Squashed 'third_party/flatbuffers/' changes from acc9990ab..d6a8dbd26

d6a8dbd26 Experimental fix for failing oss-fuzz coverage build (#6259)
ed391e177 BREAKING: Rust flexbuffers serde human readable set to false (#6257)
a49531414 Update to flags in fuzzing-cmake file (#6256)
de1f0342c Remove _POSIX_C_SOURCE and _XOPEN_SOURCE definitions when compiling o… (#6205)
d0d51e2a5 flatc should support --binary --schema with optional scalar fields. (#6252)
33ab26017 Bump version of rules_go to 0.24.5 (#6234)
febb9d87c Union As Accessors for C# (#6251)
8778dc7c2 Resets buffer without deallocating current pointer (#6247)
aae376e9a Add GetBufferSpan() function to bufferbuilder (#6235)
0ff047148 Modernize android build and sample (#6229)
46a8c7e95 Added required-nested-flatbuffer to monster_test and fixed rust (#6236)
bc56c553e Notify based on Labelling issues and PR (#6241)
07d7cd78a Converted globs to use single quotes (#6240)
cdef70e24 More adjustments to the auto labeler (#6239)
9dd44df35 Updated Lua labeller glob (#6238)
c9b29d088 Support size-prefixed buffers and add tests for size-prefixed messages (#6232)
fba93e0ab Removes duplicate swift in labeler (#6228)
d1a545b1f Added more labels for auto labeler (#6227)
ea92a668d [C#] Optional Scalars (#6217)
6034de286 [Label Bot] Add Java and Kotlin support for the label bot (#6226)
b08b0a440 Implement `Debug` trait for Rust flatbuffers. (#6207)
17ae48dec [Label Bot] Adds some languages to labeler bot (#6222)
fc8097925 Auto Labeler Setup, Just C# for now (#6221)
55658f523 Auto Labeler Setup, Just C# for now (#6218)
14ecfe423 Updated comments and fixed a fundamental type error. (#6214)
a0182cdb1 optional scalars for ts/js (#6215)
0dfcc0a37 Adds NetTest.bat to run .NET Core tests on Windows (#6216)
f9a18ea63 [Java] Implement optional scalars (#6212)
c7586e85a Empties the sharedString map on reset on go and csharp (#6187)
914c64601 Removed C# references from java generator. Move annotations closer to definitions (#6204)
42d7c7997 Adds readable size to asserts in read functions (#6210)
e68e8d7de Refactor idl_gen_rust (#6206)
84809be7e Fix typo in flatbuffers::span declaration. (#6202)
1606fb637 Kotlin test optional enum (#6201)
fe8e3c7e5 Mass Refactoring to use `IsString` and other BASE_TYPE helpers (#6193)
8f6fa4b71 Updated SupportsAdvancedUnionFeatures to look out for string (#6190)
b46db38f5 [JS/TS] Rewrite flexbuffers JS to TS (#6148)
9fa1d2705 Rework enums in rust. (#6098)
a402b3aba idl_gen_json_schema Fix generation of arrays of enums (#6184)
0e1415b99 fix(go_test): remove deprecated grpc call (#6183)
5cd713710 Add generation of JSON Schema to library (#6165)
5be777e1d Bump junit from 4.12 to 4.13.1 in /grpc/tests (#6173)
a49d440ec Bump junit from 4.12 to 4.13.1 in /grpc (#6172)
4ec5e8db9 [C++] Add option to not generate direct copy methods. (#6166)
04bec23a3 Add Array initialization from struct constructor (#5865) (#6147)
77d57fd07 Cast to right type for reserved_ subtraction (#6167)
543c1bbeb Fixed rust nested flatbuffers for tables other than self (#6062)
cb971eece [C++] Fix -Wnarrowing and -Woverflow due to signed bitfields on G++ ARM (#6163)
7b9e61fcc [TS] GRPC  Implementation (#6141)
3359e3042 Moved C++ to optional_scalars2 and added some tests. (#6162)
187a4787f [Rust] Upgrade flatbuffers library to 2018 edition (#6159)
08943aa26 Flatbuffer C++ UnpackTo optimization for vectors of non-bool bytes. (#6154)
5975658eb Enables optional enums in swift (#6160)
5d3cf440e Updated Lobster test for optional bools/enums
8ec8322f0 Ruopt enum (#6156)
bbcc85fd4 Fix generation of C++ code with Optional<Enum> (#6155)
0bdf2fa15 [C#] Fix and improve project files (#6142)
2eedc769d possibility to create a vector from an iterator (#6135)
ab01ae162 flatc should output a warning, when an attribute is attached more than once (#6146)
689bfafa7 [Python/JS/TS] Codegen SizeOf method for structs (#6136)
641309a5b unix2dos on tests/FlatBuffers.Test/FlatBuffers.Core.Test.csproj (#6133)
52e362879 SpanT is available in .Net Standard 2.0. (#6137)
dca12522a Add static cast to avoid implicit double promotion. (#6132)
e0bbaa6f9 [C#]Change to ENABLE_SPAN_T that doesn't require UNSAFE_BYTEBUFFER. (#6073)
ab139d6be Revert "[C#] Fix and improve project files (#6116)" (#6130)
34d67b425 Minireflect fixed array (#6129)
96d5e3597 [JS/TS] fix flatbuffers default export (#6123)
eb686a86f Add missed file generated by optional_scalar.fbs (#6125)
750281630 [C#] Fix and improve project files (#6116)
fb4e1c34f Add CharToLower and CharToUpper into util.s (#6126)
8c67b5b12 Add support of Optional<T> scalars to C++ code generator (#6092)
6228b66d3 [Kotlin] Support for optional scalars. (#6115)
e1be8aaad Bump version for latest swift version (#6121)
94873e595 [JS/TS] Modernize TypeScript / JavaScript flatbuffers support (#6095)
b8e87fafe [JS] Add getFullyQualifiedName() (#6119)
f96d1ef74 [Java] allowing larger buffer sizes when growing a byte buffer (#6118)
89435303b [Swift] Migrates struct write APIS to write directly to the buffer (#6093)
c75ae2429 Optional-ness in reflection (#6097)
338944d3d Rename Nullable scalars to Optional scalars (#6112)
f5ab24bc4 Avoid memcpy call for empty vectors (#6111)
92a8c1a0f [JS] FlexBuffers Fix for wrong type of offset and length values (#6107)
6cea45dcd fix c# json serializer commandline argument docs (#6104)
fec58aa12 Fix for issue 6100: incorrect shrinking logic in ResizeContext() (#6102)
71aca81ff [JS] FlexBuffers Support (#5973)
04d87ffec [C++] Small refactoring of the C++ code generator (#6091)
bb25956f0 Wrap verify file id condition in Check call (#6085)
49f4948f0 + Add `removable-media` plug to the snapcraft config (#6083)
eeacc53d2 Adds proper access types for swift object api & flatbuffers & grpc (#6081)
f3003e08d [Lobster] missed a test
d713a0084 [CMake] enabled multi-core builds in VS projects
77f966f89 [Lobster] optional scalars support
e86d5b8e9 [Kotlin] Attach JvmStatic annotation to each method in companion object (#6052)
db2aa9b4e [C#] Cleaned up .NET testing script for Mono (#6016)
63cc0eec4 Adds a serialize helper function to native table (#6059)
c30a87de6 [TS] Fix four bugs with imported types in TypeScript. (#6054)
a0fb30575 [Swift] Append namespace for Swift Grpc implementation (#6049)
77c18c1d6 export a __version__ variable for python module (#5309)
f1f23d08e adding fb import when no other imports are present (#6030)
f1025b284 [Feature] Checks for Nullable strings (#6050)
5d052f4e5 [Swift] RFC: Switch Swift namespace from public enum to ordinary concat with _ (#6045)
18b015d25 Rust codegen improvements and lint fixes (#6046)
d76e93f27 adds code gen for optional scalars in swift (#6038)
82fac326c [C++] Fix compiler error from deleted assignment operator (#6036) (#6047)
043b52bd4 Optional Scalars support for Rust (#6034)
c8fa0afdf Allow to run cpp tests under grpc/tests/ using bazel. (#6040)
6d0aae73c Fix git command executed in wrong folder when doing cmake superbuild (#6039)
ff1b73128 [Swift] Optional Scalars Preparation (#6028)
2e48c8dd3 tests: Check for both quiet and signaling NaN on mipsel/hppa (#6029)
6942704f2 support deprecated flag in json schema (#6022)
9ecd2e16c Flatc parser support for nullable scalars (#6026)
33e2d8079 [Dart] Generate constant values map for enums (#6025)
969d0f7a6 Using proper symbol name for reexport (#6021)
515a4052a Silence false positive "-Wstringop-overflow" on GCC 10.0 to 11.0 (#6020)
36fbe6f13 Updated FB import (#6019)
b69fc8cc9 [Java] Add support for shared strings on FlatBufferBuilder. (#6012)
ab6af18d9 Not using non-existent create method for obj api (#6015)
37a5dee10 Code cleanup + updates test and readme (#6004)
8a721f69a Serde with bytes maps to Blob (#6009)
e810635ea [Swift] FlatBuffers createMonster method doesn't treat struct properly (#5992)
4995e1527 Manage grpc dependency in Bazel's WORKSPACE file. (#5995)
60b6066fe Add warning to schema parser if field name is not snake_case. (#6005)
35d45cac7 [Rust] Flexbuffers dependency cleanup and fixes (#5998)
165a6e3d1 Re-added Evolution Schema Code Generation Command (#5999)
13d3fb2ea Fix RPM install conflict (#6003)
d64078eb2 [Swift] Initialize memory when clear ByteBuffer (#5982)
ca1190a3d [TS] Use proper TypedArray in create*Vector (#5991)
7571b2ac5 [C++] Updates real_path to be truly portable (#5787)
e5a8f76a4 [C++] Generate default member initializers for >= C++11 (#5989)
413bb9b55 [Kotlin] Fix Access to union of vector element (#5994)
f35184aef [Swift] Add parsing from unowned UnsafeMutableRawPointer for ByteBuffer (#5981)
b124b7625 Removed requirement that enums be declared in ascending order. (#5887)
0ec7600c6 Do not remove the last digit from float values (#5974)
14baf45c9 Mark GetBufferMinAlignment() const (#5985)
9abb2ec2c TypeScript/JavaScript docs improvements (#5984)
2e57d80b1 [Swift] Internal library improvements (#5965)
cfc7753a4 [Doc] Added missing letters to compiler options (#5976)
12ddc8a92 Rust Flexbuffers Documentation update (#5979)
24ad35709 [docs] typo: updates monsterdata.json to be valid json (#5978)
cc44a4442 [idl_parser] Mark typefield as deprecated (#5958)
9ab4a5c0e Deleted old stale bot
6682cfe87 Increased Operations per run in stale.yml
64922904b Adding Stale Action to clean up PR and Issues
8e505cb67 [C++] Fixed/Enabled --cpp-ptr-type std::shared_ptr [#5813] (#5959)
a28357d7a Propagate boolean default values from proto to fbs (#5964)
7cb4762a6 [Swift] Improving reallocation time by using memcpy and moving reallocation code to storage (#5960)
4e45f7c9e Fix error in SimpleQSort (#5955)
7ac026405 fix error on GRPC Python - ignore namespace tree if not specified (#5862) (#5922)
108e981db Required is now implemented in swift (#5952)
94a78e385 Fixed: Access violation and ASAN/UNSAN failures with sorted tables
53fb453e0 [rust] Add FlatBufferBuilder::force_defaults API (#5946)
17c1f35fa [FlexBuffer][Java] ReadWriteBuf and ReadBuf interface public (#5948)
2eaf57778 [Java] Grow ArrayReadWriteBuf enough to match requested capacity. (#5921)
666800da3 Adds bool support in structs + updates grpc support + CI upgrades (#5943)
38ed69eb3 fixed mutating inline values (#5942)
d026e6f07 Add static asserts to ensure that reflection API arrays are kept in sync (#5934)
988164f6e [C++] Got rid of memset's in constructors (#5938)
7179a5a8b General Codebase clean up (#5939)
a0da0c08c Add GetStringView like GetString, GetCstring (#5937)
ac203b209 [C#] Add file identifier to ObjectAPI Serialization Utility. (#5920)
8dd1bf25b not creating creation methods when using structs (#5919)
5aa443d98 [Dart] Adding FlexBuffers support (#5853)
0fa087657 [Dart] Getting tests/DartTest.sh to work on master. (#5915)
424a473e1 Schema parser: prohibit declaration of an array of pointers inside structs (#5907)
c3faa8346 Fix Cargo.toml dependencies (#5911)
91399ad05 fix union type names (#5902)
32782e4ad Update Rust Flexbuffers metadata before publishing (#5905)
e7f3b1690 [TS] Make Obj-API work with --short-names (#5898)
12ed1fe4a fixed invalid imports with --gen-all (#5895)
85ee4df7a [C#] Thread safe reads of Double and Float values from a ByteBuffer (#5900)
de89bd193 Implement flexbuffers in python (#5880)
8be05f6bd Rust Flexbuffers (#5669)
870ecbc09 [swift] Moves code to use VTablesStorage (#5888)
c2da8d5d8 [Java][FlexBuffers] Make FlexBuffersBuilder reusable by adding clear() (#5889) (#5890)
e84cbff67 Align package name to FindFlatBuffers.cmake (#5899)
f94e6c84e Small tutorial improvements - documentation only (#5894)
f12cca8bc Attempt at adding Github Actions CI
7e4124d6e Handle git program or .git folder absence (#5878)
a875d247a only add native_include_files if object based api is enabled (#5886)
6e9f5d981 Respect shared attribute in Parser (#5885)
ff1c78233 include/flatbuffers: typo fixes in comments (#5884)
2e9a19673 Updates swift docs for package management (#5883)
e3cb07d32 [Rust] idl_gen_rust.cpp: (Option/required-aware codegen for unions) (#5850)
712866d57 Propagate use_string_pooling in CopyTable (#5879)
44c919a9e Not using reexports with --gen-all (#5873)
99aa1ef21 Added INCLUDE_PREFIX option for flatbuffers_generate_headers (#5866)
40ba170c9 Fixed text in internals doc that implied structs can be root
cb4d0f72e [Swift] Object API support  (#5826)
003e16405 [TS] Add Obj API (#5788)
21cf300f4 fix cpp usage markdown error (#5845)
9655e12d6 Upgraded swift implementation for grpc (#5843)
fb96fadc2 [C#] Fix nested structs and arrays in Object API (#5765)
408f11fbd [ts] Fix empty source/dest namespaces when reexporting. (#5841)
a83caf591 Improves performance for the swift library by using structs + a storage class (#5835)
925fab6b1 [Java][FlexBuffers] Optimize Map access (#5735)
d9fecc332 [CMake] : Add precompiled header support with FLATBUFFERS_ENABLE_PCH (#5827)
e9d453240 Added flatbuffers_generate_headers and flatbuffers_generate_binary_files cmake functions. (#5830)
c37c989ed Correct calculation of vector element size (#5831)
6b271b7ec Fix Clang-trunk warnings about special members deprecated in C++20. (#5829)
90f3b8e8c Fix `float_constant` definition in './doc/Grammar.md` (#5828)
3af735934 [csharp] flatc should generate a 'Create…' method for tables with struct field… (#5818)
c4231c3cb Updated doxyfile - added missing files (#5824)
9657df184 Update Grammar.md (#5820)
97ffc590e Include CPack only when explictly packaging (#5817)
8b52af65b [C++] Add max_depth and max_tables parameters to reflection::Verify (#5815)
9b034eee1 Fix interpretation of 'nan(number)' by the idl_parser (#5810)
3e9ac3cff [Scripts] Adds swift to generated code (#5806)
697147a2e updated maven build files
6df40a247 pre-tag version bump for 1.12
0dba63909 Removes the inner loop in the endtable check written tables (#5803)
0e3fdd0ee Escape characters in jsonschema descriptions (#5644)
45a2b07cb Remove `noexcept` qualifier copy-ctor of `union` type (#5800) (#5802)
d10c16314 Replace 'assert' by 'FLATBUFFERS_ASSERT' inside idl_parser.cpp (#5799)
35abb7f89 Add non-nullable modifier to return type of functions never returning null (#5797)
9954e09ab [C++] Generate code for vector force_align attribute. (#5796)
95a21327f rust: pub export the VectorIter type (#5736)
89b6183ee Fix Python min alignment
5a98d65e8 [Rust] Add gen-name-strings for Rust (#5757)
f73d205bc Removed assert that wasn't backwards compatible.
7c37abe92 [C#] add ObjectAPI Serialization Utility (#5785)
4749e77b0 Fixed docs on how to obtain parser error.
6ff189841 Added --filename-suffix and --filename-ext to flatc (#5778)
c9a30c9ca Fixed refractoring issue in reflection/generate_code.sh. Also, mv deletes the original file, so I don't need to clean it up manually in that case. (#5777)
8c02d17be Skip writing reflection_generated.h if not changed (#5776)
34305c4ce [Swift] Adds GRPC to Swift (#5758)
cd88e6b2a [Java][FlexBuffers] Abstract buffer access from ByteBuffer (#5743)
3ec7a53c6 Adds cocoapods and a readme of how to get the package (#5771)
6d44cede7 [snap] Fix versioning (#5727)
cc08c0835 [Python] Fixed potential allignment issue (#5768)
54f8b787c Fix memory leak on cpp object api (#5761)
17557f913 [Python] Fixed issue #5499 (#5764)
d54af8cd4 [C++] Use strong enum type for vectors when scoped-enums is on. (#5750)
173e10fdf [C#] support Json Serialization (#5752)
8f56990f6 FlexBuffers: C++: scalar-only typed vectors were not aligned.
6400c9b05 Bump Rust port to 0.6.1 (#5747)
7418d8587 [C#] support Object API (#5710)
c580fa284 Adds min and max, comments, and all of swift's keywords + fix docs (#5737)
f2a127230 Use VS 2017 and 2019 on CI, fix cast issue in dart_idl (#5740)
316d7c208 Creates a flatbuffers validation function + small fix (#5725)
47026ea6b Added the code to embed the binary schema to the source (--bfbs-gen-embed). (#5701)
3f677f241 [Java][FlexBuffers] Deprecate typed vector strings due to design flaw (#5722)
a593a11e5 [Go] Implements a SharedStrings function (#5733)
7cdfc8475 [Swift] Fix padding function overflow when bufSize is 0 (#5721)
bab2b0db4 Add vcpkg installation instructions (#5732)
89418eb84 [Dart] Fix deprecated field support, inf/nan (#5724)
9cadf05d8 [typescript] Size-prefixed root accessors not taking into account size prefix (#5717)
6da1cf79d [rust] Add use declarations to Rust-generated bindings for imported FB definitions (#5645)
bee1df96d [Go] Replace references to hardcoded ”Monster" etc with idiomatic go wherever possible (#5716)
01189d7ed [C++] Fix for printing of enum in case output_enum_identifiers=1. (#5706)
c4b2b0a25 [Swift] Support create long string (#5709)
a4b2884e4 Added create function for swift (#5707)
04d80f255 [Swift] Swift implementation 🎉🎉 (#5603)
55686100a Changed direct calls to strtod to use StringToNumber
718351831 Document JSON compatibility guarantees. (#5704)
d1b34f0f2 Add CMake 'generated_code' target to simplify resolution of build dependencies (#5697)
21b706196 (Optionally) add an additional suffix namespace to generated fbs files. (#5698)
35daaf83d [Java] Replace Table.UTF8_CHARSET with StandardCharsets.UTF_8 (#5696)
3b458f7a1 Rust: Temporarily disable 2 endianness unit tests (#5695)
a5d9d0f7d [C++17] Add Traits class for Tables and Factory function within it. (#5678)
3cd9b6434 Removed code_generators.cpp from library targets
355dfd48d [rust] Make enum names public (#5690)
bcd58a159 Correct inverted logic around include prefixes. (#5689)
a2c12900a Optimize Pack method using numpy (#5662)
901b89e73 [C++] Add Builder and Table typedefs (#5685)
31f879908 Minor doc updates: FlexBuffers C#, Discord, CppUsage.
8023d99e2 Upgrade rules_go (#5684)
b4154405d Fix --incompatible_load_cc_rules_from_bzl (#5683)
04c17c7a7 Add support for absl::string_view when available (#5682)
62ec7d52c [Bazel] Add support for compatible_with and restricted_to (#5681)
7de668053 CI: New Docker tests for Python with numpy (#5677)
3a70e0b30 Fixed struct initialization error on older versions of C#
9b1320135 Fixed warnings in FlexBuffers.java
5e3916050 Fixed out of date licenses on gRPC Python files.
c95755051 Removed test proto output.
44bf71988 Add flatc '--cpp_std' switch (#5656)
3e8f15df9 Fix for FlexBuffers FBT_VECTOR_STRING size bit-width.
602721a73 Added Check to VerifyAlignment (#5675)
13c05f4da Improve import handling for proto conversion (#5673)
ce3a1c43a [Dart] Fix prepare space for writeListInt64 and writeListUint64 (#5654)
aa75e5734 Make Rust constants public (#5659)
2790fee25 Add namespace qualification to union types (#5666)
eddebec1b Bugfix for Rust generation of union fields named with language keywords (#5592)
030fee36a wrap multiple statements in do {} while(!IsConstTrue(true)) (#5655)
f9724d1bd [gRPC] Uncomment MessageBuilder (#5658)
b20801ca4 Supress unsigned-integer-overflow for PaddingBytes (#5647)
a8e800bd7 Add --force-empty-vectors option (#5653)
d7530ae96 Fixed enum min/max values not properly escaped.
99d11e279 Split Bazel targets into multiple packages (#5640)
4fd8eb214 Remove a static_assert (#5643)
65f870357 Flatbuffers Python Object API (#5616)
75823cc27 [Clang 10]: definition of implicit copy constructor for 'TableKeyComparatoris deprecated #5649 (#5650)
58e279244 [docs]: add missing semicolon (#5648)
3c964e10a [GO] Fix support for enums with underscores and Unions with imported members (#5600)
c3c32ec94 Fix ambiguity of a type deduction in TEST_EQ macro if arguments have `enum class` type. (#5630)
075e8d676 Simplify declarations of x-macro FLATBUFFERS_TD (#5638)
bcf1bd5c9 read vtable size through ReadScalar() (#5636)
136d75fa6 Changed null checks in test. Removed verifier pointer usage (#5634)
091fa1fd1 Add testing of C++ with sanitizers (CI-Docker) (#5631)
ff3781dc2 add namespace prefix in FLATBUFFERS_MAX_BUFFER_SIZE (#5629)
6beb9f49c Support for python grpc - continuing the work from the pull request #4270 #4705 (#5613)
80988ea86 Removed idl_gen_general.cpp and move contents to code_generators.cpp (#5625)
0f2ff7eaa Lua cleanup (#5624)
dda095023 [C++] Adds basic schema evolution tests (#5611)
adbcbba5d [C++, C#, Java] Separated C# and Java generators into their own classes (#5618)
cbbd6aca0 add check for root_type specified for json schema generation (#5622)
405c64e07 [Rust] Bump smallvec version to 1.0 (#5621)
42c08cbca Ran src/clang-format-all.sh (#5617)
33d5dd9bd Improved pull request & clang-format instructions.
105dd528e Change monster_extra generation to use flatbuffers::unique_ptr (#5612)
f0f0efe7b [C++] Refactor to conform to Google C++ style guide (#5608)
e837d5a29 Fixed deprecated method in GRPC Java test.
9834ee978 Fixed Apache license not using canonical version.
44b2ab087 include/flatbuffers/base.h: fix no_sanitize issue with old clang (#5610)
46ae3f80a [C++, Java, C#, TypeScript, JavaScript] Skip generation of mutable union types (#5599)
7b38aa71e flatbuffers.h: fix documentation warning (#5607)
661bedd83 Add Lua FlatbufferBuilder Clean() method to enable reuseable builders (#5606)
8526e12d7 [Kotlin] Fix union vector accessor after change in Java API (#5605)
3c7b660d6 [flatc] Remove an always true condition for flexbuffers (#5604)
964365ba6 [Go] Add UnPackTo functions (#5598)
32254b7ac [Go] Object API support (#5339)
521e255ad Rust: Add idiomatic iterator for Vector type (#5579)
1b85292fd Fix typos in comments (#5590)
480815447 C++ verifier for evolved union fields should return true (#5586)
8d5e424c6 Add ByteBuffer copy for vector of bytes in Java (#5587)
b4774d235 Rust: Fix Copy and Clone impls for a few generic types (#5577)
26f238c24 Add `--clean-first` to the cmake-build command (travis) (#5574)
e93c8c46e Fix Follow implementation for bool (#5554)
e21516b9d Fix issue #5557 (#5573)
fbc11e8ae Avoid intentional unsigned integer overflow getting caught by sanitizers (#5572)
e9d29c21a Python: Add forceDefaults opt to python Builder (#5564)
8bfafc76d Java: Don't annotate vector-of-tables item getters with @nullable. (#5562)
df3e8bf4a Fixed warnings generated by recent JSON sorting feature.
5665cfe49 [Java] byte buffer factory returned buffer capcity is used instead of the requested size (#5558)
5797540ed #5544 Fix of Array of table is not sorted if Create<type>Direct() is used (#5546)
7f1af7cb0 Fix build with gcc version 7.4.0 (#5570)
32f47ad24 Fixed JSON parser not sorting vectors of tables/structs with key.
842f672ba [FlexBuffers][Java] Cache size of Sized objects in FlexBuffers (#5551)
d4cae0a62 Fix issue #5542 (#5543)
f1147f65b Fixed Android STLPort related error.
69d3fec48 Fix namespaced struct/field name collision detection (#5540) (#5545)
cfb4ecf6f [flac] Add FlexBuffers option for generating data (#5519)
a92039687 Update Rust versions under test from 1.30.1 to 1.37.0 (#5538)
625338d09 Adds XOPEN_SOURCE for PATH_MAX and POSIX 1993 for stat (#5529)
3f8ce99c5 [FlexBuffers][Java] Add override Key::toString (#5533)
0798b7b69 [FlexBuffers][Java] Fix wrong access to a string using Reference::asString(). (#5532)
cbdf82e2f Fix Mutate() methods of Array<scalar/struct> (override 5508) (#5526)
e365c502f Java: Added access object for vector of struct and vector of tables. (#5233)
97f3aa917 Fixed DetachedBuffer self move assignment (#5521)
2f5bb2eec Fix buildifier warnings found in new bazel (#5517)
917687c7a Fixed Reflection Verifier not handling vectors of unions.
f9277e691 Fixed GenerateText not handling vectors of unions.
2706381ee Add element size parameter to __vector_as_arraysegment [c#] (#5512)
b5560fcd5 [Java][FlexBuffers] Improve documentation for FlexBuffers in Java. (#5506)
782b865c5 Annotate getters with @Pure when --java-checkerframework is specified. (#5510)
3bfc86eaf [Dart]fix: segment fault with empty namespace when generating dart file (#5507)
c0282873f Rust: Fixed cargo clippy on non-generated code (#5485)
4b870aca9 [Javascript] Fix syntax error for signed enum (#5503)
d0e3870c0 [C#] Fix retrieving enumeration vectors as arrays (#5457)
fb25eb87f Doc typo fixes (#5505)
cb35d3a0e Use all of the available space in the buffer returned by ByteBufferFactory to allow the factory to keep a pool of larger than initialsize sized buffers. (#5500)
8e6cabb31 [FlexBuffers][Java] Implementation of FlexBuffers API (#5476)
bd31dd242 Clarified value reuse in FlexBuffers
65b67d213 Fixed test build invocation of arrays_test.fbs
1fbb71132 FlexBuffers: allow any values to be shared.
cd75a3658 Android: remove app_dummy() calls
ec6b0bf29 Fixed STLPort Android compile error
c11b5d744 [bugfix]flexbuffers isvector bugfix (#5488)
4525c91be Fix incorrect padding in arrays of structs (Issue #5484) (#5491)
b97b342f5 Fixed missing generated code.
c1058a903 C++ IDL generation adds superfluous semicolon in GenTablePost, causing (#5483)
303044934 [go]add Name() for ForceCodec  interface (#5486)
a2485d4ec reflection: check for valid union enum value during object verification (#5475)
a20e71ac9 has_method support for primitive fields in java runtime. Changed: idl.h, FlatBufferBuilder.java ,  idl_gen_general.cpp, idl_parser.cpp, flatc.cpp (#5468)

