Generate NoStackTrace error types

modules/bootstrapped/src/generated/smithy4s/example/EHFallbackClientError.scala

@@ -1,13 +1,14 @@
 package smithy4s.example
 
+import scala.util.control.NoStackTrace
 import smithy4s.Hints
 import smithy4s.Schema
 import smithy4s.ShapeId
 import smithy4s.ShapeTag
 import smithy4s.schema.Schema.string
 import smithy4s.schema.Schema.struct
 
-final case class EHFallbackClientError(message: Option[String] = None) extends Throwable {
+final case class EHFallbackClientError(message: Option[String] = None) extends NoStackTrace {
   override def getMessage(): String = message.orNull
 }
 object EHFallbackClientError extends ShapeTag.Companion[EHFallbackClientError] {

modules/bootstrapped/src/generated/smithy4s/example/EHNotFound.scala

@@ -1,13 +1,14 @@
 package smithy4s.example
 
+import scala.util.control.NoStackTrace
 import smithy4s.Hints
 import smithy4s.Schema
 import smithy4s.ShapeId
 import smithy4s.ShapeTag
 import smithy4s.schema.Schema.string
 import smithy4s.schema.Schema.struct
 
-final case class EHNotFound(message: Option[String] = None) extends Throwable {
+final case class EHNotFound(message: Option[String] = None) extends NoStackTrace {
   override def getMessage(): String = message.orNull
 }
 object EHNotFound extends ShapeTag.Companion[EHNotFound] {

modules/bootstrapped/src/generated/smithy4s/example/EHServiceUnavailable.scala

@@ -1,13 +1,14 @@
 package smithy4s.example
 
+import scala.util.control.NoStackTrace
 import smithy4s.Hints
 import smithy4s.Schema
 import smithy4s.ShapeId
 import smithy4s.ShapeTag
 import smithy4s.schema.Schema.string
 import smithy4s.schema.Schema.struct
 
-final case class EHServiceUnavailable(message: Option[String] = None) extends Throwable {
+final case class EHServiceUnavailable(message: Option[String] = None) extends NoStackTrace {
   override def getMessage(): String = message.orNull
 }
 object EHServiceUnavailable extends ShapeTag.Companion[EHServiceUnavailable] {

modules/codegen/src/smithy4s/codegen/internals/CollisionAvoidance.scala

@@ -328,6 +328,8 @@ private[internals] object CollisionAvoidance {
     val option = NameRef("scala", "Option")
     val none = NameRef("scala", "None")
     val some = NameRef("scala", "Some")
+    val noStackTrace = NameRef("scala.util.control", "NoStackTrace")
+    val throwable = NameRef("java.lang", "Throwable")
 
   }
 

modules/codegen/src/smithy4s/codegen/internals/IR.scala

@@ -277,6 +277,7 @@ private[internals] sealed trait Hint
 private[internals] object Hint {
   case object Trait extends Hint
   case object Error extends Hint
+  case object NoStackTrace extends Hint
   case object PackedInputs extends Hint
   case object NoDefault extends Hint
   case object ErrorMessage extends Hint

modules/codegen/src/smithy4s/codegen/internals/LineSegment.scala

@@ -58,7 +58,7 @@ private[codegen] object LineSegment {
 
     def isAutoImported: Boolean = {
       val value = pkg.mkString(".")
-      value.startsWith("scala") || value.equalsIgnoreCase("java.lang")
+      NameRef.autoImportedNames.exists(_.equalsIgnoreCase(value))
     }
     def getNamePrefix: String = name.split("\\.").head
     def +(piece: String): NameRef = {
@@ -79,6 +79,12 @@ private[codegen] object LineSegment {
   }
 
   object NameRef {
+    val autoImportedNames: List[String] = List(
+      "scala",
+      "java.lang",
+      "scala.Predef",
+      "scala.collection.immutable"
+    )
     implicit val nameRefShow: Show[NameRef] = Show.show[NameRef](_.asImport)
     def apply(pkg: String, name: String): NameRef =
       NameRef(pkg.split("\\.").toList, name, List.empty)

modules/codegen/src/smithy4s/codegen/internals/Renderer.scala

@@ -628,11 +628,15 @@ private[internals] class Renderer(compilationUnit: CompilationUnit) { self =>
 
