[Swift] FlatBuffers createMonster method doesn't treat struct properly (#5992)

* [Swift] FlatBuffers createMonster method doesn't treat struct properly

This PR fixed a issue where a struct is not treated properly when use
create inside.

A example would be the pos inside Monster. The createMonster method
takes an Offset for pos. However, FlatBuffersBuilder.add(struct:)
doesn't really take Offset argument. That means we don't really add a
struct at all for Monster.

It will show up as the pos never set.

This doesn't show up in FlatBuffersMonsterWriterTests.swift because it
implements its own createMonster method, which happens do the dance
properly (i.e. first call create(struct) and then immediately call
add:).

This PR modified the `add(pos:)` interface such that it takes the
UnsafeMutableRawPointer directly, calling `create(struct:)` under the hood.

I can add unit tests once the direction of this PR approved.

* Fix object api pack method codegen.

* Add unit tests that uses Monster.createMonster method to serialize.

* Updated sample_binary.swift

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/FlatBuffersMonsterWriterTests.swift

@@ -45,6 +45,27 @@ class FlatBuffersMonsterWriterTests: XCTestCase {
         readMonster(fb: newBuf)
     }
 
+    func testCreateMonsterUsingCreateMonsterMethodWithNilPos() {
+        var fbb = FlatBufferBuilder(initialSize: 1)
+        let name = fbb.create(string: "Frodo")
+        let monster = Monster.createMonster(&fbb, offsetOfName: name)
+        fbb.finish(offset: monster)
+        let newMonster = Monster.getRootAsMonster(bb: fbb.sizedBuffer)
+        XCTAssertNil(newMonster.pos)
+        XCTAssertEqual(newMonster.name, "Frodo")
+    }
+
+    func testCreateMonsterUsingCreateMonsterMethodWithPosX() {
+        var fbb = FlatBufferBuilder(initialSize: 1)
+        let pos = MyGame.Example.createVec3(x: 10, test2: .blue)
+        let name = fbb.create(string: "Barney")
+        let monster = Monster.createMonster(&fbb, structOfPos: pos, offsetOfName: name)
+        fbb.finish(offset: monster)
+        let newMonster = Monster.getRootAsMonster(bb: fbb.sizedBuffer)
+        XCTAssertEqual(newMonster.pos!.x, 10)
+        XCTAssertEqual(newMonster.name, "Barney")
+    }
+
     func testReadMonsterFromUnsafePointerWithoutCopying() {
         var array: [UInt8] = [48, 0, 0, 0, 77, 79, 78, 83, 0, 0, 0, 0, 36, 0, 72, 0, 40, 0, 0, 0, 38, 0, 32, 0, 0, 0, 28, 0, 0, 0, 27, 0, 20, 0, 16, 0, 12, 0, 4, 0, 0, 0, 0, 0, 0, 0, 11, 0, 36, 0, 0, 0, 164, 0, 0, 0, 0, 0, 0, 1, 60, 0, 0, 0, 68, 0, 0, 0, 76, 0, 0, 0, 0, 0, 0, 1, 88, 0, 0, 0, 120, 0, 0, 0, 0, 0, 80, 0, 0, 0, 128, 63, 0, 0, 0, 64, 0, 0, 64, 64, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 64, 2, 0, 5, 0, 6, 0, 0, 0, 2, 0, 0, 0, 64, 0, 0, 0, 48, 0, 0, 0, 2, 0, 0, 0, 30, 0, 40, 0, 10, 0, 20, 0, 152, 255, 255, 255, 4, 0, 0, 0, 4, 0, 0, 0, 70, 114, 101, 100, 0, 0, 0, 0, 5, 0, 0, 0, 0, 1, 2, 3, 4, 0, 0, 0, 5, 0, 0, 0, 116, 101, 115, 116, 50, 0, 0, 0, 5, 0, 0, 0, 116, 101, 115, 116, 49, 0, 0, 0, 9, 0, 0, 0, 77, 121, 77, 111, 110, 115, 116, 101, 114, 0, 0, 0, 3, 0, 0, 0, 20, 0, 0, 0, 36, 0, 0, 0, 4, 0, 0, 0, 240, 255, 255, 255, 32, 0, 0, 0, 248, 255, 255, 255, 36, 0, 0, 0, 12, 0, 8, 0, 0, 0, 0, 0, 0, 0, 4, 0, 12, 0, 0, 0, 28, 0, 0, 0, 5, 0, 0, 0, 87, 105, 108, 109, 97, 0, 0, 0, 6, 0, 0, 0, 66, 97, 114, 110, 101, 121, 0, 0, 5, 0, 0, 0, 70, 114, 111, 100, 111, 0, 0, 0]
         let unpacked = array.withUnsafeMutableBytes { (memory) -> MyGame.Example.MonsterT in
@@ -100,10 +121,10 @@ class FlatBuffersMonsterWriterTests: XCTestCase {
                                      type: Test.self)
         
         let stringTestVector = fbb.createVector(ofOffsets: [test1, test2])
-        
+
+        let posStruct = MyGame.Example.createVec3(x: 1, y: 2, z: 3, test1: 3, test2: .green, test3a: 5, test3b: 6)
         let mStart = Monster.startMonster(&fbb)
-        let posOffset = fbb.create(struct: MyGame.Example.createVec3(x: 1, y: 2, z: 3, test1: 3, test2: .green, test3a: 5, test3b: 6), type: Vec3.self)
-        Monster.add(pos: posOffset, &fbb)
+        Monster.add(pos: posStruct, &fbb)
         Monster.add(hp: 80, &fbb)
         Monster.add(name: str, &fbb)
         Monster.addVectorOf(inventory: inv, &fbb)

