Implement "Field Selection Merging" validation

benchmarks/src/main/scala/caliban/GraphQLBenchmarks.scala

@@ -125,6 +125,103 @@ class GraphQLBenchmarks {
               }
                 """
 
+  val fragmentsQuery = s"""
+              query IntrospectionQuery {
+                __schema {
+                  queryType {
+                    name
+                    ${"...on __Type { name }" * 100}
+                  }
+                  mutationType { name }
+                  subscriptionType { name }
+                  types {
+                    ...FullType
+                  }
+                  directives {
+                    name
+                    description
+                    locations
+                    args {
+                      ...InputValue
+                    }
+                  }
+                }
+              }
+
+              fragment FullType on __Type {
+                kind
+                name
+                description
+                fields(includeDeprecated: true) {
+                  name
+                  description
+                  args {
+                    ...InputValue
+                  }
+                  type {
+                    ...TypeRef
+                  }
+                  isDeprecated
+                  deprecationReason
+                }
+                inputFields {
+                  ...InputValue
+                }
+                interfaces {
+                  ...TypeRef
+                }
+                enumValues(includeDeprecated: true) {
+                  name
+                  description
+                  isDeprecated
+                  deprecationReason
+                }
+                possibleTypes {
+                  ...TypeRef
+                }
+              }
+
+              fragment InputValue on __InputValue {
+                name
+                description
+                type { ...TypeRef }
+                defaultValue
+              }
+
+              fragment TypeRef on __Type {
+                kind
+                name
+                ofType {
+                  kind
+                  name
+                  ofType {
+                    kind
+                    name
+                    ofType {
+                      kind
+                      name
+                      ofType {
+                        kind
+                        name
+                        ofType {
+                          kind
+                          name
+                          ofType {
+                            kind
+                            name
+                            ofType {
+                              kind
+                              name
+                            }
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+                """
+
   val runtime: Runtime[ZEnv] = new BootstrapRuntime {
     override val platform: Platform = Platform.benchmark
   }
@@ -160,12 +257,19 @@ class GraphQLBenchmarks {
     ()
   }
 
-  implicit val OriginEnum: EnumType[Origin]             = deriveEnumType[Origin]()
-  implicit val CaptainType: ObjectType[Unit, Captain]   = deriveObjectType[Unit, Captain]()
-  implicit val PilotType: ObjectType[Unit, Pilot]       = deriveObjectType[Unit, Pilot]()
-  implicit val EngineerType: ObjectType[Unit, Engineer] = deriveObjectType[Unit, Engineer]()
-  implicit val MechanicType: ObjectType[Unit, Mechanic] = deriveObjectType[Unit, Mechanic]()
-  implicit val RoleType: UnionType[Unit] = UnionType(
+  @Benchmark
+  def fragmentsCaliban(): Unit = {
+    val io = interpreter.execute(fragmentsQuery)
+    runtime.unsafeRun(io)
+    ()
+  }
+
+  implicit val OriginEnum: EnumType[Origin]               = deriveEnumType[Origin]()
+  implicit val CaptainType: ObjectType[Unit, Captain]     = deriveObjectType[Unit, Captain]()
+  implicit val PilotType: ObjectType[Unit, Pilot]         = deriveObjectType[Unit, Pilot]()
+  implicit val EngineerType: ObjectType[Unit, Engineer]   = deriveObjectType[Unit, Engineer]()
+  implicit val MechanicType: ObjectType[Unit, Mechanic]   = deriveObjectType[Unit, Mechanic]()
+  implicit val RoleType: UnionType[Unit]                  = UnionType(
     "Role",
     types = List(PilotType, EngineerType, MechanicType, CaptainType)
   )
@@ -236,4 +340,12 @@ class GraphQLBenchmarks {
     ()
   }
 
