Merge pull request #1881 from dotty-staging/add-structural-select

Implement structural type member access

7 files changed, 117 insertions, 7 deletions

diff --git a/tests/neg/structural.scala b/tests/neg/structural.scala
new file mode 100644
index 000000000..aab52b2cb
--- /dev/null
+++ b/tests/neg/structural.scala
@@ -0,0 +1,11 @@
+object Test3 {
+  import scala.reflect.Selectable.reflectiveSelectable
+  def g(x: { type T ; def t: T ; def f(a: T): Boolean }) = x.f(x.t) // error: no ClassTag for x.T
+  g(new { type T = Int; def t = 4; def f(a:T) = true })
+  g(new { type T = Any; def t = 4; def f(a:T) = true })
+  val y: { type T = Int; def t = 4; def f(a:T) = true }
+    = new { type T = Int; def t = 4; def f(a:T) = true }
+
+  def h(x: { def f[T](a: T): Int }) = x.f[Int](4) // error: polymorphic refinement method ... no longer allowed
+
+}
diff --git a/tests/neg/zoo.scala b/tests/neg/zoo.scala
index 19efcc1d7..1674548e8 100644
--- a/tests/neg/zoo.scala
+++ b/tests/neg/zoo.scala
@@ -7,19 +7,19 @@ type Grass = {
 }
 type Animal = {
   type Food
-  def eats(food: Food): Unit   // error
-  def gets: Food               // error
+  def eats(food: Food): Unit
+  def gets: Food
 }
 type Cow = {
   type IsMeat = Any
   type Food <: Grass
-  def eats(food: Grass): Unit  // error
-  def gets: Grass              // error
+  def eats(food: Grass): Unit
+  def gets: Grass
 }
 type Lion = {
   type Food = Meat
-  def eats(food: Meat): Unit   // error
-  def gets: Meat               // error
+  def eats(food: Meat): Unit
+  def gets: Meat
 }
 def newMeat: Meat = new {
   type IsMeat = Any
@@ -40,5 +40,5 @@ def newLion: Lion = new {
 }
 val milka = newCow
 val leo = newLion
-leo.eats(milka) // structural select not supported
+leo.eats(milka)  // error: no projector found
 }
diff --git a/tests/pos/i1866.scala b/tests/pos/i1866.scala
new file mode 100644
index 000000000..918d2e182
--- /dev/null
+++ b/tests/pos/i1866.scala
@@ -0,0 +1,5 @@
+import scala.reflect.Selectable.reflectiveSelectable
+object Test {
+  def f(g: { val update: Unit }) = g.update
+  def main(update: Array[String]) = {}
+}
diff --git a/tests/pos/zoo2.scala b/tests/pos/zoo2.scala
new file mode 100644
index 000000000..06210fe67
--- /dev/null
+++ b/tests/pos/zoo2.scala
@@ -0,0 +1,45 @@
+import scala.reflect.Selectable.reflectiveSelectable
+object Test {
+type Meat = {
+  type IsMeat = Any
+}
+type Grass = {
+  type IsGrass = Any
+}
+type Animal = {
+  type Food
+  def eats(food: Food): Unit
+  def gets: Food
+}
+type Cow = {
+  type IsMeat = Any
+  type Food <: Grass
+  def eats(food: Grass): Unit
+  def gets: Grass
+}
+type Lion = {
+  type Food = Meat
+  def eats(food: Meat): Unit
+  def gets: Meat
+}
+def newMeat: Meat = new {
+  type IsMeat = Any
+}
+def newGrass: Grass = new {
+  type IsGrass = Any
+}
+def newCow: Cow = new {
+  type IsMeat = Any
+  type Food = Grass
+  def eats(food: Grass) = ()
+  def gets = newGrass
+}
+def newLion: Lion = new {
+  type Food = Meat
+  def eats(food: Meat) = ()
+  def gets = newMeat
+}
+val milka = newCow
+val leo = newLion
+leo.eats(milka)
+}
diff --git a/tests/run/structural.scala b/tests/run/structural.scala
new file mode 100644
index 000000000..0f18f4579
--- /dev/null
+++ b/tests/run/structural.scala
@@ -0,0 +1,25 @@
+case class Record(elems: (String, Any)*) extends Selectable {
+  def selectDynamic(name: String): Any = elems.find(_._1 == name).get._2
+}
+
+object Test {
+  import scala.reflect.Selectable.reflectiveSelectable
+
+  def f(closeable: { def close(): Unit }) =
+    closeable.close()
+
+  type RN = Record { val name: String; val age: Int }
+
+  def g(r: RN) = r.name
+
+  val rr: RN = Record("name" -> "Bob", "age" -> 42).asInstanceOf[RN]
+
+  def main(args: Array[String]): Unit = {
+    f(new java.io.PrintStream("foo"))
+    assert(g(rr) == "Bob")
+
+    val s: { def concat(s: String): String } = "abc"
+    assert(s.concat("def") == "abcdef")
+  }
+}
+
diff --git a/tests/run/structuralNoSuchMethod.check b/tests/run/structuralNoSuchMethod.check
new file mode 100644
index 000000000..20576fc9c
--- /dev/null
+++ b/tests/run/structuralNoSuchMethod.check
@@ -0,0 +1 @@
+no such method
diff --git a/tests/run/structuralNoSuchMethod.scala b/tests/run/structuralNoSuchMethod.scala
new file mode 100644
index 000000000..476d7ed82
--- /dev/null
+++ b/tests/run/structuralNoSuchMethod.scala
@@ -0,0 +1,23 @@
+import scala.reflect.Selectable.reflectiveSelectable
+
+/** Demonstrates limitation of structural method dispatch (in Scala 2.x and dotty).
+ *  The method must be defined at exactly the argument types given in the structural type;
+ *  Generic instantiation is not possible.
+ */
+object Test {
+  type T = { def f(x: String, y: String): String }
+
+  class C[X] {
+    def f(x: X, y: String): String = "f1"
+  }
+
+  val x: T = new C[String]
+
+  def main(args: Array[String]) =
+    try println(x.f("", ""))  // throws NoSuchMethodException
+    catch {
+      case ex: NoSuchMethodException =>
+        println("no such method")
+    }
+
+}