Box interpolated values as necessary

Box interpolated values for consistency in testing and to avoid runtime
checks for expressions of type Any.

Author: jcracknell

src/main/scala/com/typesafe/scalalogging/LoggerMacro.scala

@@ -239,17 +239,18 @@ private object LoggerMacro {
 
     message.tree match {
       case q"scala.StringContext.apply(..$parts).s(..$args)" =>
-        val messageFormat = parts.iterator.map({ case Literal(Constant(str: String)) => str })
+        val format = parts.iterator.map({ case Literal(Constant(str: String)) => str })
           // Emulate standard interpolator escaping
           .map(StringContext.treatEscapes)
           // Escape literal slf4j format anchors if the resulting call will require a format string
           .map(str => if (args.nonEmpty) str.replace("{}", "\\{}") else str)
           .mkString("{}")
 
-        (c.Expr(q"$messageFormat"), args map { arg =>
-          // Box interpolated AnyVals by explicitly getting the string representation
-          c.Expr[Any](if (arg.tpe <:< weakTypeOf[AnyVal]) q"$arg.toString" else arg)
-        })
+        val formatArgs = args map { arg =>
+          c.Expr[AnyRef](if (arg.tpe <:< weakTypeOf[AnyRef]) arg else q"$arg.asInstanceOf[_root_.scala.AnyRef]")
+        }
+
+        (c.Expr(q"$format"), formatArgs)
 
       case _ => (message, Seq.empty)
     }

src/test/scala/com/typesafe/scalalogging/LoggerSpec.scala

@@ -420,11 +420,18 @@ class LoggerSpec extends WordSpec with Matchers with MockitoSugar {
 
   "Logging a message using the standard string interpolator" should {
 
-    "call the underlying format method with the string representation of AnyVal arguments" in {
+    "call the underlying format method with boxed versions of value arguments" in {
       val f = fixture(_.isErrorEnabled, true)
       import f._
       logger.error(s"msg ${1}")
-      verify(underlying).error("msg {}", 1.toString)
+      verify(underlying).error("msg {}", 1.asInstanceOf[AnyRef])
+    }
+
+    "call the underlying format method with boxed versions of arguments of type Any" in {
+      val f = fixture(_.isErrorEnabled, true)
+      import f._
+      logger.error(s"msg ${1.asInstanceOf[Any]}")
+      verify(underlying).error("msg {}", 1.asInstanceOf[AnyRef])
     }
 
     "call the underlying format method escaping literal format anchors" in {