+  @Benchmark
+  def fragmentsSangria(): Unit = {
+    val future: Future[Json] =
+      Future.fromTry(QueryParser.parse(fragmentsQuery)).flatMap(queryAst => Executor.execute(schema, queryAst))
+    Await.result(future, 1 minute)
+    ()
+  }
+
 }

core/src/main/scala/caliban/validation/FieldMap.scala

@@ -0,0 +1,58 @@
+package caliban.validation
+
+import caliban.introspection.adt._
+import caliban.parsing.adt.Selection.{ Field, FragmentSpread, InlineFragment }
+import caliban.parsing.adt._
+import Utils._
+
+object FieldMap {
+  val empty: FieldMap = Map.empty
+
+  implicit class FieldMapOps(val self: FieldMap) extends AnyVal {
+    def |+|(that: FieldMap): FieldMap =
+      (self.keySet ++ that.keySet).map { k =>
+        k -> (self.get(k).getOrElse(Set.empty) ++ that.get(k).getOrElse(Set.empty))
+      }.toMap
+
+    def show =
+      self.map { case (k, fields) =>
+        s"$k -> ${fields.map(_.fieldDef.name).mkString(", ")}"
+      }.mkString("\n")
+
+    def addField(
+      f: Field,
+      parentType: __Type,
+      selection: Field
+    ): FieldMap = {
+      val responseName = f.alias.getOrElse(f.name)
+
+      getFields(parentType)
+        .flatMap(fields => fields.find(_.name == f.name))
+        .map { f =>
+          val sf    = SelectedField(parentType, selection, f)
+          val entry = self.get(responseName).map(_ + sf).getOrElse(Set(sf))
+          self + (responseName -> entry)
+        }
+        .getOrElse(self)
+    }
+  }
+
+  def apply(context: Context, parentType: __Type, selectionSet: Iterable[Selection]): FieldMap =
+    selectionSet.foldLeft(FieldMap.empty)({ case (fields, selection) =>
+      selection match {
+        case FragmentSpread(name, directives)               =>
+          context.fragments
+            .get(name)
+            .map { definition =>
+              val typ = getType(Some(definition.typeCondition), parentType, context)
+              apply(context, typ, definition.selectionSet) |+| fields
+            }
+            .getOrElse(fields)
+        case f: Field                                       =>
+          fields.addField(f, parentType, f)
+        case InlineFragment(typeCondition, _, selectionSet) =>
+          val typ = getType(typeCondition, parentType, context)
+          apply(context, typ, selectionSet) |+| fields
+      }
+    })
+}

