Reduced `force_align` in tests to 8, to work with --object-api.

More detail:
https://github.com/google/flatbuffers/projects/6#card-17401359

See also the .md changes in this commit.

Change-Id: Idfa68b2fd3bdb19979833737d3a3cf83ec1d6775

docs/source/CppUsage.md

@@ -208,12 +208,15 @@ The following attributes are specific to the object-based API code generation:
 
 Finally, the following top-level attribute
 
--   native_include: "path" (at file level): Because the `native_type` attribute
+-   `native_include`: "path" (at file level): Because the `native_type` attribute
     can be used to introduce types that are unknown to flatbuffers, it may be
     necessary to include "external" header files in the generated code.  This
     attribute can be used to directly add an #include directive to the top of
     the generated code that includes the specified path directly.
 
+-   `force_align`: this attribute may not be respected in the object API,
+    depending on the aligned of the allocator used with `new`.
+
 # External references.
 
 An additional feature of the object API is the ability to allow you to load

docs/source/Schemas.md

@@ -321,6 +321,9 @@ Current understood attributes:
     these structs to be aligned to that amount inside a buffer, IF that
     buffer is allocated with that alignment (which is not necessarily
     the case for buffers accessed directly inside a `FlatBufferBuilder`).
+    Note: currently not guaranteed to have an effect when used with
+    `--object-api`, since that may allocate objects at alignments less than
+    what you specify with `force_align`.
 -   `bit_flags` (on an enum): the values of this field indicate bits,
     meaning that any value N specified in the schema will end up
     representing 1<<N, or if you don't specify values at all, you'll get

tests/MyGame/Example/Vec3.cs

@@ -28,7 +28,7 @@ public struct Vec3 : IFlatbufferObject
   public Test Test3 { get { return (new Test()).__assign(__p.bb_pos + 26, __p.bb); } }
 
   public static Offset<Vec3> CreateVec3(FlatBufferBuilder builder, float X, float Y, float Z, double Test1, Color Test2, short test3_A, sbyte test3_B) {
-    builder.Prep(16, 32);
+    builder.Prep(8, 32);
     builder.Pad(2);
     builder.Prep(2, 4);
     builder.Pad(1);

tests/MyGame/Example/Vec3.go

@@ -63,7 +63,7 @@ func (rcv *Vec3) Test3(obj *Test) *Test {
 }
 
 func CreateVec3(builder *flatbuffers.Builder, x float32, y float32, z float32, test1 float64, test2 int8, test3_a int16, test3_b int8) flatbuffers.UOffsetT {
-	builder.Prep(16, 32)
+	builder.Prep(8, 32)
 	builder.Pad(2)
 	builder.Prep(2, 4)
 	builder.Pad(1)

tests/MyGame/Example/Vec3.java

@@ -25,7 +25,7 @@ import com.google.flatbuffers.*;
   public Test test3(Test obj) { return obj.__assign(bb_pos + 26, bb); }
 
   public static int createVec3(FlatBufferBuilder builder, float x, float y, float z, double test1, byte test2, short test3_a, byte test3_b) {
-    builder.prep(16, 32);
+    builder.prep(8, 32);
     builder.pad(2);
     builder.prep(2, 4);
     builder.pad(1);

tests/MyGame/Example/Vec3.lua

@@ -35,7 +35,7 @@ function Vec3_mt:Test3(obj)
     return obj
 end
 function Vec3.CreateVec3(builder, x, y, z, test1, test2, test3_a, test3_b)
-    builder:Prep(16, 32)
+    builder:Prep(8, 32)
     builder:Pad(2)
     builder:Prep(2, 4)
     builder:Pad(1)

tests/MyGame/Example/Vec3.php

@@ -78,7 +78,7 @@ class Vec3 extends Struct
      */
     public static function createVec3(FlatBufferBuilder $builder, $x, $y, $z, $test1, $test2, $test3_a, $test3_b)
     {
-        $builder->prep(16, 32);
+        $builder->prep(8, 32);
         $builder->pad(2);
         $builder->prep(2, 4);
         $builder->pad(1);

tests/MyGame/Example/Vec3.py

@@ -28,7 +28,7 @@ class Vec3(object):
 
 
 def CreateVec3(builder, x, y, z, test1, test2, test3_a, test3_b):
-    builder.Prep(16, 32)
+    builder.Prep(8, 32)
     builder.Pad(2)
     builder.Prep(2, 4)
     builder.Pad(1)

tests/monster_test.fbs

@@ -27,7 +27,7 @@ table TestSimpleTableWithEnum (csharp_partial, private) {
   color: Color = Green;
 }
 
