Better bad annotation file error reporting (#771)

* Propagate exceptions from JsonProtocol deserialization

* Add AnnotationFileNotFoundException for better error reporting

* Add AnnotationClassNotFoundException for better error reporting

* Better propagate JSON parsing errors

Also report the file if there is a error deserializing a JSON file

* Make exception for non-array JSON file more explicit

1 files changed, 17 insertions, 17 deletions

diff --git a/src/main/scala/firrtl/annotations/JsonProtocol.scala b/src/main/scala/firrtl/annotations/JsonProtocol.scala
index 5005ccb0..7b2617f5 100644
--- a/src/main/scala/firrtl/annotations/JsonProtocol.scala
+++ b/src/main/scala/firrtl/annotations/JsonProtocol.scala
@@ -2,7 +2,7 @@
 package firrtl
 package annotations
 
-import scala.util.Try
+import scala.util.{Try, Failure}
 
 import org.json4s._
 import org.json4s.native.JsonMethods._
@@ -13,18 +13,6 @@ import firrtl.ir._
 import firrtl.Utils.error
 
 object JsonProtocol {
-
-  // Helper for error messages
-  private def prettifyJsonInput(in: JsonInput): String = {
-    def defaultToString(base: String, obj: Any): String = s"$base@${obj.hashCode.toHexString}"
-    in match {
-      case FileInput(file) => file.toString
-      case StringInput(o) => defaultToString("String", o)
-      case ReaderInput(o) => defaultToString("Reader", o)
-      case StreamInput(o) => defaultToString("Stream", o)
-    }
-  }
-
   class TransformClassSerializer extends CustomSerializer[Class[_ <: Transform]](format => (
     { case JString(s) => Class.forName(s).asInstanceOf[Class[_ <: Transform]] },
     { case x: Class[_] => JString(x.getName) }
@@ -66,19 +54,31 @@ object JsonProtocol {
   def deserialize(in: JsonInput): Seq[Annotation] = deserializeTry(in).get
 
   def deserializeTry(in: JsonInput): Try[Seq[Annotation]] = Try({
-    def throwError() = throw new InvalidAnnotationFileException(prettifyJsonInput(in))
     val parsed = parse(in)
     val annos = parsed match {
       case JArray(objs) => objs
-      case _ => throwError()
+      case x => throw new InvalidAnnotationJSONException(
+        s"Annotations must be serialized as a JArray, got ${x.getClass.getSimpleName} instead!")
     }
     // Gather classes so we can deserialize arbitrary Annotations
     val classes = annos.map({
       case JObject(("class", JString(c)) :: tail) => c
-      case _ => throwError()
+      case obj => throw new InvalidAnnotationJSONException(s"Expected field 'class' not found! $obj")
     }).distinct
     val loaded = classes.map(Class.forName(_).asInstanceOf[Class[_ <: Annotation]])
     implicit val formats = jsonFormat(loaded)
     read[List[Annotation]](in)
-  })
+  }).recoverWith {
+    // Translate some generic errors to specific ones
+    case e: java.lang.ClassNotFoundException =>
+      Failure(new AnnotationClassNotFoundException(e.getMessage))
+    case e: org.json4s.ParserUtil.ParseException =>
+      Failure(new InvalidAnnotationJSONException(e.getMessage))
+  }.recoverWith { // If the input is a file, wrap in InvalidAnnotationFileException
+    case e => in match {
+      case FileInput(file) =>
+        Failure(new InvalidAnnotationFileException(file, e))
+      case _ => Failure(e)
+    }
+  }
 }