     lines(
       if (hints.contains(Hint.Error)) {
+        val exception =
+          if (hints.contains(Hint.NoStackTrace))
+            noStackTrace
+          else throwable
         val mixinExtensions = if (mixins.nonEmpty) {
           val ext = mixins.map(m => line"$m").intercalate(line" with ")
           line" with $ext"
         } else Line.empty
-        block(line"$decl extends Throwable$mixinExtensions") {
+        block(line"$decl extends $exception$mixinExtensions") {
           fields
             .find { f =>
               f.hints.contains_(Hint.ErrorMessage) ||

modules/codegen/src/smithy4s/codegen/internals/SmithyToIR.scala

@@ -21,6 +21,7 @@ import cats.implicits._
 import smithy4s.meta.AdtMemberTrait
 import smithy4s.meta.ErrorMessageTrait
 import smithy4s.meta.IndexedSeqTrait
+import smithy4s.meta.NoStackTraceTrait
 import smithy4s.meta.PackedInputsTrait
 import smithy4s.meta.RefinementTrait
 import smithy4s.meta.VectorTrait
@@ -913,6 +914,8 @@ private[codegen] class SmithyToIR(model: Model, namespace: String) {
       Hint.Deprecated(d.getMessage.asScala, d.getSince.asScala)
     case _: ErrorMessageTrait =>
       Hint.ErrorMessage
+    case _: NoStackTraceTrait =>
+      Hint.NoStackTrace
     case _: VectorTrait =>
       Hint.SpecializedList.Vector
     case _: IndexedSeqTrait =>

modules/protocol/resources/META-INF/services/software.amazon.smithy.model.traits.TraitService

@@ -3,6 +3,7 @@ smithy4s.meta.AdtMemberTrait$Provider
 smithy4s.meta.VectorTrait$Provider
 smithy4s.meta.IndexedSeqTrait$Provider
 smithy4s.meta.ErrorMessageTrait$Provider
+smithy4s.meta.NoStackTraceTrait$Provider
 smithy4s.meta.RefinementTrait$Provider
 smithy4s.meta.UnwrapTrait$Provider
 smithy4s.meta.AdtTrait$Provider

modules/protocol/resources/META-INF/smithy/smithy4s.meta.smithy

@@ -149,3 +149,8 @@ structure typeclass {
 /// include a Service Product version of the service.
 @trait(selector: ":is(service)")
 structure generateServiceProduct {}
+
+/// Placing this trait on an error will cause the generated code to exclude the stacktrace
+///  via extending scala.util.control.NoStackTrace instead of Throwable.
+@trait(selector: "structure :is([trait|error])")
+structure noStackTrace {}

modules/protocol/src/smithy4s/meta/NoStackTraceTrait.java

@@ -0,0 +1,48 @@
+/*
+ *  Copyright 2021-2022 Disney Streaming
+ *
+ *  Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *     https://disneystreaming.github.io/TOST-1.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+package smithy4s.meta;
+
+import software.amazon.smithy.model.node.Node;
+import software.amazon.smithy.model.node.ObjectNode;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.traits.AnnotationTrait;
+import software.amazon.smithy.model.traits.AbstractTrait;
+
+public class NoStackTraceTrait extends AnnotationTrait {
+
+    public static ShapeId ID = ShapeId.from("smithy4s.meta#noStackTrace");
+
+    public NoStackTraceTrait(ObjectNode node) {
+        super(ID, node);
+    }
+
+    public NoStackTraceTrait() {
+        super(ID, Node.objectNode());
+    }
+
+    public static final class Provider extends AbstractTrait.Provider {
+        public Provider() {
+            super(ID);
+        }
+
+        @Override
+        public NoStackTraceTrait createTrait(ShapeId target, Node node) {
+            return new NoStackTraceTrait(node.expectObjectNode());
+        }
+    }
+}
+

sampleSpecs/errorHandling.smithy

@@ -2,6 +2,8 @@ $version: "2"
 
 namespace smithy4s.example
 
+use smithy4s.meta#noStackTrace
+
 // Where the errors are placed in this spec doesn't necessarily "make sense" but is
 // mixed up to test some specific scenarios such as falling back to service-level
 // errors when no operation-level ones are found.
@@ -22,17 +24,20 @@ operation ErrorHandlingOperation {
   errors: [EHNotFound, EHFallbackServerError]
 }
 
+@noStackTrace
 @httpError(404)
 @error("client")
 structure EHNotFound {
   message: String
 }
 
+@noStackTrace
 @error("client")
 structure EHFallbackClientError {
   message: String
 }
 
+@noStackTrace
 @httpError(503)
 @error("server")
 structure EHServiceUnavailable {