FlatBuffers 64 for C++ (#7935)

* First working hack of adding 64-bit. Don't judge :)

* Made vector_downward work on 64 bit types

* vector_downward uses size_t, added offset64 to reflection

* cleaned up adding offset64 in parser

* Add C++ testing skeleton for 64-bit

* working test for CreateVector64

* working >2 GiB buffers

* support for large strings

* simplified CreateString<> to just provide the offset type

* generalize CreateVector template

* update test_64.afb due to upstream format change

* Added Vector64 type, which is just an alias for vector ATM

* Switch to Offset64 for Vector64

* Update for reflection bfbs output change

* Starting to add support for vector64 type in C++

* made a generic CreateVector that can handle different offsets and vector types

* Support for 32-vector with 64-addressing

* Vector64 basic builder + tests working

* basic support for json vector64 support

* renamed fields in test_64bit.fbs to better reflect their use

* working C++ vector64 builder

* Apply --annotate-sparse-vector to 64-bit tests

* Enable Vector64 for --annotate-sparse-vectors

* Merged from upstream

* Add `near_string` field for testing 32-bit offsets alongside

* keep track of where the 32-bit and 64-bit regions are for flatbufferbuilder

* move template<> outside class body for GCC

* update run.sh to build and run tests

* basic assertion for adding 64-bit offset at the wrong time

* started to separate `FlatBufferBuilder` into two classes, 1 64-bit aware, the other not

* add test for nested flatbuffer vector64, fix bug in alignment of big vectors

* fixed CreateDirect method by iterating by Offset64 first

* internal refactoring of flatbufferbuilder

* block not supported languages in the parser from using 64-bit

* evolution tests for adding a vector64 field

* conformity tests for adding/removing offset64 attributes

* ensure test is for a big buffer

* add parser error tests for `offset64` and `vector64` attributes

* add missing static that GCC only complains about

* remove stdint-uintn.h header that gets automatically added

* move 64-bit CalculateOffset internal

* fixed return size of EndVector

* various fixes on windows

* add SizeT to vector_downward

* minimze range of size changes in vector and builder

* reworked how tracking if 64-offsets are added

* Add ReturnT to EndVector

* small cleanups

* remove need for second Array definition

* combine IndirectHelpers into one definition

* started support for vector of struct

* Support for 32/64-vectors of structs + Offset64

* small cleanups

* add verification for vector64

* add sized prefix for 64-bit buffers

* add fuzzer for 64-bit

* add example of adding many vectors using a wrapper table

* run the new -bfbs-gen-embed logic on the 64-bit tests

* remove run.sh and fix cmakelist issue

* fixed bazel rules

* fixed some PR comments

* add 64-bit tests to cmakelist

tests/test.cpp

@@ -42,7 +42,7 @@
 #if !defined(_MSC_VER) || _MSC_VER >= 1700
 #  include "arrays_test_generated.h"
 #endif
-
+#include "64bit/offset64_test.h"
 #include "flexbuffers_test.h"
 #include "is_quiet_nan.h"
 #include "monster_test_bfbs_generated.h"  // Generated using --bfbs-comments --bfbs-builtins --cpp --bfbs-gen-embed
@@ -74,7 +74,7 @@ static_assert(flatbuffers::is_same<uint8_t, char>::value ||
 using namespace MyGame::Example;
 
 void TriviallyCopyableTest() {
-// clang-format off
+  // clang-format off
   #if __GNUG__ && __GNUC__ < 5 && \
       !(defined(__clang__) && __clang_major__ >= 16)
     TEST_EQ(__has_trivial_copy(Vec3), true);
@@ -1540,6 +1540,17 @@ void DoNotRequireEofTest(const std::string &tests_data_path) {
 }
 #endif
 
+static void Offset64Tests() {
+  Offset64Test();
+  Offset64SerializedFirst();
+  Offset64NestedFlatBuffer();
+  Offset64CreateDirect();
+  Offset64Evolution();
+  Offset64VectorOfStructs();
+  Offset64SizePrefix();
+  Offset64ManyVectors();
+}
+
 int FlatBufferTests(const std::string &tests_data_path) {
   // Run our various test suites:
 
@@ -1651,6 +1662,7 @@ int FlatBufferTests(const std::string &tests_data_path) {
   NestedStructKeyInStructTest();
   FixedSizedStructArrayKeyInStructTest();
   EmbeddedSchemaAccess();
+  Offset64Tests();
   return 0;
 }
 }  // namespace