5c89 100644
--- a/test/files/scalacheck/quasiquotes/LiftableProps.scala
+++ b/test/files/scalacheck/quasiquotes/LiftableProps.scala
@@ -88,9 +88,10 @@ object LiftableProps extends QuasiquoteProperties("liftable") {
     assert(q"$const" ≈ q"0")
   }
 
+  val immutable = q"$scalapkg.collection.immutable"
+
   property("lift list variants") = test {
     val lst = List(1, 2)
-    val immutable = q"$scalapkg.collection.immutable"
     assert(q"$lst" ≈ q"$immutable.List(1, 2)")
     assert(q"f(..$lst)" ≈ q"f(1, 2)")
     val llst = List(List(1), List(2))
@@ -98,6 +99,11 @@ object LiftableProps extends QuasiquoteProperties("liftable") {
     assert(q"f(...$llst)" ≈ q"f(1)(2)")
   }
 
+  property("lift list of tree") = test {
+    val lst = List(q"a", q"b")
+    assert(q"$lst" ≈ q"$immutable.List(a, b)")
+  }
+
   property("lift tuple") = test {
     assert(q"${(1, 2)}" ≈ q"(1, 2)")
     assert(q"${(1, 2, 3)}" ≈ q"(1, 2, 3)")