Add tests for specializing unobscured Func1 implementation

Author: felixmulder

compiler/test/dotty/tools/dotc/transform/SpecializeFunction1Tests.scala

@@ -12,6 +12,21 @@ class SpecializeFunction1Tests extends DottyBytecodeTest {
   import dotty.tools.backend.jvm.ASMConverters._
   import dotty.tools.backend.jvm.AsmNode._
 
+  protected def checkForBoxing(ins: List[Instruction], source: String): Unit = ins.foreach {
+    case Invoke(op, owner, name, desc, itf) =>
+      def error =
+        s"""|----------------------------------
+            |${ins.mkString("\n")}
+            |----------------------------------
+            |From code:
+            |$source
+            |----------------------------------""".stripMargin
+
+      assert(!owner.toLowerCase.contains("box"), s"Boxing instruction discovered in:\n$error")
+      assert(!name.toLowerCase.contains("box"), s"Boxing instruction discovered in:\n$error")
+    case _ => ()
+  }
+
   @Test def specializeParentIntToInt = {
     val source = """
                  |class Foo extends Function1[Int, Int] {
@@ -50,4 +65,30 @@ class SpecializeFunction1Tests extends DottyBytecodeTest {
       )
     }
   }
+
+  @Test def checkBoxingIntToInt = {
+    val source =
+      """|object Test {
+         |  class Func1 extends Function1[Int, Int] {
+         |    def apply(i: Int) = i + 1
+         |  }
+         |
+         |  (new Func1)(1)
+         |}""".stripMargin
+
+    checkBCode(source) { dir =>
+      import scala.collection.JavaConverters._
+      val clsIn = dir.lookupName("Test$.class", directory = false).input
+      val clsNode = loadClassNode(clsIn)
+      assert(clsNode.name == "Test$", s"inspecting wrong class: ${clsNode.name}")
+
+      clsNode.methods.asScala
+        .find(_.name == "<init>")
+        .map { m =>
+          checkForBoxing(instructionsFromMethod(m), source)
+        }
+        .getOrElse(assert(false, "Could not find constructor for object `Test`"))
+    }
+
+  }
 }