Change-Id: I836f4b43e6818bb16425a87899e6234ac86242aa
git-subtree-dir: third_party/flatbuffers
git-subtree-split: d6a8dbd26ff08a8868e0d0c1b4b67d31b40e4a7f
diff --git a/include/flatbuffers/base.h b/include/flatbuffers/base.h
index d98da13..085099a 100644
--- a/include/flatbuffers/base.h
+++ b/include/flatbuffers/base.h
@@ -46,14 +46,17 @@
 #include <iterator>
 #include <memory>
 
+#if defined(__unix__) && !defined(FLATBUFFERS_LOCALE_INDEPENDENT)
+  #include <unistd.h>
+#endif
+
 #ifdef _STLPORT_VERSION
   #define FLATBUFFERS_CPP98_STL
 #endif
-#ifndef FLATBUFFERS_CPP98_STL
-  #include <functional>
-#endif
 
-#include "flatbuffers/stl_emulation.h"
+#ifdef __ANDROID__
+  #include <android/api-level.h>
+#endif
 
 #if defined(__ICCARM__)
 #include <intrinsics.h>
@@ -99,7 +102,7 @@
 #if !defined(__clang__) && \
     defined(__GNUC__) && \
     (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__ < 40600)
-  // Backwards compatability for g++ 4.4, and 4.5 which don't have the nullptr
+  // Backwards compatibility for g++ 4.4, and 4.5 which don't have the nullptr
   // and constexpr keywords. Note the __clang__ check is needed, because clang
   // presents itself as an older GNUC compiler.
   #ifndef nullptr_t
@@ -140,7 +143,7 @@
 #endif // !defined(FLATBUFFERS_LITTLEENDIAN)
 
 #define FLATBUFFERS_VERSION_MAJOR 1
-#define FLATBUFFERS_VERSION_MINOR 11
+#define FLATBUFFERS_VERSION_MINOR 12
 #define FLATBUFFERS_VERSION_REVISION 0
 #define FLATBUFFERS_STRING_EXPAND(X) #X
 #define FLATBUFFERS_STRING(X) FLATBUFFERS_STRING_EXPAND(X)
@@ -154,10 +157,12 @@
     defined(__clang__)
   #define FLATBUFFERS_FINAL_CLASS final
   #define FLATBUFFERS_OVERRIDE override
+  #define FLATBUFFERS_EXPLICIT_CPP11 explicit
   #define FLATBUFFERS_VTABLE_UNDERLYING_TYPE : flatbuffers::voffset_t
 #else
   #define FLATBUFFERS_FINAL_CLASS
   #define FLATBUFFERS_OVERRIDE
+  #define FLATBUFFERS_EXPLICIT_CPP11
   #define FLATBUFFERS_VTABLE_UNDERLYING_TYPE
 #endif
 
@@ -165,13 +170,16 @@
     (!defined(__GNUC__) || (__GNUC__ * 100 + __GNUC_MINOR__ >= 406)) || \
     (defined(__cpp_constexpr) && __cpp_constexpr >= 200704)
   #define FLATBUFFERS_CONSTEXPR constexpr
+  #define FLATBUFFERS_CONSTEXPR_CPP11 constexpr
+  #define FLATBUFFERS_CONSTEXPR_DEFINED
 #else
   #define FLATBUFFERS_CONSTEXPR const
+  #define FLATBUFFERS_CONSTEXPR_CPP11
 #endif
 
 #if (defined(__cplusplus) && __cplusplus >= 201402L) || \
     (defined(__cpp_constexpr) && __cpp_constexpr >= 201304)
-  #define FLATBUFFERS_CONSTEXPR_CPP14 FLATBUFFERS_CONSTEXPR
+  #define FLATBUFFERS_CONSTEXPR_CPP14 FLATBUFFERS_CONSTEXPR_CPP11
 #else
   #define FLATBUFFERS_CONSTEXPR_CPP14
 #endif
@@ -194,12 +202,22 @@
   #define FLATBUFFERS_DELETE_FUNC(func) private: func;
 #endif
 