core/src/main/scala/caliban/validation/FragmentValidator.scala

@@ -0,0 +1,133 @@
+package caliban.validation
+
+import caliban.CalibanError.ValidationError
+import caliban.introspection.adt._
+import caliban.parsing.adt.Selection
+import zio.{ Chunk, IO, UIO }
+import Utils._
+import Utils.syntax._
+import scala.collection.mutable
+
+object FragmentValidator {
+  def findConflictsWithinSelectionSet(
+    context: Context,
+    parentType: __Type,
+    selectionSet: List[Selection]
+  ): IO[ValidationError, Unit] = {
+    val shapeCache   = scala.collection.mutable.Map.empty[Iterable[Selection], Chunk[String]]
+    val parentsCache = scala.collection.mutable.Map.empty[Iterable[Selection], Chunk[String]]
+    val groupsCache  = scala.collection.mutable.Map.empty[Set[SelectedField], Chunk[Set[SelectedField]]]
+
+    def sameResponseShapeByName(context: Context, parentType: __Type, set: Iterable[Selection]): Chunk[String] =
+      shapeCache.get(set) match {
+        case Some(value) => value
+        case None        =>
+          val fields = FieldMap(context, parentType, set)
+          val res    = Chunk.fromIterable(fields.flatMap { case (name, values) =>
+            cross(values).flatMap { case (f1, f2) =>
+              if (doTypesConflict(f1.fieldDef.`type`(), f2.fieldDef.`type`())) {
+                Chunk(
+                  s"$name has conflicting types: ${f1.parentType.name.getOrElse("")}.${f1.fieldDef.name} and ${f2.parentType.name
+                    .getOrElse("")}.${f2.fieldDef.name}. Try using an alias."
+                )
+              } else
+                sameResponseShapeByName(context, parentType, f1.selection.selectionSet ++ f2.selection.selectionSet)
+            }
+          })
+          shapeCache.put(set, res)
+          res
+      }
+
+    def sameForCommonParentsByName(context: Context, parentType: __Type, set: Iterable[Selection]): Chunk[String] =
+      parentsCache.get(set) match {
+        case Some(value) => value
+        case None        =>
+          val fields = FieldMap(context, parentType, set)
+          val res    = Chunk.fromIterable(fields.flatMap({ case (name, fields) =>
+            groupByCommonParents(context, parentType, fields).flatMap { group =>
+              val merged = group.flatMap(_.selection.selectionSet)
+              requireSameNameAndArguments(group) ++ sameForCommonParentsByName(context, parentType, merged)
+            }
+          }))
+          parentsCache.put(set, res)
+          res
+      }
+
+    def doTypesConflict(t1: __Type, t2: __Type): Boolean =
+      if (isNonNull(t1))
+        if (isNonNull(t2)) (t1.ofType, t2.ofType).mapN((p1, p2) => doTypesConflict(p1, p2)).getOrElse(true)
+        else true
+      else if (isNonNull(t2))
+        true
+      else if (isListType(t1))
+        if (isListType(t2)) (t1.ofType, t2.ofType).mapN((p1, p2) => doTypesConflict(p1, p2)).getOrElse(true)
+        else true
+      else if (isListType(t2))
+        true
+      else if (isLeafType(t1) && isLeafType(t2)) {
+        t1.name != t2.name
+      } else if (!isComposite(t1) || !isComposite(t2))
+        true
+      else
+        false
+
+    def requireSameNameAndArguments(fields: Set[SelectedField]) =
+      cross(fields).flatMap { case (f1, f2) =>
+        if (f1.fieldDef.name != f2.fieldDef.name) {
+          List(
+            s"${f1.parentType.name.getOrElse("")}.${f1.fieldDef.name} and ${f2.parentType.name.getOrElse("")}.${f2.fieldDef.name} are different fields."
+          )
+        } else if (f1.selection.arguments != f2.selection.arguments)
+          List(s"${f1.fieldDef.name} and ${f2.fieldDef.name} have different arguments")
+        else List()
+      }
+
+    def groupByCommonParents(
+      context: Context,
+      parentType: __Type,
+      fields: Set[SelectedField]
+    ): Chunk[Set[SelectedField]] =
+      groupsCache.get(fields) match {
+        case Some(value) => value
+        case None        =>
+          val abstractGroup = fields.collect {
+            case field if !isConcrete(field.parentType) => field
+          }
+
+          val concreteGroups = fields
+            .collect({
+              case f @ SelectedField(
+                    __Type(_, Some(name), _, _, _, _, _, _, _, _, _),
+                    _,
+                    _
+                  ) if isConcrete(f.parentType) =>
+                (name, f)
+            })
+            .foldLeft(mutable.Map.empty[String, Set[SelectedField]]) { case (acc, (name, field)) =>
+              val value = acc.get(name).map(_ + field).getOrElse(Set(field))
+              acc.put(name, value)
+              acc
+            }
+
+          val res =
+            if (concreteGroups.size < 1) Chunk(fields)
+            else Chunk.fromIterable(concreteGroups.values.map(_ ++ abstractGroup))
+
+          groupsCache.put(fields, res)
+          res
+      }
+
+    val fields = FieldMap(
+      context,
+      parentType,
+      selectionSet
+    )
+
+    val conflicts = sameResponseShapeByName(context, parentType, selectionSet) ++
+      sameForCommonParentsByName(context, parentType, selectionSet)
+
+    IO.whenCase(conflicts) { case Chunk(head, _*) =>
+      IO.fail(ValidationError(head, ""))
+    }
+  }
+}