Fix anno deserialization when class field is not first (#2501)

Update `findTypeHints` to allow for the "class" field in JSON objects to
appear anywhere in the object. This used to rely on the field being the
very first in the object, which is easily violated when reading JSON
data generated externally, since an object's order of fields is
unspecified and can be arbitrarily scrambled.

Fixes #2497.

1 files changed, 12 insertions, 0 deletions

diff --git a/src/test/scala/firrtl/JsonProtocolSpec.scala b/src/test/scala/firrtl/JsonProtocolSpec.scala
index 0da43204..3e07542b 100644
--- a/src/test/scala/firrtl/JsonProtocolSpec.scala
+++ b/src/test/scala/firrtl/JsonProtocolSpec.scala
@@ -31,6 +31,8 @@ object JsonProtocolTestClasses {
       with HasSerializationHints {
     def typeHints = Seq(param.getClass)
   }
+
+  case class SimpleAnnotation(alpha: String) extends NoTargetAnnotation
 }
 
 import JsonProtocolTestClasses._
@@ -68,4 +70,14 @@ class JsonProtocolSpec extends AnyFlatSpec {
     val deserAnno = serializeAndDeserialize(anno)
     assert(anno == deserAnno)
   }
+
+  "JSON object order" should "not affect deserialization" in {
+    val anno = SimpleAnnotation("hello")
+    val serializedAnno = """[{
+      "alpha": "hello",
+      "class": "firrtlTests.JsonProtocolTestClasses$SimpleAnnotation"
+    }]"""
+    val deserAnno = JsonProtocol.deserialize(serializedAnno).head
+    assert(anno == deserAnno)
+  }
 }