+// Check if we can use template aliases
+// Not possible if Microsoft Compiler before 2012
+// Possible is the language feature __cpp_alias_templates is defined well
+// Or possible if the C++ std is C+11 or newer
+#if (defined(_MSC_VER) && _MSC_VER > 1700 /* MSVC2012 */) \
+    || (defined(__cpp_alias_templates) && __cpp_alias_templates >= 200704) \
+    || (defined(__cplusplus) && __cplusplus >= 201103L)
+  #define FLATBUFFERS_TEMPLATES_ALIASES
+#endif
+
 #ifndef FLATBUFFERS_HAS_STRING_VIEW
   // Only provide flatbuffers::string_view if __has_include can be used
   // to detect a header that provides an implementation
   #if defined(__has_include)
     // Check for std::string_view (in c++17)
-    #if __has_include(<string_view>) && (__cplusplus >= 201606 || _HAS_CXX17)
+    #if __has_include(<string_view>) && (__cplusplus >= 201606 || (defined(_HAS_CXX17) && _HAS_CXX17))
       #include <string_view>
       namespace flatbuffers {
         typedef std::string_view string_view;
@@ -212,6 +230,13 @@
         typedef std::experimental::string_view string_view;
       }
       #define FLATBUFFERS_HAS_STRING_VIEW 1
+    // Check for absl::string_view
+    #elif __has_include("absl/strings/string_view.h")
+      #include "absl/strings/string_view.h"
+      namespace flatbuffers {
+        typedef absl::string_view string_view;
+      }
+      #define FLATBUFFERS_HAS_STRING_VIEW 1
     #endif
   #endif // __has_include
 #endif // !FLATBUFFERS_HAS_STRING_VIEW
@@ -229,10 +254,8 @@
 
 #ifndef FLATBUFFERS_LOCALE_INDEPENDENT
   // Enable locale independent functions {strtof_l, strtod_l,strtoll_l, strtoull_l}.
-  // They are part of the POSIX-2008 but not part of the C/C++ standard.
-  // GCC/Clang have definition (_XOPEN_SOURCE>=700) if POSIX-2008.
   #if ((defined(_MSC_VER) && _MSC_VER >= 1800)            || \
-       (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE>=700)))
+       (defined(_XOPEN_VERSION) && (_XOPEN_VERSION>=700)) && (!defined(__ANDROID_API__) || (defined(__ANDROID_API__) && (__ANDROID_API__>=21))))
     #define FLATBUFFERS_LOCALE_INDEPENDENT 1
   #else
     #define FLATBUFFERS_LOCALE_INDEPENDENT 0
@@ -242,7 +265,7 @@
 // Suppress Undefined Behavior Sanitizer (recoverable only). Usage:
 // - __supress_ubsan__("undefined")
 // - __supress_ubsan__("signed-integer-overflow")
-#if defined(__clang__)
+#if defined(__clang__) && (__clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >=7))
   #define __supress_ubsan__(type) __attribute__((no_sanitize(type)))
 #elif defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 409)
   #define __supress_ubsan__(type) __attribute__((no_sanitize_undefined))
@@ -296,12 +319,13 @@
 typedef uintmax_t largest_scalar_t;
 
 // In 32bits, this evaluates to 2GB - 1
-#define FLATBUFFERS_MAX_BUFFER_SIZE ((1ULL << (sizeof(soffset_t) * 8 - 1)) - 1)
+#define FLATBUFFERS_MAX_BUFFER_SIZE ((1ULL << (sizeof(::flatbuffers::soffset_t) * 8 - 1)) - 1)
 
 // We support aligning the contents of buffers up to this size.
 #define FLATBUFFERS_MAX_ALIGNMENT 16
 
 #if defined(_MSC_VER)
+  #pragma warning(disable: 4351) // C4351: new behavior: elements of array ... will be default initialized
   #pragma warning(push)
   #pragma warning(disable: 4127) // C4127: conditional expression is constant
 #endif
@@ -330,22 +354,20 @@
   if (sizeof(T) == 1) {   // Compile-time if-then's.
     return t;
   } else if (sizeof(T) == 2) {
-    union { T t; uint16_t i; } u;
-    u.t = t;
+    union { T t; uint16_t i; } u = { t };
     u.i = FLATBUFFERS_BYTESWAP16(u.i);
     return u.t;
   } else if (sizeof(T) == 4) {
-    union { T t; uint32_t i; } u;
-    u.t = t;
+    union { T t; uint32_t i; } u = { t };
     u.i = FLATBUFFERS_BYTESWAP32(u.i);
     return u.t;
   } else if (sizeof(T) == 8) {
-    union { T t; uint64_t i; } u;
-    u.t = t;
+    union { T t; uint64_t i; } u = { t };
     u.i = FLATBUFFERS_BYTESWAP64(u.i);
     return u.t;
   } else {
     FLATBUFFERS_ASSERT(0);
+    return t;
   }
 }
 
@@ -369,6 +391,13 @@
   return EndianScalar(*reinterpret_cast<const T *>(p));
 }
 
+// See https://github.com/google/flatbuffers/issues/5950
+
+#if (FLATBUFFERS_GCC >= 100000) && (FLATBUFFERS_GCC < 110000)
+  #pragma GCC diagnostic push
+  #pragma GCC diagnostic ignored "-Wstringop-overflow"
+#endif
+
 template<typename T>
 // UBSAN: C++ aliasing type rules, see std::bit_cast<> for details.
 __supress_ubsan__("alignment")
@@ -381,9 +410,14 @@
   *reinterpret_cast<uoffset_t *>(p) = EndianScalar(t.o);
 }
 
+#if (FLATBUFFERS_GCC >= 100000) && (FLATBUFFERS_GCC < 110000)
+  #pragma GCC diagnostic pop
+#endif
+
 // Computes how many bytes you'd have to pad to be able to write an
 // "scalar_size" scalar if the buffer had grown to "buf_size" (downwards in
 // memory).
+__supress_ubsan__("unsigned-integer-overflow")
 inline size_t PaddingBytes(size_t buf_size, size_t scalar_size) {
   return ((~buf_size) + 1) & (scalar_size - 1);
 }
diff --git a/include/flatbuffers/code_generators.h b/include/flatbuffers/code_generators.h
index 0bcec91..d64ab03 100644
--- a/include/flatbuffers/code_generators.h
+++ b/include/flatbuffers/code_generators.h
@@ -19,6 +19,7 @@
 
 #include <map>
 #include <sstream>
+
 #include "flatbuffers/idl.h"
 
 namespace flatbuffers {
@@ -60,7 +61,7 @@
   }
 
   // Appends the given text to the generated code as well as a newline
-  // character.  Any text within {{ and }} delimeters is replaced by values
+  // character.  Any text within {{ and }} delimiters is replaced by values
   // previously stored in the CodeWriter by calling SetValue above.  The newline
   // will be suppressed if the text ends with the \\ character.
   void operator+=(std::string text);
@@ -75,6 +76,8 @@
     if (cur_ident_lvl_) cur_ident_lvl_--;
   }
 
+  void SetPadding(const std::string &padding) { pad_ = padding; }
+
  private:
   std::map<std::string, std::string> value_map_;
   std::stringstream stream_;
@@ -93,16 +96,20 @@
   static std::string NamespaceDir(const Parser &parser, const std::string &path,
                                   const Namespace &ns);
 
+  std::string GeneratedFileName(const std::string &path,
+                                const std::string &file_name,
+                                const IDLOptions &options) const;
+
  protected:
   BaseGenerator(const Parser &parser, const std::string &path,
-                const std::string &file_name,
-                std::string qualifying_start,
-                std::string qualifying_separator)
+                const std::string &file_name, std::string qualifying_start,
+                std::string qualifying_separator, std::string default_extension)
       : parser_(parser),
         path_(path),
         file_name_(file_name),
         qualifying_start_(qualifying_start),
-        qualifying_separator_(qualifying_separator) {}
+        qualifying_separator_(qualifying_separator),
+        default_extension_(default_extension) {}
   virtual ~BaseGenerator() {}
 
   // No copy/assign.
@@ -138,6 +145,7 @@
   const std::string &file_name_;
   const std::string qualifying_start_;
   const std::string qualifying_separator_;
+  const std::string default_extension_;
 };
 
 struct CommentConfig {
diff --git a/include/flatbuffers/flatbuffers.h b/include/flatbuffers/flatbuffers.h
index 1a250cd..8683832 100644
--- a/include/flatbuffers/flatbuffers.h
+++ b/include/flatbuffers/flatbuffers.h
@@ -18,9 +18,14 @@
 #define FLATBUFFERS_H_
 
 #include "flatbuffers/base.h"
+#include "flatbuffers/stl_emulation.h"
+
+#ifndef FLATBUFFERS_CPP98_STL
+  #include <functional>
+#endif
 
 #if defined(FLATBUFFERS_NAN_DEFAULTS)
-#include <cmath>
+#  include <cmath>
 #endif
 
 namespace flatbuffers {
@@ -43,6 +48,20 @@
 }
 #endif
 
+// Check 'v' is out of closed range [low; high].
+// Workaround for GCC warning [-Werror=type-limits]:
+// comparison is always true due to limited range of data type.
+template<typename T>
+inline bool IsOutRange(const T &v, const T &low, const T &high) {
+  return (v < low) || (high < v);
+}
+
+// Check 'v' is in closed range [low; high].
+template<typename T>
+inline bool IsInRange(const T &v, const T &low, const T &high) {
+  return !IsOutRange(v, low, high);
+}
+
 // Wrapper for uoffset_t to allow safe template specialization.
 // Value is allowed to be 0 to indicate a null object (see e.g. AddOffset).
 template<typename T> struct Offset {
@@ -203,11 +222,10 @@
   const uint8_t *data_;
 };
 
-template<typename Iterator> struct VectorReverseIterator :
-  public std::reverse_iterator<Iterator> {
-
-  explicit VectorReverseIterator(Iterator iter) :
-    std::reverse_iterator<Iterator>(iter) {}
+template<typename Iterator>
+struct VectorReverseIterator : public std::reverse_iterator<Iterator> {
+  explicit VectorReverseIterator(Iterator iter)
+      : std::reverse_iterator<Iterator>(iter) {}
 
   typename Iterator::value_type operator*() const {
     return *(std::reverse_iterator<Iterator>::current);
@@ -277,10 +295,14 @@
   const_iterator end() const { return const_iterator(Data(), size()); }
 
   reverse_iterator rbegin() { return reverse_iterator(end() - 1); }
-  const_reverse_iterator rbegin() const { return const_reverse_iterator(end() - 1); }
+  const_reverse_iterator rbegin() const {
+    return const_reverse_iterator(end() - 1);
+  }
 
   reverse_iterator rend() { return reverse_iterator(begin() - 1); }
-  const_reverse_iterator rend() const { return const_reverse_iterator(begin() - 1); }
+  const_reverse_iterator rend() const {
+    return const_reverse_iterator(begin() - 1);
+  }
 
   const_iterator cbegin() const { return begin(); }
 
@@ -348,6 +370,7 @@
   // This class is a pointer. Copying will therefore create an invalid object.
   // Private and unimplemented copy constructor.
   Vector(const Vector &);
+  Vector &operator=(const Vector &);
 
   template<typename K> static int KeyCompare(const void *ap, const void *bp) {
     const K *key = reinterpret_cast<const K *>(ap);
@@ -378,6 +401,7 @@
 
  private:
   VectorOfAny(const VectorOfAny &);
+  VectorOfAny &operator=(const VectorOfAny &);
 };
 
 #ifndef FLATBUFFERS_CPP98_STL
@@ -402,22 +426,36 @@
 
 // This is used as a helper type for accessing arrays.
 template<typename T, uint16_t length> class Array {
- public:
-  typedef VectorIterator<T, typename IndirectHelper<T>::return_type>
-      const_iterator;
-  typedef VectorReverseIterator<const_iterator> const_reverse_iterator;
+  typedef
+      typename flatbuffers::integral_constant<bool,
+                                              flatbuffers::is_scalar<T>::value>
+          scalar_tag;
+  typedef
+      typename flatbuffers::conditional<scalar_tag::value, T, const T *>::type
+          IndirectHelperType;
 
-  typedef typename IndirectHelper<T>::return_type return_type;
+ public:
+  typedef uint16_t size_type;
+  typedef typename IndirectHelper<IndirectHelperType>::return_type return_type;
+  typedef VectorIterator<T, return_type> const_iterator;
+  typedef VectorReverseIterator<const_iterator> const_reverse_iterator;
 
   FLATBUFFERS_CONSTEXPR uint16_t size() const { return length; }
 
   return_type Get(uoffset_t i) const {
     FLATBUFFERS_ASSERT(i < size());
-    return IndirectHelper<T>::Read(Data(), i);
+    return IndirectHelper<IndirectHelperType>::Read(Data(), i);
   }
 
   return_type operator[](uoffset_t i) const { return Get(i); }
 
+  // If this is a Vector of enums, T will be its storage type, not the enum
+  // type. This function makes it convenient to retrieve value with enum
+  // type E.
+  template<typename E> E GetEnum(uoffset_t i) const {
+    return static_cast<E>(Get(i));
+  }
+
   const_iterator begin() const { return const_iterator(Data(), 0); }
   const_iterator end() const { return const_iterator(Data(), size()); }
 
@@ -432,22 +470,20 @@
   const_reverse_iterator crbegin() const { return rbegin(); }
   const_reverse_iterator crend() const { return rend(); }
 
-  // Change elements if you have a non-const pointer to this object.
-  void Mutate(uoffset_t i, const T &val) {
-    FLATBUFFERS_ASSERT(i < size());
-    WriteScalar(data() + i, val);
-  }
-
   // Get a mutable pointer to elements inside this array.
-  // @note This method should be only used to mutate arrays of structs followed
-  //  by a @p Mutate operation. For primitive types use @p Mutate directly.
+  // This method used to mutate arrays of structs followed by a @p Mutate
+  // operation. For primitive types use @p Mutate directly.
   // @warning Assignments and reads to/from the dereferenced pointer are not
   //  automatically converted to the correct endianness.
-  T *GetMutablePointer(uoffset_t i) const {
+  typename flatbuffers::conditional<scalar_tag::value, void, T *>::type
+  GetMutablePointer(uoffset_t i) const {
     FLATBUFFERS_ASSERT(i < size());
     return const_cast<T *>(&data()[i]);
   }
 
+  // Change elements if you have a non-const pointer to this object.
+  void Mutate(uoffset_t i, const T &val) { MutateImpl(scalar_tag(), i, val); }
+
   // The raw data in little endian format. Use with care.
   const uint8_t *Data() const { return data_; }
 
@@ -457,7 +493,48 @@
   const T *data() const { return reinterpret_cast<const T *>(Data()); }
   T *data() { return reinterpret_cast<T *>(Data()); }
 
+  // Copy data from a span with endian conversion.
+  // If this Array and the span overlap, the behavior is undefined.
+  void CopyFromSpan(flatbuffers::span<const T, length> src) {
+    const auto p1 = reinterpret_cast<const uint8_t *>(src.data());
+    const auto p2 = Data();
+    FLATBUFFERS_ASSERT(!(p1 >= p2 && p1 < (p2 + length)) &&
+                       !(p2 >= p1 && p2 < (p1 + length)));
+    (void)p1;
+    (void)p2;
+
+    CopyFromSpanImpl(
+        flatbuffers::integral_constant<bool,
+        !scalar_tag::value || sizeof(T) == 1 || FLATBUFFERS_LITTLEENDIAN>(),
+        src);
+  }
+
  protected:
+  void MutateImpl(flatbuffers::integral_constant<bool, true>, uoffset_t i,
+                  const T &val) {
+    FLATBUFFERS_ASSERT(i < size());
+    WriteScalar(data() + i, val);
+  }
+
+  void MutateImpl(flatbuffers::integral_constant<bool, false>, uoffset_t i,
+                  const T &val) {
+    *(GetMutablePointer(i)) = val;
+  }
+
+  void CopyFromSpanImpl(flatbuffers::integral_constant<bool, true>,
+                        flatbuffers::span<const T, length> src) {
+    // Use std::memcpy() instead of std::copy() to avoid preformance degradation
+    // due to aliasing if T is char or unsigned char.
+    // The size is known at compile time, so memcpy would be inlined.
+    std::memcpy(data(), src.data(), length * sizeof(T));
+  }
+
+  // Copy data from flatbuffers::span with endian conversion.
+  void CopyFromSpanImpl(flatbuffers::integral_constant<bool, false>,
+                        flatbuffers::span<const T, length> src) {
+    for (size_type k = 0; k < length; k++) { Mutate(k, src[k]); }
+  }
+
   // This class is only used to access pre-existing data. Don't ever
   // try to construct these manually.
   // 'constexpr' allows us to use 'size()' at compile time.
@@ -475,8 +552,58 @@
   // This class is a pointer. Copying will therefore create an invalid object.
   // Private and unimplemented copy constructor.
   Array(const Array &);
+  Array &operator=(const Array &);
 };
 
