Relete covariance from Reader

src/main/scala/io/moia/protos/teleproto/Reader.scala

@@ -31,7 +31,7 @@ import scala.util.Try
 /** Provides reading of a generated Protocol Buffers model into a business model.
   */
 @implicitNotFound("No Protocol Buffers mapper from type ${P} to ${M} was found. Try to implement an implicit Reader for this type.")
-trait Reader[-P, +M] {
+trait Reader[P, M] {
 
   /** Returns the read business model or an error message.
     */
@@ -150,6 +150,13 @@ object Reader extends LowPriorityReads {
       PbSuccess((Duration(protobuf.seconds, SECONDS) + Duration(protobuf.nanos.toLong, NANOSECONDS)).toCoarsest)
   }
 
+  /** Transforms a ScalaPB duration into a Scala concurrent duration.
+    */
+  implicit object DurationReader extends Reader[PBDuration, Duration] {
+    def read(protobuf: PBDuration): PbResult[FiniteDuration] =
+      PbSuccess((Duration(protobuf.seconds, SECONDS) + Duration(protobuf.nanos.toLong, NANOSECONDS)).toCoarsest)
+  }
+
   /** Transforms a string into a UUID.
     */
   implicit object UUIDReader extends Reader[String, UUID] {

src/main/scala/io/moia/protos/teleproto/WriterImpl.scala

@@ -69,12 +69,13 @@ class WriterImpl(val c: blackbox.Context) extends FormatImpl {
     // look for an implicit writer
     val writerType = appliedType(c.weakTypeTag[Writer[_, _]].tpe, modelType, protobufType)
 
-    val existingWriter = try {
-      c.inferImplicitValue(writerType)
-    } catch {
-      // Return EmptyTree in case of errors
-      case _: Throwable => EmptyTree
-    }
+    val existingWriter =
+      try {
+        c.inferImplicitValue(writerType)
+      } catch {
+        // Return EmptyTree in case of errors
+        case _: Throwable => EmptyTree
+      }
 
     // "ask" for the implicit writer or use the found one
     def ask: Compiled = (compileInner(q"implicitly[$writerType]"), Compatibility.full)