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/XCTestManifests.swift

@@ -20,6 +20,8 @@ extension FlatBuffersMonsterWriterTests {
         ("testCreateMonster", testCreateMonster),
         ("testCreateMonsterPrefixed", testCreateMonsterPrefixed),
         ("testCreateMonsterResizedBuffer", testCreateMonsterResizedBuffer),
+        ("testCreateMonsterUsingCreateMonsterMethodWithNilPos", testCreateMonsterUsingCreateMonsterMethodWithNilPos),
+        ("testCreateMonsterUsingCreateMonsterMethodWithPosX", testCreateMonsterUsingCreateMonsterMethodWithPosX),
         ("testData", testData),
         ("testReadFromOtherLanguages", testReadFromOtherLanguages),
         ("testReadMonsterFromUnsafePointerWithoutCopying", testReadMonsterFromUnsafePointerWithoutCopying),

tests/FlatBuffers.Test.Swift/Tests/FlatBuffers.Test.SwiftTests/monster_test_generated.swift

@@ -825,7 +825,7 @@ public struct Monster: FlatBufferObject {
     public var signedEnum: MyGame.Example.Race { let o = _accessor.offset(VTOFFSET.signedEnum.v); return o == 0 ? .none_ : MyGame.Example.Race(rawValue: _accessor.readBuffer(of: Int8.self, at: o)) ?? .none_ }
     @discardableResult public func mutate(signedEnum: MyGame.Example.Race) -> Bool {let o = _accessor.offset(VTOFFSET.signedEnum.v);  return _accessor.mutate(signedEnum.rawValue, index: o) }
     public static func startMonster(_ fbb: inout FlatBufferBuilder) -> UOffset { fbb.startTable(with: 49) }
-    public static func add(pos: Offset<UOffset>, _ fbb: inout FlatBufferBuilder) { fbb.add(structOffset: VTOFFSET.pos.p) }
+    public static func add(pos: UnsafeMutableRawPointer?, _ fbb: inout FlatBufferBuilder) { guard let pos = pos else { return }; fbb.create(struct: pos, type: MyGame.Example.Vec3.self); fbb.add(structOffset: VTOFFSET.pos.p) }
     public static func add(mana: Int16, _ fbb: inout FlatBufferBuilder) { fbb.add(element: mana, def: 150, at: VTOFFSET.mana.p) }
     public static func add(hp: Int16, _ fbb: inout FlatBufferBuilder) { fbb.add(element: hp, def: 100, at: VTOFFSET.hp.p) }
     public static func add(name: Offset<String>, _ fbb: inout FlatBufferBuilder) { fbb.add(offset: name, at: VTOFFSET.name.p)  }
@@ -875,7 +875,7 @@ public struct Monster: FlatBufferObject {
     public static func add(signedEnum: MyGame.Example.Race, _ fbb: inout FlatBufferBuilder) { fbb.add(element: signedEnum.rawValue, def: -1, at: VTOFFSET.signedEnum.p) }
     public static func endMonster(_ fbb: inout FlatBufferBuilder, start: UOffset) -> Offset<UOffset> { let end = Offset<UOffset>(offset: fbb.endTable(at: start)); fbb.require(table: end, fields: [10]); return end }
     public static func createMonster(_ fbb: inout FlatBufferBuilder,
-    offsetOfPos pos: Offset<UOffset> = Offset(),
+    structOfPos pos: UnsafeMutableRawPointer? = nil,
     mana: Int16 = 150,
     hp: Int16 = 100,
     offsetOfName name: Offset<String> = Offset(),
@@ -1010,6 +1010,7 @@ public struct Monster: FlatBufferObject {
     }
 
     public static func pack(_ builder: inout FlatBufferBuilder, obj: inout MonsterT) -> Offset<UOffset> {
+        let __pos = obj.pos.map { createVec3(x: $0.x, y: $0.y, z: $0.z, test1: $0.test1, test2: $0.test2, test3a: $0.test3.a, test3b: $0.test3.b) }
         let __name = builder.create(string: obj.name)
         let __inventory = builder.createVector(obj.inventory)
         let __test = obj.test?.pack(builder: &builder) ?? Offset()
@@ -1063,7 +1064,7 @@ public struct Monster: FlatBufferObject {
         let __anyAmbiguous = obj.anyAmbiguous?.pack(builder: &builder) ?? Offset()
         let __vectorOfEnums = builder.createVector(obj.vectorOfEnums)
         let __root = Monster.startMonster(&builder)
-        Monster.add(pos: MyGame.Example.Vec3.pack(&builder, obj: &obj.pos), &builder)
+        Monster.add(pos: __pos, &builder)
         Monster.add(mana: obj.mana, &builder)
         Monster.add(hp: obj.hp, &builder)
         Monster.add(name: __name, &builder)