+// Specialization for Array[struct] with access using Offset<void> pointer.
+// This specialization used by idl_gen_text.cpp.
+template<typename T, uint16_t length> class Array<Offset<T>, length> {
+  static_assert(flatbuffers::is_same<T, void>::value, "unexpected type T");
+
+ public:
+  typedef const void *return_type;
+
+  const uint8_t *Data() const { return data_; }
+
+  // Make idl_gen_text.cpp::PrintContainer happy.
+  return_type operator[](uoffset_t) const {
+    FLATBUFFERS_ASSERT(false);
+    return nullptr;
+  }
+
+ private:
+  // This class is only used to access pre-existing data.
+  Array();
+  Array(const Array &);
+  Array &operator=(const Array &);
+
+  uint8_t data_[1];
+};
+
+// Cast a raw T[length] to a raw flatbuffers::Array<T, length>
+// without endian conversion. Use with care.
+template<typename T, uint16_t length>
+Array<T, length>& CastToArray(T (&arr)[length]) {
+  return *reinterpret_cast<Array<T, length> *>(arr);
+}
+
+template<typename T, uint16_t length>
+const Array<T, length>& CastToArray(const T (&arr)[length]) {
+  return *reinterpret_cast<const Array<T, length> *>(arr);
+}
+
+template<typename E, typename T, uint16_t length>
+Array<E, length> &CastToArrayOfEnum(T (&arr)[length]) {
+  static_assert(sizeof(E) == sizeof(T), "invalid enum type E");
+  return *reinterpret_cast<Array<E, length> *>(arr);
+}
+
+template<typename E, typename T, uint16_t length>
+const Array<E, length> &CastToArrayOfEnum(const T (&arr)[length]) {
+  static_assert(sizeof(E) == sizeof(T), "invalid enum type E");
+  return *reinterpret_cast<const Array<E, length> *>(arr);
+}
+
 // Lexicographically compare two strings (possibly containing nulls), and
 // return true if the first is less than the second.
 static inline bool StringLessThan(const char *a_data, uoffset_t a_size,
@@ -504,16 +631,24 @@
 
 // Convenience function to get std::string from a String returning an empty
 // string on null pointer.
-static inline std::string GetString(const String * str) {
+static inline std::string GetString(const String *str) {
   return str ? str->str() : "";
 }
 
 // Convenience function to get char* from a String returning an empty string on
 // null pointer.
-static inline const char * GetCstring(const String * str) {
+static inline const char *GetCstring(const String *str) {
   return str ? str->c_str() : "";
 }
 
+#ifdef FLATBUFFERS_HAS_STRING_VIEW
+// Convenience function to get string_view from a String returning an empty
+// string_view on null pointer.
+static inline flatbuffers::string_view GetStringView(const String *str) {
+  return str ? str->string_view() : flatbuffers::string_view();
+}
+#endif // FLATBUFFERS_HAS_STRING_VIEW
+
 // Allocator interface. This is flatbuffers-specific and meant only for
 // `vector_downward` usage.
 class Allocator {
@@ -547,9 +682,9 @@
   // to `new_p` of `new_size`. Only memory of size `in_use_front` and
   // `in_use_back` will be copied from the front and back of the old memory
   // allocation.
-  void memcpy_downward(uint8_t *old_p, size_t old_size,
-                       uint8_t *new_p, size_t new_size,
-                       size_t in_use_back, size_t in_use_front) {
+  void memcpy_downward(uint8_t *old_p, size_t old_size, uint8_t *new_p,
+                       size_t new_size, size_t in_use_back,
+                       size_t in_use_front) {
     memcpy(new_p + new_size - in_use_back, old_p + old_size - in_use_back,
            in_use_back);
     memcpy(new_p, old_p, in_use_front);
@@ -563,13 +698,9 @@
     return new uint8_t[size];
   }
 
-  void deallocate(uint8_t *p, size_t) FLATBUFFERS_OVERRIDE {
-    delete[] p;
-  }
+  void deallocate(uint8_t *p, size_t) FLATBUFFERS_OVERRIDE { delete[] p; }
 
-  static void dealloc(void *p, size_t) {
-    delete[] static_cast<uint8_t *>(p);
-  }
+  static void dealloc(void *p, size_t) { delete[] static_cast<uint8_t *>(p); }
 };
 
 // These functions allow for a null allocator to mean use the default allocator,
@@ -582,18 +713,19 @@
 }
 
 inline void Deallocate(Allocator *allocator, uint8_t *p, size_t size) {
-  if (allocator) allocator->deallocate(p, size);
-  else DefaultAllocator().deallocate(p, size);
+  if (allocator)
+    allocator->deallocate(p, size);
+  else
+    DefaultAllocator().deallocate(p, size);
 }
 
 inline uint8_t *ReallocateDownward(Allocator *allocator, uint8_t *old_p,
                                    size_t old_size, size_t new_size,
                                    size_t in_use_back, size_t in_use_front) {
-  return allocator
-      ? allocator->reallocate_downward(old_p, old_size, new_size,
-                                       in_use_back, in_use_front)
-      : DefaultAllocator().reallocate_downward(old_p, old_size, new_size,
-                                               in_use_back, in_use_front);
+  return allocator ? allocator->reallocate_downward(old_p, old_size, new_size,
+                                                    in_use_back, in_use_front)
+                   : DefaultAllocator().reallocate_downward(
+                         old_p, old_size, new_size, in_use_back, in_use_front);
 }
 
 // DetachedBuffer is a finished flatbuffer memory region, detached from its
@@ -638,6 +770,8 @@
   #if !defined(FLATBUFFERS_CPP98_STL)
   // clang-format on
   DetachedBuffer &operator=(DetachedBuffer &&other) {
+    if (this == &other) return *this;
+
     destroy();
 
     allocator_ = other.allocator_;
@@ -694,7 +828,7 @@
   #endif  // !defined(FLATBUFFERS_CPP98_STL)
   // clang-format on
 
-protected:
+ protected:
   Allocator *allocator_;
   bool own_allocator_;
   uint8_t *buf_;
@@ -726,10 +860,8 @@
 // Essentially, this supports 2 std::vectors in a single buffer.
 class vector_downward {
  public:
-  explicit vector_downward(size_t initial_size,
-                           Allocator *allocator,
-                           bool own_allocator,
-                           size_t buffer_minalign)
+  explicit vector_downward(size_t initial_size, Allocator *allocator,
+                           bool own_allocator, size_t buffer_minalign)
       : allocator_(allocator),
         own_allocator_(own_allocator),
         initial_size_(initial_size),
@@ -745,15 +877,15 @@
   #else
   vector_downward(vector_downward &other)
   #endif  // defined(FLATBUFFERS_CPP98_STL)
-  // clang-format on
-    : allocator_(other.allocator_),
-      own_allocator_(other.own_allocator_),
-      initial_size_(other.initial_size_),
-      buffer_minalign_(other.buffer_minalign_),
-      reserved_(other.reserved_),
-      buf_(other.buf_),
-      cur_(other.cur_),
-      scratch_(other.scratch_) {
+      // clang-format on
+      : allocator_(other.allocator_),
+        own_allocator_(other.own_allocator_),
+        initial_size_(other.initial_size_),
+        buffer_minalign_(other.buffer_minalign_),
+        reserved_(other.reserved_),
+        buf_(other.buf_),
+        cur_(other.cur_),
+        scratch_(other.scratch_) {
     // No change in other.allocator_
     // No change in other.initial_size_
     // No change in other.buffer_minalign_
@@ -797,9 +929,7 @@
     clear_scratch();
   }
 
-  void clear_scratch() {
-    scratch_ = buf_;
-  }
+  void clear_scratch() { scratch_ = buf_; }
 
   void clear_allocator() {
     if (own_allocator_ && allocator_) { delete allocator_; }
@@ -858,7 +988,7 @@
   Allocator *get_custom_allocator() { return allocator_; }
 
   uoffset_t size() const {
-    return static_cast<uoffset_t>(reserved_ - (cur_ - buf_));
+    return static_cast<uoffset_t>(reserved_ - static_cast<size_t>(cur_ - buf_));
   }
 
   uoffset_t scratch_size() const {
@@ -952,8 +1082,8 @@
     auto old_reserved = reserved_;
     auto old_size = size();
     auto old_scratch_size = scratch_size();
-    reserved_ += (std::max)(len,
-                            old_reserved ? old_reserved / 2 : initial_size_);
+    reserved_ +=
+        (std::max)(len, old_reserved ? old_reserved / 2 : initial_size_);
     reserved_ = (reserved_ + buffer_minalign_ - 1) & ~(buffer_minalign_ - 1);
     if (buf_) {
       buf_ = ReallocateDownward(allocator_, buf_, old_reserved, reserved_,
@@ -978,13 +1108,13 @@
   // Eventually the returned pointer gets passed down to memcpy, so
   // we need it to be non-null to avoid undefined behavior.
   static uint8_t t;
-  return v.empty() ? reinterpret_cast<const T*>(&t) : &v.front();
+  return v.empty() ? reinterpret_cast<const T *>(&t) : &v.front();
 }
 template<typename T, typename Alloc> T *data(std::vector<T, Alloc> &v) {
   // Eventually the returned pointer gets passed down to memcpy, so
   // we need it to be non-null to avoid undefined behavior.
   static uint8_t t;
-  return v.empty() ? reinterpret_cast<T*>(&t) : &v.front();
+  return v.empty() ? reinterpret_cast<T *>(&t) : &v.front();
 }
 
 /// @endcond
@@ -1011,11 +1141,10 @@
   /// minimum alignment upon reallocation. Only needed if you intend to store
   /// types with custom alignment AND you wish to read the buffer in-place
   /// directly after creation.
-  explicit FlatBufferBuilder(size_t initial_size = 1024,
-                             Allocator *allocator = nullptr,
-                             bool own_allocator = false,
-                             size_t buffer_minalign =
-                                 AlignOf<largest_scalar_t>())
+  explicit FlatBufferBuilder(
+      size_t initial_size = 1024, Allocator *allocator = nullptr,
+      bool own_allocator = false,
+      size_t buffer_minalign = AlignOf<largest_scalar_t>())
       : buf_(initial_size, allocator, own_allocator, buffer_minalign),
         num_field_loc(0),
         max_voffset_(0),
@@ -1110,6 +1239,14 @@
     return buf_.data();
   }
 
+  /// @brief Get the serialized buffer (after you call `Finish()`) as a span.
+  /// @return Returns a constructed flatbuffers::span that is a view over the 
+  /// FlatBuffer data inside the buffer.
+  flatbuffers::span<uint8_t> GetBufferSpan() const {
+    Finished();
+    return flatbuffers::span<uint8_t>(buf_.data(), buf_.size());
+  }
+
   /// @brief Get a pointer to an unfinished buffer.
   /// @return Returns a `uint8_t` pointer to the unfinished buffer.
   uint8_t *GetCurrentBufferPointer() const { return buf_.data(); }
@@ -1118,8 +1255,8 @@
   /// @warning Do NOT attempt to use this FlatBufferBuilder afterwards!
   /// @return A `FlatBuffer` that owns the buffer and its allocator and
   /// behaves similar to a `unique_ptr` with a deleter.
-  FLATBUFFERS_ATTRIBUTE(deprecated("use Release() instead")) DetachedBuffer
-  ReleaseBufferPointer() {
+  FLATBUFFERS_ATTRIBUTE(deprecated("use Release() instead"))
+  DetachedBuffer ReleaseBufferPointer() {
     Finished();
     return buf_.release();
   }
@@ -1132,13 +1269,14 @@
   }
 
   /// @brief Get the released pointer to the serialized buffer.
-  /// @param The size of the memory block containing
+  /// @param size The size of the memory block containing
   /// the serialized `FlatBuffer`.
-  /// @param The offset from the released pointer where the finished
+  /// @param offset The offset from the released pointer where the finished
   /// `FlatBuffer` starts.
   /// @return A raw pointer to the start of the memory block containing
   /// the serialized `FlatBuffer`.
-  /// @remark If the allocator is owned, it gets deleted when the destructor is called..
+  /// @remark If the allocator is owned, it gets deleted when the destructor is
+  /// called..
   uint8_t *ReleaseRaw(size_t &size, size_t &offset) {
     Finished();
     return buf_.release_raw(size, offset);
@@ -1149,7 +1287,7 @@
   /// you call Finish()). You can use this information if you need to embed
   /// a FlatBuffer in some other buffer, such that you can later read it
   /// without first having to copy it into its own buffer.
-  size_t GetBufferMinAlignment() {
+  size_t GetBufferMinAlignment() const {
     Finished();
     return minalign_;
   }
@@ -1167,12 +1305,13 @@
 
   /// @brief In order to save space, fields that are set to their default value
   /// don't get serialized into the buffer.
-  /// @param[in] bool fd When set to `true`, always serializes default values that are set.
-  /// Optional fields which are not set explicitly, will still not be serialized.
+  /// @param[in] fd When set to `true`, always serializes default values that
+  /// are set. Optional fields which are not set explicitly, will still not be
+  /// serialized.
   void ForceDefaults(bool fd) { force_defaults_ = fd; }
 
   /// @brief By default vtables are deduped in order to save space.
-  /// @param[in] bool dedup When set to `true`, dedup vtables.
+  /// @param[in] dedup When set to `true`, dedup vtables.
   void DedupVtables(bool dedup) { dedup_vtables_ = dedup; }
 
   /// @cond FLATBUFFERS_INTERNAL
@@ -1232,6 +1371,11 @@
     TrackField(field, off);
   }
 
+  template<typename T> void AddElement(voffset_t field, T e) {
+    auto off = PushElement(e);
+    TrackField(field, off);
+  }
+
   template<typename T> void AddOffset(voffset_t field, Offset<T> off) {
     if (off.IsNull()) return;  // Don't store.
     AddElement(field, ReferTo(off.o), static_cast<uoffset_t>(0));
@@ -1326,7 +1470,7 @@
            it += sizeof(uoffset_t)) {
         auto vt_offset_ptr = reinterpret_cast<uoffset_t *>(it);
         auto vt2 = reinterpret_cast<voffset_t *>(buf_.data_at(*vt_offset_ptr));
-        auto vt2_size = *vt2;
+        auto vt2_size = ReadScalar<voffset_t>(vt2);
         if (vt1_size != vt2_size || 0 != memcmp(vt2, vt1, vt1_size)) continue;
         vt_use = *vt_offset_ptr;
         buf_.pop(GetSize() - vtableoffsetloc);
@@ -1536,6 +1680,9 @@
     // causing the wrong overload to be selected, remove it.
     AssertScalarT<T>();
     StartVector(len, sizeof(T));
+    if (len == 0) {
+      return Offset<Vector<T>>(EndVector(len));
+    }
     // clang-format off
     #if FLATBUFFERS_LITTLEENDIAN
       PushBytes(reinterpret_cast<const uint8_t *>(v), len * sizeof(T));
@@ -1655,14 +1802,14 @@
     extern T Pack(const S &);
     std::vector<T> vv(len);
     std::transform(v, v + len, vv.begin(), Pack);
-    return CreateVectorOfStructs<T>(vv.data(), vv.size());
+    return CreateVectorOfStructs<T>(data(vv), vv.size());
   }
 
   // clang-format off
   #ifndef FLATBUFFERS_CPP98_STL
   /// @brief Serialize an array of structs into a FlatBuffer `vector`.
   /// @tparam T The data type of the struct array elements.
-  /// @param[in] f A function that takes the current iteration 0..vector_size-1
+  /// @param[in] filler A function that takes the current iteration 0..vector_size-1
   /// and a pointer to the struct that must be filled.
   /// @return Returns a typed `Offset` into the serialized data indicating
   /// where the vector is stored.
@@ -1702,7 +1849,7 @@
 
   /// @brief Serialize a `std::vector` of structs into a FlatBuffer `vector`.
   /// @tparam T The data type of the `std::vector` struct elements.
-  /// @param[in]] v A const reference to the `std::vector` of structs to
+  /// @param[in] v A const reference to the `std::vector` of structs to
   /// serialize into the buffer as a `vector`.
   /// @return Returns a typed `Offset` into the serialized data indicating
   /// where the vector is stored.
@@ -1716,7 +1863,7 @@
   /// `vector`.
   /// @tparam T The data type of the `std::vector` struct elements.
   /// @tparam S The data type of the `std::vector` native struct elements.
-  /// @param[in]] v A const reference to the `std::vector` of structs to
+  /// @param[in] v A const reference to the `std::vector` of structs to
   /// serialize into the buffer as a `vector`.
   /// @return Returns a typed `Offset` into the serialized data indicating
   /// where the vector is stored.
@@ -1732,15 +1879,15 @@
       return a.KeyCompareLessThan(&b);
     }
 
