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

src/flatc.cpp

@@ -252,10 +252,9 @@ const static FlatCOption flatc_options[] = {
     "Currently this is required to generate private types in Rust" },
   { "", "python-no-type-prefix-suffix", "",
     "Skip emission of Python functions that are prefixed with typenames" },
-  { "", "python-typing", "",
-    "Generate Python type annotations" },
+  { "", "python-typing", "", "Generate Python type annotations" },
   { "", "file-names-only", "",
-    "Print out generated file names without writing to the files"},
+    "Print out generated file names without writing to the files" },
 };
 
 auto cmp = [](FlatCOption a, FlatCOption b) { return a.long_opt < b.long_opt; };
@@ -394,9 +393,11 @@ void FlatCompiler::AnnotateBinaries(const uint8_t *binary_schema,
     const uint8_t *binary =
         reinterpret_cast<const uint8_t *>(binary_contents.c_str());
     const size_t binary_size = binary_contents.size();
+    const bool is_size_prefixed = options.opts.size_prefixed;
 
     flatbuffers::BinaryAnnotator binary_annotator(
-        binary_schema, binary_schema_size, binary, binary_size);
+        binary_schema, binary_schema_size, binary, binary_size,
+        is_size_prefixed);
 
     auto annotations = binary_annotator.Annotate();
 
@@ -663,7 +664,7 @@ FlatCOptions FlatCompiler::ParseFromCommandLineArguments(int argc,
       } else if (arg == "--annotate") {
         if (++argi >= argc) Error("missing path following: " + arg, true);
         options.annotate_schema = flatbuffers::PosixPath(argv[argi]);
-      } else if(arg == "--file-names-only") {
+      } else if (arg == "--file-names-only") {
         // TODO (khhn): Provide 2 implementation
         options.file_names_only = true;
       } else {