Prevent merging of fragment fields into selection tree if fragment fi…

…eld merging is disabled (#571)

Tests/ApolloCodegenInternalTestHelpers/IRBuilderTestWrapper.swift

@@ -24,7 +24,10 @@ public class IRBuilderTestWrapper {
     operation operationDefinition: CompilationResult.OperationDefinition,
     mergingStrategy: MergedSelections.MergingStrategy = .all
   ) async -> IRTestWrapper<IR.Operation> {
-    let operation = await irBuilder.build(operation: operationDefinition)
+    let operation = await irBuilder.build(
+      operation: operationDefinition,
+      mergingNamedFragmentFields: mergingStrategy.contains(.namedFragments)
+    )
     return IRTestWrapper(
       irObject: operation,
       computedSelectionSetCache: .init(
@@ -38,7 +41,10 @@ public class IRBuilderTestWrapper {
     fragment fragmentDefinition: CompilationResult.FragmentDefinition,
     mergingStrategy: MergedSelections.MergingStrategy = .all
   ) async -> IRTestWrapper<IR.NamedFragment> {
-    let fragment = await irBuilder.build(fragment: fragmentDefinition)
+    let fragment = await irBuilder.build(
+      fragment: fragmentDefinition,
+      mergingNamedFragmentFields: mergingStrategy.contains(.namedFragments)
+    )
     return IRTestWrapper(
       irObject: fragment,
       computedSelectionSetCache: .init(

apollo-ios-codegen/Sources/ApolloCodegenLib/ApolloCodegen.swift

@@ -295,10 +295,16 @@ public class ApolloCodegen {
     ir: IRBuilder,
     fileManager: ApolloFileManager
   ) async throws -> NonFatalErrors {
+    let mergeNamedFragmentFields = config.experimentalFeatures.fieldMerging.options
+      .contains(.namedFragments)
+
     return try await nonFatalErrorCollectingTaskGroup() { group in
       for fragment in fragments {
         group.addTask {
-          let irFragment = await ir.build(fragment: fragment)
+          let irFragment = await ir.build(
+            fragment: fragment,
+            mergingNamedFragmentFields: mergeNamedFragmentFields
+          )
 
           let errors = try await FragmentFileGenerator(irFragment: irFragment, config: self.config)
             .generate(forConfig: self.config, fileManager: fileManager)
@@ -310,7 +316,10 @@ public class ApolloCodegen {
         group.addTask {
           async let identifier = self.operationIdentifierFactory.identifier(for: operation)
 
-          let irOperation = await ir.build(operation: operation)
+          let irOperation = await ir.build(
+            operation: operation,
+            mergingNamedFragmentFields: mergeNamedFragmentFields
+          )
 
           let errors = try await OperationFileGenerator(
             irOperation: irOperation,

apollo-ios-codegen/Sources/IR/IR+RootFieldBuilder.swift

@@ -16,23 +16,34 @@ class RootFieldBuilder {
   static func buildRootEntityField(
     forRootField rootField: CompilationResult.Field,
     onRootEntity rootEntity: Entity,
-    inIR ir: IRBuilder
+    inIR ir: IRBuilder,
+    mergingNamedFragmentFields: Bool
   ) async -> Result {
-    return await RootFieldBuilder(ir: ir, rootEntity: rootEntity)
-      .build(rootField: rootField)
+    return await RootFieldBuilder(
+      ir: ir,
+      rootEntity: rootEntity,
+      mergeInNamedFragmentFields: mergingNamedFragmentFields
+    )
+    .build(rootField: rootField)
   }
 
   private let ir: IRBuilder
   private let rootEntity: Entity
   private let entityStorage: DefinitionEntityStorage
+  private let mergeInNamedFragmentFields: Bool
   private var referencedFragments: ReferencedFragments = []
   @IsEverTrue private var containsDeferredFragment: Bool
 
   private var schema: Schema { ir.schema }
 
-  private init(ir: IRBuilder, rootEntity: Entity) {
+  private init(
+    ir: IRBuilder,
+    rootEntity: Entity,
+    mergeInNamedFragmentFields: Bool
+  ) {
     self.ir = ir
     self.rootEntity = rootEntity
+    self.mergeInNamedFragmentFields = mergeInNamedFragmentFields
     self.entityStorage = DefinitionEntityStorage(rootEntity: rootEntity)
   }
 
@@ -398,7 +409,10 @@ class RootFieldBuilder {
     spreadIntoParentWithTypePath parentTypeInfo: SelectionSet.TypeInfo,
     deferCondition: CompilationResult.DeferCondition? = nil
   ) async -> NamedFragmentSpread {
-    let fragment = await ir.build(fragment: fragmentSpread.fragment)
+    let fragment = await ir.build(
+      fragment: fragmentSpread.fragment,
+      mergingNamedFragmentFields: self.mergeInNamedFragmentFields
+    )
     referencedFragments.append(fragment)
     referencedFragments.append(contentsOf: fragment.referencedFragments)
 
@@ -425,7 +439,7 @@ class RootFieldBuilder {
       inclusionConditions: AnyOf(scope.conditions)
     )
 
-    if fragmentSpread.typeInfo.deferCondition == nil {
+    if mergeInNamedFragmentFields && fragmentSpread.typeInfo.deferCondition == nil {
       mergeAllSelectionsIntoEntitySelectionTrees(from: fragmentSpread)
     }
 

apollo-ios-codegen/Sources/IR/IRBuilder.swift

@@ -23,7 +23,8 @@ public class IRBuilder {
   }
 
   public func build(
-    operation operationDefinition: CompilationResult.OperationDefinition
+    operation operationDefinition: CompilationResult.OperationDefinition,
+    mergingNamedFragmentFields: Bool = true
   ) async -> Operation {
     let rootField = CompilationResult.Field(
       name: operationDefinition.operationType.rawValue,
@@ -38,7 +39,8 @@ public class IRBuilder {
     let result = await RootFieldBuilder.buildRootEntityField(
       forRootField: rootField,
       onRootEntity: rootEntity,
-      inIR: self
+      inIR: self,
+      mergingNamedFragmentFields: mergingNamedFragmentFields
     )
 
     return Operation(
@@ -86,7 +88,8 @@ public class IRBuilder {
   }
 
   public func build(
-    fragment fragmentDefinition: CompilationResult.FragmentDefinition
+    fragment fragmentDefinition: CompilationResult.FragmentDefinition,
+    mergingNamedFragmentFields: Bool = true
   ) async -> NamedFragment {
     await builtFragmentStorage.getFragment(named: fragmentDefinition.name) {
       let rootField = CompilationResult.Field(
@@ -102,7 +105,8 @@ public class IRBuilder {
       let result = await RootFieldBuilder.buildRootEntityField(
         forRootField: rootField,
         onRootEntity: rootEntity,
-        inIR: self
+        inIR: self,
+        mergingNamedFragmentFields: mergingNamedFragmentFields
       )
 
       return NamedFragment(