-   private:
-    StructKeyComparator &operator=(const StructKeyComparator &);
+    FLATBUFFERS_DELETE_FUNC(
+        StructKeyComparator &operator=(const StructKeyComparator &))
   };
   /// @endcond
 
   /// @brief Serialize a `std::vector` of structs into a FlatBuffer `vector`
   /// in sorted order.
   /// @tparam T The data type of the `std::vector` struct elements.
-  /// @param[in]] v A const reference to the `std::vector` of structs to
+  /// @param[in] v A const reference to the `std::vector` of structs to
   /// serialize into the buffer as a `vector`.
   /// @return Returns a typed `Offset` into the serialized data indicating
   /// where the vector is stored.
@@ -1753,7 +1900,7 @@
   /// `vector` in sorted order.
   /// @tparam T The data type of the `std::vector` struct elements.
   /// @tparam S The data type of the `std::vector` native struct elements.
-  /// @param[in]] v A const reference to the `std::vector` of structs to
+  /// @param[in] v A const reference to the `std::vector` of structs to
   /// serialize into the buffer as a `vector`.
   /// @return Returns a typed `Offset` into the serialized data indicating
   /// where the vector is stored.
@@ -1792,13 +1939,14 @@
     extern T Pack(const S &);
     typedef T (*Pack_t)(const S &);
     std::vector<T> vv(len);
-    std::transform(v, v + len, vv.begin(), static_cast<Pack_t&>(Pack));
+    std::transform(v, v + len, vv.begin(), static_cast<Pack_t &>(Pack));
     return CreateVectorOfSortedStructs<T>(vv, len);
   }
 
   /// @cond FLATBUFFERS_INTERNAL
   template<typename T> struct TableKeyComparator {
     TableKeyComparator(vector_downward &buf) : buf_(buf) {}
+    TableKeyComparator(const TableKeyComparator &other) : buf_(other.buf_) {}
     bool operator()(const Offset<T> &a, const Offset<T> &b) const {
       auto table_a = reinterpret_cast<T *>(buf_.data_at(a.o));
       auto table_b = reinterpret_cast<T *>(buf_.data_at(b.o));
@@ -1807,7 +1955,7 @@
     vector_downward &buf_;
 
    private:
-    TableKeyComparator &operator=(const TableKeyComparator &);
+    FLATBUFFERS_DELETE_FUNC(TableKeyComparator &operator=(const TableKeyComparator &other))
   };
   /// @endcond
 
@@ -1873,12 +2021,12 @@
   }
 
   template<typename T>
-  Offset<Vector<const T*>> CreateUninitializedVectorOfStructs(size_t len, T **buf) {
+  Offset<Vector<const T *>> CreateUninitializedVectorOfStructs(size_t len,
+                                                               T **buf) {
     return CreateUninitializedVector(len, sizeof(T),
                                      reinterpret_cast<uint8_t **>(buf));
   }
 
-
   // @brief Create a vector of scalar type T given as input a vector of scalar
   // type U, useful with e.g. pre "enum class" enums, or any existing scalar
   // data of the wrong type.
@@ -1927,8 +2075,7 @@
     buf_.swap_allocator(other.buf_);
   }
 
-protected:
-
+ protected:
   // You shouldn't really be copying instances of this class.
   FlatBufferBuilder(const FlatBufferBuilder &);
   FlatBufferBuilder &operator=(const FlatBufferBuilder &);
@@ -1981,8 +2128,8 @@
     bool operator()(const Offset<String> &a, const Offset<String> &b) const {
       auto stra = reinterpret_cast<const String *>(buf_->data_at(a.o));
       auto strb = reinterpret_cast<const String *>(buf_->data_at(b.o));
-      return StringLessThan(stra->data(), stra->size(),
-                            strb->data(), strb->size());
+      return StringLessThan(stra->data(), stra->size(), strb->data(),
+                            strb->size());
     }
     const vector_downward *buf_;
   };
@@ -2046,13 +2193,15 @@
 /// This function is UNDEFINED for FlatBuffers whose schema does not include
 /// a file_identifier (likely points at padding or the start of a the root
 /// vtable).
-inline const char *GetBufferIdentifier(const void *buf, bool size_prefixed = false) {
+inline const char *GetBufferIdentifier(const void *buf,
+                                       bool size_prefixed = false) {
   return reinterpret_cast<const char *>(buf) +
          ((size_prefixed) ? 2 * sizeof(uoffset_t) : sizeof(uoffset_t));
 }
 
 // Helper to see if the identifier in a buffer has the expected value.
-inline bool BufferHasIdentifier(const void *buf, const char *identifier, bool size_prefixed = false) {
+inline bool BufferHasIdentifier(const void *buf, const char *identifier,
+                                bool size_prefixed = false) {
   return strncmp(GetBufferIdentifier(buf, size_prefixed), identifier,
                  FlatBufferBuilder::kFileIdentifierLength) == 0;
 }
@@ -2069,8 +2218,7 @@
         num_tables_(0),
         max_tables_(_max_tables),
         upper_bound_(0),
-        check_alignment_(_check_alignment)
-  {
+        check_alignment_(_check_alignment) {
     FLATBUFFERS_ASSERT(size_ < FLATBUFFERS_MAX_BUFFER_SIZE);
   }
 
@@ -2101,7 +2249,7 @@
   }
 
   template<typename T> bool VerifyAlignment(size_t elem) const {
-    return (elem & (sizeof(T) - 1)) == 0 || !check_alignment_;
+    return Check((elem & (sizeof(T) - 1)) == 0 || !check_alignment_);
   }
 
   // Verify a range indicated by sizeof(T).
@@ -2109,13 +2257,18 @@
     return VerifyAlignment<T>(elem) && Verify(elem, sizeof(T));
   }
 
+  bool VerifyFromPointer(const uint8_t *p, size_t len) {
+    auto o = static_cast<size_t>(p - buf_);
+    return Verify(o, len);
+  }
+
   // Verify relative to a known-good base pointer.
   bool Verify(const uint8_t *base, voffset_t elem_off, size_t elem_len) const {
     return Verify(static_cast<size_t>(base - buf_) + elem_off, elem_len);
   }
 
-  template<typename T> bool Verify(const uint8_t *base, voffset_t elem_off)
-      const {
+  template<typename T>
+  bool Verify(const uint8_t *base, voffset_t elem_off) const {
     return Verify(static_cast<size_t>(base - buf_) + elem_off, sizeof(T));
   }
 
@@ -2138,16 +2291,15 @@
   // Verify a pointer (may be NULL) to string.
   bool VerifyString(const String *str) const {
     size_t end;
-    return !str ||
-           (VerifyVectorOrString(reinterpret_cast<const uint8_t *>(str),
-                                 1, &end) &&
-            Verify(end, 1) &&      // Must have terminator
-            Check(buf_[end] == '\0'));  // Terminating byte must be 0.
+    return !str || (VerifyVectorOrString(reinterpret_cast<const uint8_t *>(str),
+                                         1, &end) &&
+                    Verify(end, 1) &&           // Must have terminator
+                    Check(buf_[end] == '\0'));  // Terminating byte must be 0.
   }
 
   // Common code between vectors and strings.
   bool VerifyVectorOrString(const uint8_t *vec, size_t elem_size,
-                    size_t *end = nullptr) const {
+                            size_t *end = nullptr) const {
     auto veco = static_cast<size_t>(vec - buf_);
     // Check we can read the size field.
     if (!Verify<uoffset_t>(veco)) return false;
@@ -2182,11 +2334,12 @@
     return true;
   }
 
-  bool VerifyTableStart(const uint8_t *table) {
+  __supress_ubsan__("unsigned-integer-overflow") bool VerifyTableStart(
+      const uint8_t *table) {
     // Check the vtable offset.
     auto tableo = static_cast<size_t>(table - buf_);
     if (!Verify<soffset_t>(tableo)) return false;
-    // This offset may be signed, but doing the substraction unsigned always
+    // This offset may be signed, but doing the subtraction unsigned always
     // gives the result we want.
     auto vtableo = tableo - static_cast<size_t>(ReadScalar<soffset_t>(table));
     // Check the vtable size field, then check vtable fits in its entirety.
@@ -2197,9 +2350,8 @@
 
   template<typename T>
   bool VerifyBufferFromStart(const char *identifier, size_t start) {
-    if (identifier &&
-        (size_ < 2 * sizeof(flatbuffers::uoffset_t) ||
-         !BufferHasIdentifier(buf_ + start, identifier))) {
+    if (identifier && !Check((size_ >= 2 * sizeof(flatbuffers::uoffset_t) &&
+                              BufferHasIdentifier(buf_ + start, identifier)))) {
       return false;
     }
 
@@ -2331,6 +2483,12 @@
   uint8_t *GetAddressOf(uoffset_t o) { return &data_[o]; }
 
  private:
+  // private constructor & copy constructor: you obtain instances of this
+  // class by pointing to existing data only
+  Struct();
+  Struct(const Struct &);
+  Struct &operator=(const Struct &);
+
   uint8_t data_[1];
 };
 
@@ -2375,12 +2533,26 @@
     return field_offset ? reinterpret_cast<P>(p) : nullptr;
   }
 
+  template<typename Raw, typename Face>
+  flatbuffers::Optional<Face> GetOptional(voffset_t field) const {
+    auto field_offset = GetOptionalFieldOffset(field);
+    auto p = data_ + field_offset;
+    return field_offset ? Optional<Face>(static_cast<Face>(ReadScalar<Raw>(p)))
+                        : Optional<Face>();
+  }
+
   template<typename T> bool SetField(voffset_t field, T val, T def) {
     auto field_offset = GetOptionalFieldOffset(field);
     if (!field_offset) return IsTheSameAs(val, def);
     WriteScalar(data_ + field_offset, val);
     return true;
   }
+  template<typename T> bool SetField(voffset_t field, T val) {
+    auto field_offset = GetOptionalFieldOffset(field);
+    if (!field_offset) return false;
+    WriteScalar(data_ + field_offset, val);
+    return true;
+  }
 
   bool SetPointer(voffset_t field, const uint8_t *val) {
     auto field_offset = GetOptionalFieldOffset(field);
@@ -2443,12 +2615,24 @@
   // class by pointing to existing data only
   Table();
   Table(const Table &other);
+  Table &operator=(const Table &);
 
   uint8_t data_[1];
 };
 
-template<typename T> void FlatBufferBuilder::Required(Offset<T> table,
-                                                      voffset_t field) {
+// This specialization allows avoiding warnings like:
+// MSVC C4800: type: forcing value to bool 'true' or 'false'.
+template<>
+inline flatbuffers::Optional<bool> Table::GetOptional<uint8_t, bool>(
+    voffset_t field) const {
+  auto field_offset = GetOptionalFieldOffset(field);
+  auto p = data_ + field_offset;
+  return field_offset ? Optional<bool>(ReadScalar<uint8_t>(p) != 0)
+                      : Optional<bool>();
+}
+
+template<typename T>
+void FlatBufferBuilder::Required(Offset<T> table, voffset_t field) {
   auto table_ptr = reinterpret_cast<const Table *>(buf_.data_at(table.o));
   bool ok = table_ptr->GetOptionalFieldOffset(field) != 0;
   // If this fails, the caller will show what field needs to be set.
@@ -2495,7 +2679,9 @@
 }
 
 /// @brief This return the prefixed size of a FlatBuffer.
-inline uoffset_t GetPrefixedSize(const uint8_t* buf){ return ReadScalar<uoffset_t>(buf); }
+inline uoffset_t GetPrefixedSize(const uint8_t *buf) {
+  return ReadScalar<uoffset_t>(buf);
+}
 
 // Base class for native objects (FlatBuffer data de-serialized into native
 // C++ data structures).
@@ -2622,10 +2808,13 @@
 // clang-format on
 
 // Basic type info cost just 16bits per field!
+// We're explicitly defining the signedness since the signedness of integer
+// bitfields is otherwise implementation-defined and causes warnings on older
+// GCC compilers.
 struct TypeCode {
-  uint16_t base_type : 4;  // ElementaryType
-  uint16_t is_vector : 1;
-  int16_t sequence_ref : 11;  // Index into type_refs below, or -1 for none.
+  unsigned short base_type : 4;  // ElementaryType
+  unsigned short is_repeating : 1;  // Either vector (in table) or array (in struct)
+  signed short sequence_ref : 11;  // Index into type_refs below, or -1 for none.
 };
 
 static_assert(sizeof(TypeCode) == 2, "TypeCode");
@@ -2638,10 +2827,11 @@
 struct TypeTable {
   SequenceType st;
   size_t num_elems;  // of type_codes, values, names (but not type_refs).
-  const TypeCode *type_codes;  // num_elems count
+  const TypeCode *type_codes;     // num_elems count
   const TypeFunction *type_refs;  // less than num_elems entries (see TypeCode).
+  const int16_t *array_sizes;     // less than num_elems entries (see TypeCode).
   const int64_t *values;  // Only set for non-consecutive enum/union or structs.
-  const char * const *names;     // Only set if compiled with --reflect-names.
+  const char *const *names;  // Only set if compiled with --reflect-names.
 };
 
 // String which identifies the current version of FlatBuffers.
diff --git a/include/flatbuffers/flatc.h b/include/flatbuffers/flatc.h
index f2765d2..5e2709e 100644
--- a/include/flatbuffers/flatc.h
+++ b/include/flatbuffers/flatc.h
@@ -14,18 +14,22 @@
  * limitations under the License.
  */
 
+#ifndef FLATBUFFERS_FLATC_H_
+#define FLATBUFFERS_FLATC_H_
+
 #include <functional>
 #include <limits>
 #include <string>
+
 #include "flatbuffers/flatbuffers.h"
 #include "flatbuffers/idl.h"
 #include "flatbuffers/util.h"
 
-#ifndef FLATC_H_
-#  define FLATC_H_
-
 namespace flatbuffers {
 
+extern void LogCompilerWarn(const std::string &warn);
+extern void LogCompilerError(const std::string &err);
+
 class FlatCompiler {
  public:
   // Output generator for the various programming languages and formats we
@@ -93,4 +97,4 @@
 
 }  // namespace flatbuffers
 
-#endif  // FLATC_H_
+#endif  // FLATBUFFERS_FLATC_H_
diff --git a/include/flatbuffers/flexbuffers.h b/include/flatbuffers/flexbuffers.h
index 7cba5b7..a45d14b 100644
--- a/include/flatbuffers/flexbuffers.h
+++ b/include/flatbuffers/flexbuffers.h
@@ -65,7 +65,9 @@
   FBT_VECTOR_UINT = 12,
   FBT_VECTOR_FLOAT = 13,
   FBT_VECTOR_KEY = 14,
-  FBT_VECTOR_STRING = 15,
+  // DEPRECATED, use FBT_VECTOR or FBT_VECTOR_KEY instead.
+  // Read test.cpp/FlexBuffersDeprecatedTest() for details on why.
+  FBT_VECTOR_STRING_DEPRECATED = 15,
   FBT_VECTOR_INT2 = 16,  // Typed tuple (no type table, no size field).
   FBT_VECTOR_UINT2 = 17,
   FBT_VECTOR_FLOAT2 = 18,
@@ -88,7 +90,7 @@
 }
 
 inline bool IsTypedVector(Type t) {
-  return (t >= FBT_VECTOR_INT && t <= FBT_VECTOR_STRING) ||
+  return (t >= FBT_VECTOR_INT && t <= FBT_VECTOR_STRING_DEPRECATED) ||
          t == FBT_VECTOR_BOOL;
 }
 
@@ -212,26 +214,40 @@
   uint8_t byte_width_;
 };
 
