Do not throw NonFatal exceptions in annotation logging

If an annotation cannot be serialized by json4s, we should not throw
exceptions when doing trace-level logging.

2 files changed, 38 insertions, 4 deletions

diff --git a/src/main/scala/firrtl/Compiler.scala b/src/main/scala/firrtl/Compiler.scala
index 5a7dd4c8..6f921189 100644
--- a/src/main/scala/firrtl/Compiler.scala
+++ b/src/main/scala/firrtl/Compiler.scala
@@ -6,6 +6,8 @@ import logger._
 import java.io.Writer
 
 import scala.collection.mutable
+import scala.util.Try
+import scala.util.control.NonFatal
 
 import firrtl.annotations._
 import firrtl.ir.Circuit
@@ -211,7 +213,14 @@ private[firrtl] object Transform {
 
     logger.info(s"Form: ${after.form}")
     logger.trace(s"Annotations:")
-    logger.trace(JsonProtocol.serialize(remappedAnnotations))
+    logger.trace {
+      JsonProtocol.serializeTry(remappedAnnotations).recoverWith {
+        case NonFatal(e) =>
+          val msg = s"Exception thrown during Annotation serialization:\n  " +
+                    e.toString.replaceAll("\n", "\n  ")
+          Try(msg)
+      }.get
+    }
 
     logger.trace(s"Circuit:\n${after.circuit.serialize}")
     logger.info(s"======== Finished Transform $name ========\n")
diff --git a/src/test/scala/firrtlTests/annotationTests/JsonProtocolSpec.scala b/src/test/scala/firrtlTests/annotationTests/JsonProtocolSpec.scala
index 507c5291..d1bd1fb2 100644
--- a/src/test/scala/firrtlTests/annotationTests/JsonProtocolSpec.scala
+++ b/src/test/scala/firrtlTests/annotationTests/JsonProtocolSpec.scala
@@ -2,10 +2,12 @@
 
 package firrtlTests.annotationTests
 
-import firrtl.Parser
-import firrtl.annotations.{Annotation, JsonProtocol, NoTargetAnnotation}
+import firrtl._
+import firrtl.annotations.{JsonProtocol, NoTargetAnnotation}
 import firrtl.ir._
-import org.scalatest.{FlatSpec, Matchers, PropSpec}
+import firrtl.options.Dependency
+import _root_.logger.{Logger, LogLevel, LogLevelAnnotation}
+import org.scalatest.{FlatSpec, Matchers}
 
 case class AnAnnotation(
     info: Info,
@@ -18,6 +20,16 @@ case class AnAnnotation(
     groundType: GroundType
 ) extends NoTargetAnnotation
 
+class AnnoInjector extends Transform with DependencyAPIMigration {
+  override def optionalPrerequisiteOf = Dependency[ChirrtlEmitter] :: Nil
+  override def invalidates(a: Transform): Boolean = false
+  def execute(state: CircuitState): CircuitState = {
+    // Classes defined in method bodies can't be serialized by json4s
+    case class MyAnno(x: Int) extends NoTargetAnnotation
+    state.copy(annotations = MyAnno(3) +: state.annotations)
+  }
+}
+
 class JsonProtocolSpec extends FlatSpec with Matchers {
   "JsonProtocol" should "serialize and deserialize FIRRTL types" in {
 
@@ -40,4 +52,17 @@ class JsonProtocolSpec extends FlatSpec with Matchers {
     val outputAnnos = JsonProtocol.deserialize(annosString)
     inputAnnos should be (outputAnnos)
   }
+
+  "Annotation serialization during logging" should "not throw an exception" in {
+    val compiler = new firrtl.stage.transforms.Compiler(Seq(Dependency[AnnoInjector]))
+    val circuit = Parser.parse("""
+      |circuit test :
+      |  module test :
+      |    output out : UInt<1>
+      |    out <= UInt(0)
+      """.stripMargin)
+    Logger.makeScope(LogLevelAnnotation(LogLevel.Trace) :: Nil) {
+      compiler.execute(CircuitState(circuit, Nil))
+    }
+  }
 }