feat(compiler): Handle error function exit in tracing mode [LNG-250] (#921)

* Wrap function calls with xor

* Do not detach tracing call in case of error exit

* Fix comment

model/src/main/scala/aqua/model/ValueModel.scala

@@ -25,11 +25,16 @@ object ValueModel {
   def errorCode(error: VarModel): Option[VarModel] =
     error.intoField("error_code")
 
+  def errorMessage(error: VarModel): Option[VarModel] =
+    error.intoField("message")
+
   val error = VarModel.fromVarRaw(ValueRaw.error)
   val errorType = ValueRaw.errorType
 
   // NOTE: It should be safe as `:error:` should have `error_code` field
   val lastErrorCode = errorCode(error).get
+  // NOTE: It should be safe as `:error:` should have `message` field
+  val lastErrorMessage = errorMessage(error).get
 
   implicit object ValueModelEq extends Eq[ValueModel] {
     override def eqv(x: ValueModel, y: ValueModel): Boolean = x == y

model/transform/src/main/scala/aqua/model/transform/funcop/Tracing.scala

@@ -1,23 +1,15 @@
 package aqua.model.transform.funcop
 
-import cats.data.Chain
-
-import cats.Eval
-
-import aqua.model.{
-  CallModel,
-  CallServiceModel,
-  LiteralModel,
-  MetaModel,
-  OpModel,
-  SeqModel,
-  ValueModel
-}
+import aqua.model.*
 import aqua.model.transform.pre.InitPeerCallable
 import aqua.model.ParModel
 import aqua.model.DetachModel
 import aqua.model.transform.TransformConfig.TracingConfig
 
+import cats.data.Chain
+import cats.Eval
+import aqua.types.ScalarType
+
 final case class Tracing(
   enabledConfig: Option[TracingConfig],
   initCallable: InitPeerCallable
@@ -41,18 +33,39 @@ final case class Tracing(
           .fold(child)(traceCall =>
             /* seq:
                  detach: call tracing enter
-                 <call-arrow-code>
-                 detach: call tracing exit */
+                 xor:
+                   seq:
+                     <call-arrow-code>
+                     detach: call tracing exit
+                   seq:
+                     call tracing error exit
+                     rethrow error
+             */
             SeqModel.wrap(
               DetachModel.wrap(
                 initCallable.onInitPeer.wrap(
                   traceCall(Event.Enter)
                 )
               ),
-              child,
-              DetachModel.wrap(
-                initCallable.onInitPeer.wrap(
-                  traceCall(Event.Exit)
+              XorModel.wrap(
+                SeqModel.wrap(
+                  child,
+                  DetachModel.wrap(
+                    initCallable.onInitPeer.wrap(
+                      traceCall(Event.Exit)
+                    )
+                  )
+                ),
+                SeqModel.wrap(
+                  /**
+                   * NOTE: Here we don't wrap trace call
+                   * with detach because Aqua VM ignores
+                   * it if it is detached.
+                   */
+                  initCallable.onInitPeer.wrap(
+                    traceCall(Event.ErrorExit)
+                  ),
+                  FailModel(ValueModel.error).leaf
                 )
               )
             )
@@ -64,23 +77,47 @@ final case class Tracing(
 object Tracing {
 
   enum Event {
-    case Enter, Exit
+    case Enter, Exit, ErrorExit
 
-    def toArg: ValueModel = LiteralModel.quote(this match {
+    def toArg(suffix: String = ""): ValueModel = LiteralModel.quote((this match {
       case Enter => "enter"
       case Exit => "exit"
-    })
+      case ErrorExit => "exit with error"
+    }) + suffix)
   }
 
-  def traceCallModel(config: TracingConfig, arrowName: String)(
+  private def traceCallModel(config: TracingConfig, arrowName: String)(
     event: Event
-  ): OpModel.Tree =
-    CallServiceModel(
-      LiteralModel.quote(config.serviceId),
-      config.serviceFuncName,
-      CallModel(
-        args = List(LiteralModel.quote(arrowName), event.toArg),
-        exportTo = Nil
-      )
-    ).leaf
+  ): OpModel.Tree = {
+    val serviceCall = (msg: ValueModel) =>
+      CallServiceModel(
+        LiteralModel.quote(config.serviceId),
+        config.serviceFuncName,
+        CallModel(
+          args = List(LiteralModel.quote(arrowName), msg),
+          exportTo = Nil
+        )
+      ).leaf
+
+    event match {
+      case Event.ErrorExit =>
+        val errorName = "-return-error-msg-"
+
+        RestrictionModel(
+          errorName,
+          ScalarType.string
+        ).wrap(
+          CallServiceModel(
+            LiteralModel.quote("op"),
+            "concat_strings",
+            CallModel(
+              args = List(event.toArg(": "), ValueModel.lastErrorMessage),
+              exportTo = List(CallModel.Export(errorName, ScalarType.string))
+            )
+          ).leaf,
+          serviceCall(VarModel(errorName, ScalarType.string))
+        )
+      case _ => serviceCall(event.toArg())
+    }
+  }
 }