-// Stores size in `byte_width_` bytes before data_ pointer.
+// Object that has a size, obtained either from size prefix, or elsewhere.
 class Sized : public Object {
  public:
-  Sized(const uint8_t *data, uint8_t byte_width) : Object(data, byte_width) {}
-  size_t size() const {
+  // Size prefix.
+  Sized(const uint8_t *data, uint8_t byte_width)
+      : Object(data, byte_width), size_(read_size()) {}
+  // Manual size.
+  Sized(const uint8_t *data, uint8_t byte_width, size_t sz)
+      : Object(data, byte_width), size_(sz) {}
+  size_t size() const { return size_; }
+  // Access size stored in `byte_width_` bytes before data_ pointer.
+  size_t read_size() const {
     return static_cast<size_t>(ReadUInt64(data_ - byte_width_, byte_width_));
   }
+
+ protected:
+  size_t size_;
 };
 
 class String : public Sized {
  public:
+  // Size prefix.
   String(const uint8_t *data, uint8_t byte_width) : Sized(data, byte_width) {}
+  // Manual size.
+  String(const uint8_t *data, uint8_t byte_width, size_t sz)
+      : Sized(data, byte_width, sz) {}
 
   size_t length() const { return size(); }
   const char *c_str() const { return reinterpret_cast<const char *>(data_); }
-  std::string str() const { return std::string(c_str(), length()); }
+  std::string str() const { return std::string(c_str(), size()); }
 
   static String EmptyString() {
-    static const uint8_t empty_string[] = { 0 /*len*/, 0 /*terminator*/ };
-    return String(empty_string + 1, 1);
+    static const char *empty_string = "";
+    return String(reinterpret_cast<const uint8_t *>(empty_string), 1, 0);
   }
   bool IsTheEmptyString() const { return data_ == EmptyString().data_; }
 };
@@ -279,6 +295,8 @@
 
   Type ElementType() { return type_; }
 
+  friend Reference;
+
  private:
   Type type_;
 
@@ -339,16 +357,22 @@
 
 template<typename T>
 void AppendToString(std::string &s, T &&v, bool keys_quoted) {
-    s += "[ ";
-    for (size_t i = 0; i < v.size(); i++) {
-      if (i) s += ", ";
-      v[i].ToString(true, keys_quoted, s);
-    }
-    s += " ]";
+  s += "[ ";
+  for (size_t i = 0; i < v.size(); i++) {
+    if (i) s += ", ";
+    v[i].ToString(true, keys_quoted, s);
+  }
+  s += " ]";
 }
 
 class Reference {
  public:
+  Reference()
+      : data_(nullptr),
+        parent_width_(0),
+        byte_width_(BIT_WIDTH_8),
+        type_(FBT_NULL) {}
+
   Reference(const uint8_t *data, uint8_t parent_width, uint8_t byte_width,
             Type type)
       : data_(data),
@@ -378,15 +402,19 @@
   bool IsString() const { return type_ == FBT_STRING; }
   bool IsKey() const { return type_ == FBT_KEY; }
   bool IsVector() const { return type_ == FBT_VECTOR || type_ == FBT_MAP; }
+  bool IsUntypedVector() const { return type_ == FBT_VECTOR; }
   bool IsTypedVector() const { return flexbuffers::IsTypedVector(type_); }
-  bool IsFixedTypedVector() const { return flexbuffers::IsFixedTypedVector(type_); }
-  bool IsAnyVector() const { return (IsTypedVector() || IsFixedTypedVector() || IsVector());}
+  bool IsFixedTypedVector() const {
+    return flexbuffers::IsFixedTypedVector(type_);
+  }
+  bool IsAnyVector() const {
+    return (IsTypedVector() || IsFixedTypedVector() || IsVector());
+  }
   bool IsMap() const { return type_ == FBT_MAP; }
   bool IsBlob() const { return type_ == FBT_BLOB; }
-
   bool AsBool() const {
     return (type_ == FBT_BOOL ? ReadUInt64(data_, parent_width_)
-                               : AsUInt64()) != 0;
+                              : AsUInt64()) != 0;
   }
 
   // Reads any type as a int64_t. Never fails, does most sensible conversion.
@@ -464,7 +492,11 @@
         case FBT_INDIRECT_UINT:
           return static_cast<double>(ReadUInt64(Indirect(), byte_width_));
         case FBT_NULL: return 0.0;
-        case FBT_STRING: return strtod(AsString().c_str(), nullptr);
+        case FBT_STRING: {
+          double d;
+          flatbuffers::StringToNumber(AsString().c_str(), &d);
+          return d;
+        }
         case FBT_VECTOR: return static_cast<double>(AsVector().size());
         case FBT_BOOL:
           return static_cast<double>(ReadUInt64(data_, parent_width_));
@@ -477,17 +509,22 @@
   float AsFloat() const { return static_cast<float>(AsDouble()); }
 
   const char *AsKey() const {
-    if (type_ == FBT_KEY) {
+    if (type_ == FBT_KEY || type_ == FBT_STRING) {
       return reinterpret_cast<const char *>(Indirect());
     } else {
       return "";
     }
   }
 
-  // This function returns the empty string if you try to read a not-string.
+  // This function returns the empty string if you try to read something that
+  // is not a string or key.
   String AsString() const {
     if (type_ == FBT_STRING) {
       return String(Indirect(), byte_width_);
+    } else if (type_ == FBT_KEY) {
+      auto key = Indirect();
+      return String(key, byte_width_,
+                    strlen(reinterpret_cast<const char *>(key)));
     } else {
       return String::EmptyString();
     }
@@ -549,7 +586,8 @@
       AppendToString<FixedTypedVector>(s, AsFixedTypedVector(), keys_quoted);
     } else if (IsBlob()) {
       auto blob = AsBlob();
-      flatbuffers::EscapeString(reinterpret_cast<const char*>(blob.data()), blob.size(), &s, true, false);
+      flatbuffers::EscapeString(reinterpret_cast<const char *>(blob.data()),
+                                blob.size(), &s, true, false);
     } else {
       s += "(?)";
     }
@@ -577,8 +615,18 @@
 
   TypedVector AsTypedVector() const {
     if (IsTypedVector()) {
-      return TypedVector(Indirect(), byte_width_,
-                         ToTypedVectorElementType(type_));
+      auto tv =
+          TypedVector(Indirect(), byte_width_, ToTypedVectorElementType(type_));
+      if (tv.type_ == FBT_STRING) {
+        // These can't be accessed as strings, since we don't know the bit-width
+        // of the size field, see the declaration of
+        // FBT_VECTOR_STRING_DEPRECATED above for details.
+        // We change the type here to be keys, which are a subtype of strings,
+        // and will ignore the size field. This will truncate strings with
+        // embedded nulls.
+        tv.type_ = FBT_KEY;
+      }
+      return tv;
     } else {
       return TypedVector::EmptyTypedVector();
     }
@@ -723,9 +771,15 @@
 template<> inline int64_t Reference::As<int64_t>() const { return AsInt64(); }
 
 template<> inline uint8_t Reference::As<uint8_t>() const { return AsUInt8(); }
-template<> inline uint16_t Reference::As<uint16_t>() const { return AsUInt16(); }
-template<> inline uint32_t Reference::As<uint32_t>() const { return AsUInt32(); }
-template<> inline uint64_t Reference::As<uint64_t>() const { return AsUInt64(); }
+template<> inline uint16_t Reference::As<uint16_t>() const {
+  return AsUInt16();
+}
+template<> inline uint32_t Reference::As<uint32_t>() const {
+  return AsUInt32();
+}
+template<> inline uint64_t Reference::As<uint64_t>() const {
+  return AsUInt64();
+}
 
 template<> inline double Reference::As<double>() const { return AsDouble(); }
 template<> inline float Reference::As<float>() const { return AsFloat(); }
@@ -1046,7 +1100,7 @@
     for (auto key = start; key < stack_.size(); key += 2) {
       FLATBUFFERS_ASSERT(stack_[key].type_ == FBT_KEY);
     }
-    // Now sort values, so later we can do a binary seach lookup.
+    // Now sort values, so later we can do a binary search lookup.
     // We want to sort 2 array elements at a time.
     struct TwoValue {
       Value key;
@@ -1194,6 +1248,24 @@
     EndMap(start);
   }
 
+  // If you wish to share a value explicitly (a value not shared automatically
+  // through one of the BUILDER_FLAG_SHARE_* flags) you can do so with these
+  // functions. Or if you wish to turn those flags off for performance reasons
+  // and still do some explicit sharing. For example:
+  // builder.IndirectDouble(M_PI);
+  // auto id = builder.LastValue();  // Remember where we stored it.
+  // .. more code goes here ..
+  // builder.ReuseValue(id);  // Refers to same double by offset.
+  // LastValue works regardless of whether the value has a key or not.
+  // Works on any data type.
+  struct Value;
+  Value LastValue() { return stack_.back(); }
+  void ReuseValue(Value v) { stack_.push_back(v); }
+  void ReuseValue(const char *key, Value v) {
+    Key(key);
+    ReuseValue(v);
+  }
+
   // Overloaded Add that tries to call the correct function above.
   void Add(int8_t i) { Int(i); }
   void Add(int16_t i) { Int(i); }
@@ -1319,6 +1391,8 @@
                                                            : FBT_INT);
   }
 
+ public:
+  // This was really intended to be private, except for LastValue/ReuseValue.
   struct Value {
     union {
       int64_t i_;
@@ -1343,7 +1417,10 @@
     Value(uint64_t u, Type t, BitWidth bw)
         : u_(u), type_(t), min_bit_width_(bw) {}
 
-    Value(float f) : f_(f), type_(FBT_FLOAT), min_bit_width_(BIT_WIDTH_32) {}
+    Value(float f)
+        : f_(static_cast<double>(f)),
+          type_(FBT_FLOAT),
+          min_bit_width_(BIT_WIDTH_32) {}
     Value(double f) : f_(f), type_(FBT_FLOAT), min_bit_width_(WidthF(f)) {}
 
     uint8_t StoredPackedType(BitWidth parent_bit_width_ = BIT_WIDTH_8) const {
@@ -1388,6 +1465,7 @@
     }
   };
 
+ private:
   void WriteAny(const Value &val, uint8_t byte_width) {
     switch (val.type_) {
       case FBT_NULL:
@@ -1420,6 +1498,7 @@
     // TODO: instead of asserting, could write vector with larger elements
     // instead, though that would be wasteful.
     FLATBUFFERS_ASSERT(WidthU(len) <= bit_width);
+    Align(bit_width);
     if (!fixed) Write<uint64_t>(len, byte_width);
     auto vloc = buf_.size();
     for (size_t i = 0; i < len; i++) Write(elems[i], byte_width);
@@ -1431,7 +1510,9 @@
 
   Value CreateVector(size_t start, size_t vec_len, size_t step, bool typed,
                      bool fixed, const Value *keys = nullptr) {
-    FLATBUFFERS_ASSERT(!fixed || typed); // typed=false, fixed=true combination is not supported.
+    FLATBUFFERS_ASSERT(
+        !fixed ||
+        typed);  // typed=false, fixed=true combination is not supported.
     // Figure out smallest bit width we can store this vector with.
     auto bit_width = (std::max)(force_min_bit_width_, WidthU(vec_len));
     auto prefix_elems = 1;
@@ -1444,7 +1525,8 @@
     Type vector_type = FBT_KEY;
     // Check bit widths and types for all elements.
     for (size_t i = start; i < stack_.size(); i += step) {
-      auto elem_width = stack_[i].ElemWidth(buf_.size(), i + prefix_elems);
+      auto elem_width =
+          stack_[i].ElemWidth(buf_.size(), i - start + prefix_elems);
       bit_width = (std::max)(bit_width, elem_width);
       if (typed) {
         if (i == start) {
@@ -1511,7 +1593,8 @@
 
   typedef std::pair<size_t, size_t> StringOffset;
   struct StringOffsetCompare {
-    explicit StringOffsetCompare(const std::vector<uint8_t> &buf) : buf_(&buf) {}
+    explicit StringOffsetCompare(const std::vector<uint8_t> &buf)
+        : buf_(&buf) {}
     bool operator()(const StringOffset &a, const StringOffset &b) const {
       auto stra = reinterpret_cast<const char *>(
           flatbuffers::vector_data(*buf_) + a.first);
@@ -1531,8 +1614,8 @@
 
 }  // namespace flexbuffers
 
-#  if defined(_MSC_VER)
-#    pragma warning(pop)
-#  endif
+#if defined(_MSC_VER)
+#  pragma warning(pop)
+#endif
 
 #endif  // FLATBUFFERS_FLEXBUFFERS_H_
diff --git a/include/flatbuffers/grpc.h b/include/flatbuffers/grpc.h
index a75b67c..bd24c50 100644
--- a/include/flatbuffers/grpc.h
+++ b/include/flatbuffers/grpc.h
@@ -88,8 +88,7 @@
   SliceAllocator(const SliceAllocator &other) = delete;
   SliceAllocator &operator=(const SliceAllocator &other) = delete;
 
-  SliceAllocator(SliceAllocator &&other)
-    : slice_(grpc_empty_slice()) {
+  SliceAllocator(SliceAllocator &&other) : slice_(grpc_empty_slice()) {
     // default-construct and swap idiom
     swap(other);
   }
@@ -164,34 +163,36 @@
                        public FlatBufferBuilder {
  public:
   explicit MessageBuilder(uoffset_t initial_size = 1024)
-    : FlatBufferBuilder(initial_size, &slice_allocator_, false) {}
+      : FlatBufferBuilder(initial_size, &slice_allocator_, false) {}
 
   MessageBuilder(const MessageBuilder &other) = delete;
   MessageBuilder &operator=(const MessageBuilder &other) = delete;
 
   MessageBuilder(MessageBuilder &&other)
-    : FlatBufferBuilder(1024, &slice_allocator_, false) {
+      : FlatBufferBuilder(1024, &slice_allocator_, false) {
     // Default construct and swap idiom.
     Swap(other);
   }
 
   /// Create a MessageBuilder from a FlatBufferBuilder.
-  explicit MessageBuilder(FlatBufferBuilder &&src, void (*dealloc)(void*, size_t) = &DefaultAllocator::dealloc)
-    : FlatBufferBuilder(1024, &slice_allocator_, false) {
+  explicit MessageBuilder(FlatBufferBuilder &&src,
+                          void (*dealloc)(void *,
+                                          size_t) = &DefaultAllocator::dealloc)
+      : FlatBufferBuilder(1024, &slice_allocator_, false) {
     src.Swap(*this);
     src.SwapBufAllocator(*this);
     if (buf_.capacity()) {
-      uint8_t *buf = buf_.scratch_data();       // pointer to memory
-      size_t capacity = buf_.capacity();        // size of memory
+      uint8_t *buf = buf_.scratch_data();  // pointer to memory
+      size_t capacity = buf_.capacity();   // size of memory
       slice_allocator_.slice_ = grpc_slice_new_with_len(buf, capacity, dealloc);
-    }
-    else {
+    } else {
       slice_allocator_.slice_ = grpc_empty_slice();
     }
   }
 
   /// Move-assign a FlatBufferBuilder to a MessageBuilder.
-  /// Only FlatBufferBuilder with default allocator (basically, nullptr) is supported.
+  /// Only FlatBufferBuilder with default allocator (basically, nullptr) is
+  /// supported.
   MessageBuilder &operator=(FlatBufferBuilder &&src) {
     // Move construct a temporary and swap
     MessageBuilder temp(std::move(src));
@@ -209,10 +210,11 @@
   void Swap(MessageBuilder &other) {
     slice_allocator_.swap(other.slice_allocator_);
     FlatBufferBuilder::Swap(other);
-    // After swapping the FlatBufferBuilder, we swap back the allocator, which restores
-    // the original allocator back in place. This is necessary because MessageBuilder's
-    // allocator is its own member (SliceAllocatorMember). The allocator passed to
-    // FlatBufferBuilder::vector_downward must point to this member.
+    // After swapping the FlatBufferBuilder, we swap back the allocator, which
+    // restores the original allocator back in place. This is necessary because
+    // MessageBuilder's allocator is its own member (SliceAllocatorMember). The
+    // allocator passed to FlatBufferBuilder::vector_downward must point to this
+    // member.
     buf_.swap_allocator(other.buf_);
   }
 
