Recursive type in endpoint input causes misleading error

[kubukoz]

Tested on 0.12.11.

For this spec:

namespace demo.smithy

use smithy4s.api#simpleRestJson

@simpleRestJson
service DemoService {
  version: "0.0.1",
  operations: [CreateHello],
}

@http(method: "PUT", uri: "/subscriptions")
@idempotent
operation CreateHello {
  input: HelloInput,
  output: HelloOutput,
}

structure HelloInput {
  @httpPayload
  @required
  hello: Hello
}

structure HelloOutput {

}

structure Hello {
  @required
  id: String,
  // recursive call
  next: Hello
}

For this Scala:

import smithy4s.http4s.SimpleRestJsonBuilder
import demo.smithy.DemoService
import org.http4s.client.Client
import org.http4s.HttpApp
import cats.effect.IO
import org.http4s.Uri

object Main extends App {

  SimpleRestJsonBuilder(DemoService).client(
    HttpApp.notFound[IO],
    Uri.unsafeFromString("http://localhost")
  )
}

Run sbt run.

If you remove the recursive call in the Hello shape, it works. If you keep it:

[info] running Main 
[error] java.lang.RuntimeException: Operation CreateHello is not bound to http semantics
[error]         at scala.sys.package$.error(package.scala:30)
[error]         at smithy4s.http4s.SmithyHttp4sReverseRouter$$anon$1.$anonfun$apply$1(SmithyHttp4sReverseRouter.scala:57)
[error]         at scala.Option.getOrElse(Option.scala:189)
[error]         at smithy4s.http4s.SmithyHttp4sReverseRouter$$anon$1.apply(SmithyHttp4sReverseRouter.scala:56)
[error]         at smithy4s.http4s.SmithyHttp4sReverseRouter$$anon$1.apply(SmithyHttp4sReverseRouter.scala:43)
[error]         at smithy4s.Transformation$$anon$3.$anonfun$map$1(Transformation.scala:61)
[error]         at scala.collection.immutable.List.foreach(List.scala:431)
[error]         at smithy4s.Transformation$$anon$3.<init>(Transformation.scala:59)
[error]         at smithy4s.Transformation.precompute(Transformation.scala:56)
[error]         at smithy4s.Transformation.precompute$(Transformation.scala:53)
[error]         at smithy4s.http4s.SmithyHttp4sReverseRouter$$anon$1.precompute(SmithyHttp4sReverseRouter.scala:43)
[error]         at smithy4s.http4s.SmithyHttp4sReverseRouter.<init>(SmithyHttp4sReverseRouter.scala:60)
[error]         at smithy4s.http4s.SimpleProtocolBuilder$ServiceBuilder.client(SimpleProtocolBuilder.scala:82)
[error]         at Main$.delayedEndpoint$Main$1(Main.scala:10)
[error]         at Main$delayedInit$body.apply(Main.scala:8)
[error]         at scala.Function0.apply$mcV$sp(Function0.scala:39)
[error]         at scala.Function0.apply$mcV$sp$(Function0.scala:39)
[error]         at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
[error]         at scala.App.$anonfun$main$1$adapted(App.scala:80)
[error]         at scala.collection.immutable.List.foreach(List.scala:431)
[error]         at scala.App.main(App.scala:80)
[error]         at scala.App.main$(App.scala:78)
[error]         at Main$.main(Main.scala:8)
[error]         at Main.main(Main.scala)
[error]         at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error]         at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error]         at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error]         at java.base/java.lang.reflect.Method.invoke(Method.java:566)
[error] stack trace is suppressed; run last Compile / run for the full output
[error] (Compile / run) Operation CreateHello is not bound to http semantics
[error] Total time: 1 s, completed Apr 13, 2022, 7:28:31 PM

[kubukoz]

Generated before recursion:

//Hello.scala
package demo.smithy

import smithy4s.syntax._

case class Hello(id: String)
object Hello extends smithy4s.ShapeTag.Companion[Hello] {
  val id: smithy4s.ShapeId = smithy4s.ShapeId("demo.smithy", "Hello")

  val hints : smithy4s.Hints = smithy4s.Hints(
    id,
  )

  val schema: smithy4s.Schema[Hello] = struct(
    string.required[Hello]("id", _.id).withHints(smithy.api.Required()),
  ){
    Hello.apply
  }.withHints(hints)
  implicit val staticSchema : schematic.Static[smithy4s.Schema[Hello]] = schematic.Static(schema)
}

//HelloInput.scala
package demo.smithy

import smithy4s.syntax._

case class HelloInput(hello: Hello)
object HelloInput extends smithy4s.ShapeTag.Companion[HelloInput] {
  val id: smithy4s.ShapeId = smithy4s.ShapeId("demo.smithy", "HelloInput")

  val hints : smithy4s.Hints = smithy4s.Hints(
    id,
  )

  val schema: smithy4s.Schema[HelloInput] = struct(
    Hello.schema.required[HelloInput]("hello", _.hello).withHints(smithy.api.Required(), smithy.api.HttpPayload()),
  ){
    HelloInput.apply
  }.withHints(hints)
  implicit val staticSchema : schematic.Static[smithy4s.Schema[HelloInput]] = schematic.Static(schema)
}

After recursion:

//Hello.scala
package demo.smithy

import smithy4s.syntax._

case class Hello(id: String, next: Option[Hello] = None)
object Hello extends smithy4s.ShapeTag.Companion[Hello] {
  val id: smithy4s.ShapeId = smithy4s.ShapeId("demo.smithy", "Hello")

  val hints : smithy4s.Hints = smithy4s.Hints(
    id,
  )

  val schema: smithy4s.Schema[Hello] = recursive(struct(
    string.required[Hello]("id", _.id).withHints(smithy.api.Required()),
    Hello.schema.optional[Hello]("next", _.next),
  ){
    Hello.apply
  }.withHints(hints))
  implicit val staticSchema : schematic.Static[smithy4s.Schema[Hello]] = schematic.Static(schema)
}

//HelloInput.scala
package demo.smithy

import smithy4s.syntax._

case class HelloInput(hello: Hello)
object HelloInput extends smithy4s.ShapeTag.Companion[HelloInput] {
  val id: smithy4s.ShapeId = smithy4s.ShapeId("demo.smithy", "HelloInput")

  val hints : smithy4s.Hints = smithy4s.Hints(
    id,
  )

  val schema: smithy4s.Schema[HelloInput] = recursive(struct(
    Hello.schema.required[HelloInput]("hello", _.hello).withHints(smithy.api.Required(), smithy.api.HttpPayload()),
  ){
    HelloInput.apply
  }.withHints(hints))
  implicit val staticSchema : schematic.Static[smithy4s.Schema[HelloInput]] = schematic.Static(schema)
}

First thing that surprises me is that HelloInput has a recursive(...) there, even though it doesn't actually have recursion on its own.