From 23febad4c14872549e118158f701696f8067507d Mon Sep 17 00:00:00 2001
From: Andriy Plokhotnyuk <plokhotnyuk@gmail.com>
Date: Mon, 30 Dec 2024 16:05:30 +0100
Subject: [PATCH] Fix the stack overflow on creation of JSON codecs for
 recursive data structures (#760)

* Fix stack overflow on creation of JSON codecs for recursive data structures

* Fix formatting
---
 .../main/scala/zio/schema/codec/JsonCodec.scala   |  6 ++----
 .../scala/zio/schema/codec/JsonCodecSpec.scala    | 15 ++++++++++++++-
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala b/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
index b4df65f68..58c0b1525 100644
--- a/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
+++ b/zio-schema-json/shared/src/main/scala/zio/schema/codec/JsonCodec.scala
@@ -341,7 +341,7 @@ object JsonCodec {
         case Schema.GenericRecord(_, structure, _)                      => recordEncoder(structure.toChunk, cfg)
         case Schema.Either(left, right, _)                              => ZJsonEncoder.either(schemaEncoder(left, cfg, discriminatorTuple), schemaEncoder(right, cfg, discriminatorTuple))
         case Schema.Fallback(left, right, _, _)                         => fallbackEncoder(schemaEncoder(left, cfg, discriminatorTuple), schemaEncoder(right, cfg, discriminatorTuple))
-        case l @ Schema.Lazy(_)                                         => schemaEncoder(l.schema, cfg, discriminatorTuple)
+        case l @ Schema.Lazy(_)                                         => ZJsonEncoder.suspend(schemaEncoder(l.schema, cfg, discriminatorTuple))
         case s: Schema.Record[A]                                        => caseClassEncoder(s, cfg, discriminatorTuple)
         case e @ Schema.Enum1(_, c, _)                                  => enumEncoder(e, cfg, c)
         case e @ Schema.Enum2(_, c1, c2, _)                             => enumEncoder(e, cfg, c1, c2)
@@ -725,7 +725,7 @@ object JsonCodec {
       case Schema.GenericRecord(_, structure, _)          => recordDecoder(structure.toChunk, schema.annotations.contains(rejectExtraFields()))
       case Schema.Either(left, right, _)                  => ZJsonDecoder.either(schemaDecoder(left, -1), schemaDecoder(right, -1))
       case s @ Schema.Fallback(_, _, _, _)                => fallbackDecoder(s)
-      case l @ Schema.Lazy(_)                             => schemaDecoder(l.schema, discriminator)
+      case l @ Schema.Lazy(_)                             => ZJsonDecoder.suspend(schemaDecoder(l.schema, discriminator))
       //case Schema.Meta(_, _)                                                                           => astDecoder
       case s @ Schema.CaseClass0(_, _, _)                                => caseClass0Decoder(discriminator, s)
       case s @ Schema.CaseClass1(_, _, _, _)                             => caseClass1Decoder(discriminator, s)
@@ -1094,10 +1094,8 @@ object JsonCodec {
                 JsonError.Message("Fallback decoder was unable to decode both left and right sides") :: trace
               )
           }
-
         }
       }
-
   }
 
   //scalafmt: { maxColumn = 400, optIn.configStyleArguments = false }
diff --git a/zio-schema-json/shared/src/test/scala/zio/schema/codec/JsonCodecSpec.scala b/zio-schema-json/shared/src/test/scala/zio/schema/codec/JsonCodecSpec.scala
index b6dd57558..568f75c89 100644
--- a/zio-schema-json/shared/src/test/scala/zio/schema/codec/JsonCodecSpec.scala
+++ b/zio-schema-json/shared/src/test/scala/zio/schema/codec/JsonCodecSpec.scala
@@ -1461,7 +1461,14 @@ object JsonCodecSpec extends ZIOSpecDefault {
       },
       test("all optional fields empty") {
         assertEncodesThenDecodes(AllOptionalFields.schema, AllOptionalFields(None, None, None))
-      }
+      },
+      test("recursive data structure")(
+        assertDecodes(
+          Schema[Recursive],
+          Recursive(Some(Recursive(None))),
+          charSequenceToByteChunk("""{"n":{"n":null}}""")
+        )
+      )
     ),
     suite("record")(
       test("any") {
@@ -2368,4 +2375,10 @@ object JsonCodecSpec extends ZIOSpecDefault {
 
     case class Case23(value: String) extends Enum23Cases
   }
+
+  case class Recursive(n: Option[Recursive] = None)
+
+  object Recursive {
+    implicit val schema: Schema[Recursive] = DeriveSchema.gen
+  }
 }