@@ -232,10 +234,10 @@
   // flatbuffers-encoded region and wraps it in a `Message<T>` to handle buffer
   // ownership.
   template<class T> Message<T> GetMessage() {
-    auto buf_data = buf_.scratch_data();       // pointer to memory
-    auto buf_size = buf_.capacity();  // size of memory
-    auto msg_data = buf_.data();      // pointer to msg
-    auto msg_size = buf_.size();      // size of msg
+    auto buf_data = buf_.scratch_data();  // pointer to memory
+    auto buf_size = buf_.capacity();      // size of memory
+    auto msg_data = buf_.data();          // pointer to msg
+    auto msg_size = buf_.size();          // size of msg
     // Do some sanity checks on data/size
     FLATBUFFERS_ASSERT(msg_data);
     FLATBUFFERS_ASSERT(msg_size);
@@ -274,7 +276,7 @@
                                 grpc_byte_buffer **buffer, bool *own_buffer) {
     // We are passed in a `Message<T>`, which is a wrapper around a
     // `grpc_slice`. We extract it here using `BorrowSlice()`. The const cast
-    // is necesary because the `grpc_raw_byte_buffer_create` func expects
+    // is necessary because the `grpc_raw_byte_buffer_create` func expects
     // non-const slices in order to increment their refcounts.
     grpc_slice *slice = const_cast<grpc_slice *>(&msg.BorrowSlice());
     // Now use `grpc_raw_byte_buffer_create` to package the single slice into a
@@ -306,7 +308,7 @@
       grpc_byte_buffer_reader_init(&reader, buffer);
       grpc_slice slice = grpc_byte_buffer_reader_readall(&reader);
       grpc_byte_buffer_reader_destroy(&reader);
-      // We wrap a `Message<T>` around the slice, but dont increment refcount
+      // We wrap a `Message<T>` around the slice, but don't increment refcount
       *msg = flatbuffers::grpc::Message<T>(slice, false);
     }
     grpc_byte_buffer_destroy(buffer);
diff --git a/include/flatbuffers/hash.h b/include/flatbuffers/hash.h
index 16536cb..aebf071 100644
--- a/include/flatbuffers/hash.h
+++ b/include/flatbuffers/hash.h
@@ -57,17 +57,17 @@
   return hash;
 }
 
-template <> inline uint16_t HashFnv1<uint16_t>(const char *input) {
+template<> inline uint16_t HashFnv1<uint16_t>(const char *input) {
   uint32_t hash = HashFnv1<uint32_t>(input);
   return (hash >> 16) ^ (hash & 0xffff);
 }
 
-template <> inline uint16_t HashFnv1a<uint16_t>(const char *input) {
+template<> inline uint16_t HashFnv1a<uint16_t>(const char *input) {
   uint32_t hash = HashFnv1a<uint32_t>(input);
   return (hash >> 16) ^ (hash & 0xffff);
 }
 
-template <typename T> struct NamedHashFunction {
+template<typename T> struct NamedHashFunction {
   const char *name;
 
   typedef T (*HashFunction)(const char *);
@@ -75,7 +75,7 @@
 };
 
 const NamedHashFunction<uint16_t> kHashFunctions16[] = {
-  { "fnv1_16",  HashFnv1<uint16_t> },
+  { "fnv1_16", HashFnv1<uint16_t> },
   { "fnv1a_16", HashFnv1a<uint16_t> },
 };
 
diff --git a/include/flatbuffers/idl.h b/include/flatbuffers/idl.h
index 44e3566..a28745f 100644
--- a/include/flatbuffers/idl.h
+++ b/include/flatbuffers/idl.h
@@ -47,26 +47,26 @@
 // of type tokens.
 // clang-format off
 #define FLATBUFFERS_GEN_TYPES_SCALAR(TD) \
-  TD(NONE,   "",       uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte) \
-  TD(UTYPE,  "",       uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte) /* begin scalar/int */ \
-  TD(BOOL,   "bool",   uint8_t,  boolean,bool,    bool,   bool,    bool, Boolean) \
-  TD(CHAR,   "byte",   int8_t,   byte,   int8,    sbyte,  int8,    i8,   Byte) \
-  TD(UCHAR,  "ubyte",  uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte) \
-  TD(SHORT,  "short",  int16_t,  short,  int16,   short,  int16,   i16,  Short) \
-  TD(USHORT, "ushort", uint16_t, short,  uint16,  ushort, uint16,  u16,  UShort) \
-  TD(INT,    "int",    int32_t,  int,    int32,   int,    int32,   i32,  Int) \
-  TD(UINT,   "uint",   uint32_t, int,    uint32,  uint,   uint32,  u32,  UInt) \
-  TD(LONG,   "long",   int64_t,  long,   int64,   long,   int64,   i64,  Long) \
-  TD(ULONG,  "ulong",  uint64_t, long,   uint64,  ulong,  uint64,  u64,  ULong) /* end int */ \
-  TD(FLOAT,  "float",  float,    float,  float32, float,  float32, f32,  Float) /* begin float */ \
-  TD(DOUBLE, "double", double,   double, float64, double, float64, f64,  Double) /* end float/scalar */
+  TD(NONE,   "",       uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte, UInt8) \
+  TD(UTYPE,  "",       uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte, UInt8) /* begin scalar/int */ \
+  TD(BOOL,   "bool",   uint8_t,  boolean,bool,    bool,   bool,    bool, Boolean, Bool) \
+  TD(CHAR,   "byte",   int8_t,   byte,   int8,    sbyte,  int8,    i8,   Byte, Int8) \
+  TD(UCHAR,  "ubyte",  uint8_t,  byte,   byte,    byte,   uint8,   u8,   UByte, UInt8) \
+  TD(SHORT,  "short",  int16_t,  short,  int16,   short,  int16,   i16,  Short, Int16) \
+  TD(USHORT, "ushort", uint16_t, short,  uint16,  ushort, uint16,  u16,  UShort, UInt16) \
+  TD(INT,    "int",    int32_t,  int,    int32,   int,    int32,   i32,  Int, Int32) \
+  TD(UINT,   "uint",   uint32_t, int,    uint32,  uint,   uint32,  u32,  UInt, UInt32) \
+  TD(LONG,   "long",   int64_t,  long,   int64,   long,   int64,   i64,  Long, Int64) \
+  TD(ULONG,  "ulong",  uint64_t, long,   uint64,  ulong,  uint64,  u64,  ULong, UInt64) /* end int */ \
+  TD(FLOAT,  "float",  float,    float,  float32, float,  float32, f32,  Float, Float32) /* begin float */ \
+  TD(DOUBLE, "double", double,   double, float64, double, float64, f64,  Double, Double) /* end float/scalar */
 #define FLATBUFFERS_GEN_TYPES_POINTER(TD) \
-  TD(STRING, "string", Offset<void>, int, int, StringOffset, int, unused, Int) \
-  TD(VECTOR, "",       Offset<void>, int, int, VectorOffset, int, unused, Int) \
-  TD(STRUCT, "",       Offset<void>, int, int, int,          int, unused, Int) \
-  TD(UNION,  "",       Offset<void>, int, int, int,          int, unused, Int)
+  TD(STRING, "string", Offset<void>, int, int, StringOffset, int, unused, Int, Offset<String>) \
+  TD(VECTOR, "",       Offset<void>, int, int, VectorOffset, int, unused, Int, Offset<UOffset>) \
+  TD(STRUCT, "",       Offset<void>, int, int, int,          int, unused, Int, Offset<UOffset>) \
+  TD(UNION,  "",       Offset<void>, int, int, int,          int, unused, Int, Offset<UOffset>)
 #define FLATBUFFERS_GEN_TYPE_ARRAY(TD) \
-  TD(ARRAY,  "",       int,          int, int, int,          int, unused, Int)
+  TD(ARRAY,  "",       int,          int, int, int,          int, unused, Int, Offset<UOffset>)
 // The fields are:
 // - enum
 // - FlatBuffers schema type.
@@ -91,6 +91,20 @@
 }
 */
 
+// If not all FLATBUFFERS_GEN_() arguments are necessary for implementation
+// of FLATBUFFERS_TD, you can use a variadic macro (with __VA_ARGS__ if needed).
+// In the above example, only CTYPE is used to generate the code, it can be rewritten:
+
+/*
+switch (type) {
+  #define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, ...) \
+    case BASE_TYPE_ ## ENUM: \
+      // do something specific to CTYPE here
+    FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
+  #undef FLATBUFFERS_TD
+}
+*/
+
 #define FLATBUFFERS_GEN_TYPES(TD) \
         FLATBUFFERS_GEN_TYPES_SCALAR(TD) \
         FLATBUFFERS_GEN_TYPES_POINTER(TD) \
@@ -101,17 +115,15 @@
 __extension__  // Stop GCC complaining about trailing comma with -Wpendantic.
 #endif
 enum BaseType {
-  #define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE, PTYPE, \
-                         RTYPE, KTYPE) \
-      BASE_TYPE_ ## ENUM,
+  #define FLATBUFFERS_TD(ENUM, ...) \
+    BASE_TYPE_ ## ENUM,
     FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
   #undef FLATBUFFERS_TD
 };
 
-#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, GTYPE, NTYPE, PTYPE, \
-                       RTYPE, KTYPE) \
-    static_assert(sizeof(CTYPE) <= sizeof(largest_scalar_t), \
-                  "define largest_scalar_t as " #CTYPE);
+#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, ...) \
+  static_assert(sizeof(CTYPE) <= sizeof(largest_scalar_t), \
+                "define largest_scalar_t as " #CTYPE);
   FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
 #undef FLATBUFFERS_TD
 
@@ -227,7 +239,7 @@
 struct Namespace {
   Namespace() : from_table(0) {}
 
-  // Given a (potentally unqualified) name, return the "fully qualified" name
+  // Given a (potentially unqualified) name, return the "fully qualified" name
   // which has a full namespaced descriptor.
   // With max_components you can request less than the number of components
   // the current namespace has.
@@ -284,6 +296,7 @@
         shared(false),
         native_inline(false),
         flexbuffer(false),
+        optional(false),
         nested_flatbuffer(NULL),
         padding(0) {}
 
@@ -292,6 +305,10 @@
 
   bool Deserialize(Parser &parser, const reflection::Field *field);
 
+  bool IsScalarOptional() const {
+    return IsScalar(value.type.base_type) && optional;
+  }
+
   Value value;
   bool deprecated;  // Field is allowed to be present in old data, but can't be.
                     // written in new data nor accessed in new code.
@@ -302,6 +319,8 @@
   bool native_inline;  // Field will be defined inline (instead of as a pointer)
                        // for native tables if field is a struct.
   bool flexbuffer;     // This field contains FlexBuffer data.
+  bool optional;       // If True, this field is Null (as opposed to default
+                       // valued).
   StructDef *nested_flatbuffer;  // This field contains nested FlatBuffer data.
   size_t padding;                // Bytes to always pad after this field.
 };
@@ -338,45 +357,12 @@
   flatbuffers::unique_ptr<std::string> original_location;
 };
 
-inline bool IsStruct(const Type &type) {
-  return type.base_type == BASE_TYPE_STRUCT && type.struct_def->fixed;
-}
-
-inline bool IsVector(const Type &type) {
-  return type.base_type == BASE_TYPE_VECTOR;
-}
-
-inline bool IsArray(const Type &type) {
-  return type.base_type == BASE_TYPE_ARRAY;
-}
-
-inline bool IsSeries(const Type &type) {
-  return IsVector(type) || IsArray(type);
-}
-
-inline bool IsEnum(const Type &type) {
-  return type.enum_def != nullptr && IsInteger(type.base_type);
-}
-
-inline size_t InlineSize(const Type &type) {
-  return IsStruct(type)
-             ? type.struct_def->bytesize
-             : (IsArray(type)
-                    ? InlineSize(type.VectorType()) * type.fixed_length
-                    : SizeOf(type.base_type));
-}
-
-inline size_t InlineAlignment(const Type &type) {
-  return IsStruct(type)
-             ? type.struct_def->minalign
-             : (SizeOf(IsArray(type) ? type.element : type.base_type));
-}
-
 struct EnumDef;
 struct EnumValBuilder;
 
 struct EnumVal {
-  Offset<reflection::EnumVal> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
+  Offset<reflection::EnumVal> Serialize(FlatBufferBuilder *builder,
+                                        const Parser &parser) const;
 
   bool Deserialize(const Parser &parser, const reflection::EnumVal *val);
 
@@ -431,10 +417,7 @@
 
   size_t size() const { return vals.vec.size(); }
 
-  const std::vector<EnumVal *> &Vals() const {
-    FLATBUFFERS_ASSERT(false == vals.vec.empty());
-    return vals.vec;
-  }
+  const std::vector<EnumVal *> &Vals() const { return vals.vec; }
 
   const EnumVal *Lookup(const std::string &enum_name) const {
     return vals.Lookup(enum_name);
@@ -455,6 +438,52 @@
   SymbolTable<EnumVal> vals;
 };
 
+inline bool IsString(const Type &type) {
+  return type.base_type == BASE_TYPE_STRING;
+}
+
+inline bool IsStruct(const Type &type) {
+  return type.base_type == BASE_TYPE_STRUCT && type.struct_def->fixed;
+}
+
+inline bool IsUnion(const Type &type) {
+  return type.enum_def != nullptr && type.enum_def->is_union;
+}
+
+inline bool IsVector(const Type &type) {
+  return type.base_type == BASE_TYPE_VECTOR;
+}
+
+inline bool IsArray(const Type &type) {
+  return type.base_type == BASE_TYPE_ARRAY;
+}
+
+inline bool IsSeries(const Type &type) {
+  return IsVector(type) || IsArray(type);
+}
+
+inline bool IsEnum(const Type &type) {
+  return type.enum_def != nullptr && IsInteger(type.base_type);
+}
+
+inline size_t InlineSize(const Type &type) {
+  return IsStruct(type)
+             ? type.struct_def->bytesize
+             : (IsArray(type)
+                    ? InlineSize(type.VectorType()) * type.fixed_length
+                    : SizeOf(type.base_type));
+}
+
+inline size_t InlineAlignment(const Type &type) {
+  if (IsStruct(type)) {
+    return type.struct_def->minalign;
+  } else if (IsArray(type)) {
+    return IsStruct(type.VectorType()) ? type.struct_def->minalign
+                                       : SizeOf(type.element);
+  } else {
+    return SizeOf(type.base_type);
+  }
+}
 inline bool operator==(const EnumVal &lhs, const EnumVal &rhs) {
   return lhs.value == rhs.value;
 }
@@ -470,7 +499,8 @@
 }
 
 struct RPCCall : public Definition {
-  Offset<reflection::RPCCall> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
+  Offset<reflection::RPCCall> Serialize(FlatBufferBuilder *builder,
+                                        const Parser &parser) const;
 
   bool Deserialize(Parser &parser, const reflection::RPCCall *call);
 
@@ -478,7 +508,8 @@
 };
 
 struct ServiceDef : public Definition {
-  Offset<reflection::Service> Serialize(FlatBufferBuilder *builder, const Parser &parser) const;
+  Offset<reflection::Service> Serialize(FlatBufferBuilder *builder,
+                                        const Parser &parser) const;
   bool Deserialize(Parser &parser, const reflection::Service *service);
 
   SymbolTable<RPCCall> calls;
@@ -486,6 +517,9 @@
 
 // Container of options that may apply to any of the source/text generators.
 struct IDLOptions {
+  bool gen_jvmstatic;
+  // Use flexbuffers instead for binary and text generation
+  bool use_flexbuffers;
   bool strict_json;
   bool skip_js_exports;
   bool use_goog_js_export_format;
@@ -508,7 +542,9 @@
   std::string cpp_object_api_pointer_type;
   std::string cpp_object_api_string_type;
   bool cpp_object_api_string_flexible_constructor;
+  bool cpp_direct_copy;
   bool gen_nullable;
+  bool java_checkerframework;
   bool gen_generated;
   std::string object_prefix;
   std::string object_suffix;
@@ -519,6 +555,7 @@
   bool keep_include_path;
   bool binary_schema_comments;
   bool binary_schema_builtins;
+  bool binary_schema_gen_embed;
   bool skip_flatbuffers_import;
   std::string go_import;
   std::string go_namespace;
@@ -528,7 +565,13 @@
   bool size_prefixed;
   std::string root_type;
   bool force_defaults;
+  bool java_primitive_has_method;
+  bool cs_gen_json_serializer;
   std::vector<std::string> cpp_includes;
+  std::string cpp_std;
+  std::string proto_namespace_suffix;
+  std::string filename_suffix;
+  std::string filename_extension;
 
   // Possible options for the more general generator below.
   enum Language {
@@ -548,6 +591,7 @@
     kLobster = 1 << 13,
     kRust = 1 << 14,
     kKotlin = 1 << 15,
+    kSwift = 1 << 16,
     kMAX
   };
 
@@ -561,12 +605,18 @@
   // for code generation.
   unsigned long lang_to_generate;
 