-struct Vec3 (force_align: 16) {
+struct Vec3 (force_align: 8) {
   x:float;
   y:float;
   z:float;

tests/monster_test_generated.h

@@ -545,7 +545,7 @@ inline bool operator==(const Test &lhs, const Test &rhs) {
       (lhs.b() == rhs.b());
 }
 
-FLATBUFFERS_MANUALLY_ALIGNED_STRUCT(16) Vec3 FLATBUFFERS_FINAL_CLASS {
+FLATBUFFERS_MANUALLY_ALIGNED_STRUCT(8) Vec3 FLATBUFFERS_FINAL_CLASS {
  private:
   float x_;
   float y_;

tests/monster_test_generated.js

@@ -487,7 +487,7 @@ MyGame.Example.Vec3.prototype.test3 = function(obj) {
  * @returns {flatbuffers.Offset}
  */
 MyGame.Example.Vec3.createVec3 = function(builder, x, y, z, test1, test2, test3_a, test3_b) {
-  builder.prep(16, 32);
+  builder.prep(8, 32);
   builder.pad(2);
   builder.prep(2, 4);
   builder.pad(1);

tests/monster_test_generated.lobster

@@ -118,7 +118,7 @@ struct Vec3 : flatbuffers_handle
         MyGame_Example_Test{ buf_, pos_ + 26 }
 
 def CreateVec3(b_:flatbuffers_builder, x:float, y:float, z:float, test1:float, test2:int, test3_a:int, test3_b:int):
-    b_.Prep(16, 32)
+    b_.Prep(8, 32)
     b_.Pad(2)
     b_.Prep(2, 4)
     b_.Pad(1)

tests/monster_test_generated.rs

@@ -500,8 +500,8 @@ impl Test {
   }
 }
 
-// struct Vec3, aligned to 16
-#[repr(C, align(16))]
+// struct Vec3, aligned to 8
+#[repr(C, align(8))]
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Vec3 {
   x_: f32,

tests/monster_test_generated.ts

@@ -453,7 +453,7 @@ test3(obj?:MyGame.Example.Test):MyGame.Example.Test|null {
  * @returns flatbuffers.Offset
  */
 static createVec3(builder:flatbuffers.Builder, x: number, y: number, z: number, test1: number, test2: MyGame.Example.Color, test3_a: number, test3_b: number):flatbuffers.Offset {
-  builder.prep(16, 32);
+  builder.prep(8, 32);
   builder.pad(2);
   builder.prep(2, 4);
   builder.pad(1);

tests/py_test.py

@@ -90,7 +90,7 @@ def CheckReadBuffer(buf, offset, sizePrefix = False):
     if sizePrefix:
         size = util.GetSizePrefix(buf, offset)
         # taken from the size of monsterdata_python_wire.mon, minus 4
-        asserter(size == 348)
+        asserter(size == 340)
         buf, offset = util.RemoveSizePrefix(buf, offset)
     monster = MyGame.Example.Monster.Monster.GetRootAsMonster(buf, offset)
 

tests/rust_usage_test/tests/integration_test.rs

@@ -656,8 +656,8 @@ mod generated_code_alignment_and_padding {
     }
 
     #[test]
-    fn struct_vec3_is_aligned_to_16() {
-        assert_eq!(16, ::std::mem::align_of::<my_game::example::Vec3>());
+    fn struct_vec3_is_aligned_to_8() {
+        assert_eq!(8, ::std::mem::align_of::<my_game::example::Vec3>());
     }
 
     #[test]