-  // If set (default behavior), empty string and vector fields will be set to
-  // nullptr to make the flatbuffer more compact.
-  bool set_empty_to_null;
+  // If set (default behavior), empty string fields will be set to nullptr to
+  // make the flatbuffer more compact.
+  bool set_empty_strings_to_null;
+
+  // If set (default behavior), empty vector fields will be set to nullptr to
+  // make the flatbuffer more compact.
+  bool set_empty_vectors_to_null;
 
   IDLOptions()
-      : strict_json(false),
+      : gen_jvmstatic(false),
+        use_flexbuffers(false),
+        strict_json(false),
         skip_js_exports(false),
         use_goog_js_export_format(false),
         use_ES6_js_export_format(false),
@@ -587,7 +637,9 @@
         gen_compare(false),
         cpp_object_api_pointer_type("std::unique_ptr"),
         cpp_object_api_string_flexible_constructor(false),
+        cpp_direct_copy(true),
         gen_nullable(false),
+        java_checkerframework(false),
         gen_generated(false),
         object_suffix("T"),
         union_value_namespacing(true),
@@ -596,16 +648,22 @@
         keep_include_path(false),
         binary_schema_comments(false),
         binary_schema_builtins(false),
+        binary_schema_gen_embed(false),
         skip_flatbuffers_import(false),
         reexport_ts_modules(true),
         js_ts_short_names(false),
         protobuf_ascii_alike(false),
         size_prefixed(false),
         force_defaults(false),
+        java_primitive_has_method(false),
+        cs_gen_json_serializer(false),
+        filename_suffix("_generated"),
+        filename_extension(),
         lang(IDLOptions::kJava),
         mini_reflect(IDLOptions::kNone),
         lang_to_generate(0),
-        set_empty_to_null(true) {}
+        set_empty_strings_to_null(true),
+        set_empty_vectors_to_null(true) {}
 };
 
 // This encapsulates where the parser is in the current source file.
@@ -698,15 +756,14 @@
   explicit Parser(const IDLOptions &options = IDLOptions())
       : current_namespace_(nullptr),
         empty_namespace_(nullptr),
+        flex_builder_(256, flexbuffers::BUILDER_FLAG_SHARE_ALL),
         root_struct_def_(nullptr),
         opts(options),
         uses_flexbuffers_(false),
         source_(nullptr),
         anonymous_counter(0),
         recurse_protection_counter(0) {
-    if (opts.force_defaults) {
-      builder_.ForceDefaults(true);
-    }
+    if (opts.force_defaults) { builder_.ForceDefaults(true); }
     // Start out with the empty namespace being current.
     empty_namespace_ = new Namespace();
     namespaces_.push_back(empty_namespace_);
@@ -777,9 +834,9 @@
 
   // Fills internal structure as if the schema passed had been loaded by parsing
   // with Parse except that included filenames will not be populated.
-  bool Deserialize(const reflection::Schema* schema);
+  bool Deserialize(const reflection::Schema *schema);
 
-  Type* DeserializeType(const reflection::Type* type);
+  Type *DeserializeType(const reflection::Type *type);
 
   // Checks that the schema represented by this parser is a safe evolution
   // of the schema provided. Returns non-empty error on any problems.
@@ -796,6 +853,11 @@
 
   FLATBUFFERS_CHECKED_ERROR Error(const std::string &msg);
 
+  // @brief Verify that any of 'opts.lang_to_generate' supports Optional scalars
+  // in a schema.
+  // @param opts Options used to parce a schema and generate code.
+  static bool SupportsOptionalScalars(const flatbuffers::IDLOptions &opts);
+
  private:
   void Message(const std::string &msg);
   void Warning(const std::string &msg);
@@ -815,7 +877,7 @@
                                      const std::string &name, const Type &type,
                                      FieldDef **dest);
   FLATBUFFERS_CHECKED_ERROR ParseField(StructDef &struct_def);
-  FLATBUFFERS_CHECKED_ERROR ParseString(Value &val);
+  FLATBUFFERS_CHECKED_ERROR ParseString(Value &val, bool use_string_pooling);
   FLATBUFFERS_CHECKED_ERROR ParseComma();
   FLATBUFFERS_CHECKED_ERROR ParseAnyValue(Value &val, FieldDef *field,
                                           size_t parent_fieldn,
@@ -836,16 +898,20 @@
   FLATBUFFERS_CHECKED_ERROR ParseVector(const Type &type, uoffset_t *ovalue,
                                         FieldDef *field, size_t fieldn);
   FLATBUFFERS_CHECKED_ERROR ParseArray(Value &array);
-  FLATBUFFERS_CHECKED_ERROR ParseNestedFlatbuffer(Value &val, FieldDef *field,
-                                                  size_t fieldn,
-                                                  const StructDef *parent_struct_def);
+  FLATBUFFERS_CHECKED_ERROR ParseNestedFlatbuffer(
+      Value &val, FieldDef *field, size_t fieldn,
+      const StructDef *parent_struct_def);
   FLATBUFFERS_CHECKED_ERROR ParseMetaData(SymbolTable<Value> *attributes);
-  FLATBUFFERS_CHECKED_ERROR TryTypedValue(const std::string *name, int dtoken, bool check, Value &e,
-                                          BaseType req, bool *destmatch);
-  FLATBUFFERS_CHECKED_ERROR ParseHash(Value &e, FieldDef* field);
+  FLATBUFFERS_CHECKED_ERROR TryTypedValue(const std::string *name, int dtoken,
+                                          bool check, Value &e, BaseType req,
+                                          bool *destmatch);
+  FLATBUFFERS_CHECKED_ERROR ParseHash(Value &e, FieldDef *field);
   FLATBUFFERS_CHECKED_ERROR TokenError();
-  FLATBUFFERS_CHECKED_ERROR ParseSingleValue(const std::string *name, Value &e, bool check_now);
-  FLATBUFFERS_CHECKED_ERROR ParseEnumFromString(const Type &type, std::string *result);
+  FLATBUFFERS_CHECKED_ERROR ParseSingleValue(const std::string *name, Value &e,
+                                             bool check_now);
+  FLATBUFFERS_CHECKED_ERROR ParseFunction(const std::string *name, Value &e);
+  FLATBUFFERS_CHECKED_ERROR ParseEnumFromString(const Type &type,
+                                                std::string *result);
   StructDef *LookupCreateStruct(const std::string &name,
                                 bool create_if_new = true,
                                 bool definition = false);
@@ -853,8 +919,7 @@
   FLATBUFFERS_CHECKED_ERROR ParseNamespace();
   FLATBUFFERS_CHECKED_ERROR StartStruct(const std::string &name,
                                         StructDef **dest);
-  FLATBUFFERS_CHECKED_ERROR StartEnum(const std::string &name,
-                                      bool is_union,
+  FLATBUFFERS_CHECKED_ERROR StartEnum(const std::string &name, bool is_union,
                                       EnumDef **dest);
   FLATBUFFERS_CHECKED_ERROR ParseDecl();
   FLATBUFFERS_CHECKED_ERROR ParseService();
@@ -870,19 +935,19 @@
   FLATBUFFERS_CHECKED_ERROR StartParseFile(const char *source,
                                            const char *source_filename);
   FLATBUFFERS_CHECKED_ERROR ParseRoot(const char *_source,
-                                    const char **include_paths,
-                                    const char *source_filename);
+                                      const char **include_paths,
+                                      const char *source_filename);
   FLATBUFFERS_CHECKED_ERROR DoParse(const char *_source,
-                                           const char **include_paths,
-                                           const char *source_filename,
-                                           const char *include_filename);
-  FLATBUFFERS_CHECKED_ERROR CheckClash(std::vector<FieldDef*> &fields,
+                                    const char **include_paths,
+                                    const char *source_filename,
+                                    const char *include_filename);
+  FLATBUFFERS_CHECKED_ERROR CheckClash(std::vector<FieldDef *> &fields,
                                        StructDef *struct_def,
-                                       const char *suffix,
-                                       BaseType baseType);
+                                       const char *suffix, BaseType baseType);
 
   bool SupportsAdvancedUnionFeatures() const;
   bool SupportsAdvancedArrayFeatures() const;
+  bool SupportsOptionalScalars() const;
   Namespace *UniqueNamespace(Namespace *ns);
 
   FLATBUFFERS_CHECKED_ERROR RecurseError();
@@ -896,9 +961,11 @@
   std::vector<Namespace *> namespaces_;
   Namespace *current_namespace_;
   Namespace *empty_namespace_;
-  std::string error_;         // User readable error_ if Parse() == false
+  std::string error_;  // User readable error_ if Parse() == false
 
   FlatBufferBuilder builder_;  // any data contained in the file
+  flexbuffers::Builder flex_builder_;
+  flexbuffers::Reference flex_root_;
   StructDef *root_struct_def_;
   std::string file_identifier_;
   std::string file_extension_;
@@ -927,6 +994,8 @@
 
 extern std::string MakeCamel(const std::string &in, bool first = true);
 
+extern std::string MakeScreamingCamel(const std::string &in);
+
 // Generate text (JSON) from a given FlatBuffer, and a given Parser
 // object that has been populated with the corresponding schema.
 // If ident_step is 0, no indentation will be generated. Additionally,
@@ -935,159 +1004,160 @@
 // strict_json adds "quotes" around field names if true.
 // If the flatbuffer cannot be encoded in JSON (e.g., it contains non-UTF-8
 // byte arrays in String values), returns false.
-extern bool GenerateTextFromTable(const Parser &parser,
-                                  const void *table,
+extern bool GenerateTextFromTable(const Parser &parser, const void *table,
                                   const std::string &tablename,
                                   std::string *text);
-extern bool GenerateText(const Parser &parser,
-                         const void *flatbuffer,
+extern bool GenerateText(const Parser &parser, const void *flatbuffer,
                          std::string *text);
-extern bool GenerateTextFile(const Parser &parser,
-                             const std::string &path,
+extern bool GenerateTextFile(const Parser &parser, const std::string &path,
                              const std::string &file_name);
 
+// Generate Json schema to string
+// See idl_gen_json_schema.cpp.
+extern bool GenerateJsonSchema(const Parser &parser, std::string *json);
+
 // Generate binary files from a given FlatBuffer, and a given Parser
 // object that has been populated with the corresponding schema.
-// See idl_gen_general.cpp.
-extern bool GenerateBinary(const Parser &parser,
-                           const std::string &path,
+// See code_generators.cpp.
+extern bool GenerateBinary(const Parser &parser, const std::string &path,
                            const std::string &file_name);
 
 // Generate a C++ header from the definitions in the Parser object.
 // See idl_gen_cpp.
-extern bool GenerateCPP(const Parser &parser,
-                        const std::string &path,
+extern bool GenerateCPP(const Parser &parser, const std::string &path,
                         const std::string &file_name);
 
-extern bool GenerateDart(const Parser &parser,
-                         const std::string &path,
+// Generate C# files from the definitions in the Parser object.
+// See idl_gen_csharp.cpp.
+extern bool GenerateCSharp(const Parser &parser, const std::string &path,
+                           const std::string &file_name);
+
+extern bool GenerateDart(const Parser &parser, const std::string &path,
                          const std::string &file_name);
 
-// Generate JavaScript or TypeScript code from the definitions in the Parser object.
-// See idl_gen_js.
-extern bool GenerateJSTS(const Parser &parser,
-                       const std::string &path,
-                       const std::string &file_name);
+// Generate Java files from the definitions in the Parser object.
+// See idl_gen_java.cpp.
+extern bool GenerateJava(const Parser &parser, const std::string &path,
+                         const std::string &file_name);
+
+// Generate JavaScript or TypeScript code from the definitions in the Parser
+// object. See idl_gen_js.
+extern bool GenerateJSTS(const Parser &parser, const std::string &path,
+                         const std::string &file_name);
 
 // Generate Go files from the definitions in the Parser object.
 // See idl_gen_go.cpp.
-extern bool GenerateGo(const Parser &parser,
-                       const std::string &path,
+extern bool GenerateGo(const Parser &parser, const std::string &path,
                        const std::string &file_name);
 
 // Generate Php code from the definitions in the Parser object.
 // See idl_gen_php.
-extern bool GeneratePhp(const Parser &parser,
-                        const std::string &path,
+extern bool GeneratePhp(const Parser &parser, const std::string &path,
                         const std::string &file_name);
 
 // Generate Python files from the definitions in the Parser object.
 // See idl_gen_python.cpp.
-extern bool GeneratePython(const Parser &parser,
-                           const std::string &path,
+extern bool GeneratePython(const Parser &parser, const std::string &path,
                            const std::string &file_name);
 
 // Generate Lobster files from the definitions in the Parser object.
 // See idl_gen_lobster.cpp.
-extern bool GenerateLobster(const Parser &parser,
-                            const std::string &path,
+extern bool GenerateLobster(const Parser &parser, const std::string &path,
                             const std::string &file_name);
 
 // Generate Lua files from the definitions in the Parser object.
 // See idl_gen_lua.cpp.
-extern bool GenerateLua(const Parser &parser,
-                      const std::string &path,
-                      const std::string &file_name);
+extern bool GenerateLua(const Parser &parser, const std::string &path,
+                        const std::string &file_name);
 
 // Generate Rust files from the definitions in the Parser object.
 // See idl_gen_rust.cpp.
-extern bool GenerateRust(const Parser &parser,
-                         const std::string &path,
+extern bool GenerateRust(const Parser &parser, const std::string &path,
                          const std::string &file_name);
 
 // Generate Json schema file
 // See idl_gen_json_schema.cpp.
-extern bool GenerateJsonSchema(const Parser &parser,
-                           const std::string &path,
-                           const std::string &file_name);
+extern bool GenerateJsonSchema(const Parser &parser, const std::string &path,
+                               const std::string &file_name);
 
 extern bool GenerateKotlin(const Parser &parser, const std::string &path,
                            const std::string &file_name);
 
-// Generate Java/C#/.. files from the definitions in the Parser object.
-// See idl_gen_general.cpp.
-extern bool GenerateGeneral(const Parser &parser,
-                            const std::string &path,
-                            const std::string &file_name);
+// Generate Swift classes.
+// See idl_gen_swift.cpp
+extern bool GenerateSwift(const Parser &parser, const std::string &path,
+                          const std::string &file_name);
 
 // Generate a schema file from the internal representation, useful after
 // parsing a .proto schema.
 extern std::string GenerateFBS(const Parser &parser,
                                const std::string &file_name);
-extern bool GenerateFBS(const Parser &parser,
-                        const std::string &path,
+extern bool GenerateFBS(const Parser &parser, const std::string &path,
                         const std::string &file_name);
 
 // Generate a make rule for the generated JavaScript or TypeScript code.
 // See idl_gen_js.cpp.
-extern std::string JSTSMakeRule(const Parser &parser,
-                              const std::string &path,
-                              const std::string &file_name);
+extern std::string JSTSMakeRule(const Parser &parser, const std::string &path,
+                                const std::string &file_name);
 
 // Generate a make rule for the generated C++ header.
 // See idl_gen_cpp.cpp.
-extern std::string CPPMakeRule(const Parser &parser,
-                               const std::string &path,
+extern std::string CPPMakeRule(const Parser &parser, const std::string &path,
                                const std::string &file_name);
 
 // Generate a make rule for the generated Dart code
 // see idl_gen_dart.cpp
-extern std::string DartMakeRule(const Parser &parser,
-                                const std::string &path,
+extern std::string DartMakeRule(const Parser &parser, const std::string &path,
                                 const std::string &file_name);
 
 // Generate a make rule for the generated Rust code.
 // See idl_gen_rust.cpp.
-extern std::string RustMakeRule(const Parser &parser,
-                                const std::string &path,
+extern std::string RustMakeRule(const Parser &parser, const std::string &path,
                                 const std::string &file_name);
 
-// Generate a make rule for the generated Java/C#/... files.
-// See idl_gen_general.cpp.
-extern std::string GeneralMakeRule(const Parser &parser,
-                                   const std::string &path,
-                                   const std::string &file_name);
+// Generate a make rule for generated Java or C# files.
+// See code_generators.cpp.
+extern std::string JavaCSharpMakeRule(const Parser &parser,
+                                      const std::string &path,
+                                      const std::string &file_name);
 
 // Generate a make rule for the generated text (JSON) files.
 // See idl_gen_text.cpp.
-extern std::string TextMakeRule(const Parser &parser,
-                                const std::string &path,
+extern std::string TextMakeRule(const Parser &parser, const std::string &path,
                                 const std::string &file_names);
 
 // Generate a make rule for the generated binary files.
-// See idl_gen_general.cpp.
-extern std::string BinaryMakeRule(const Parser &parser,
-                                  const std::string &path,
+// See code_generators.cpp.
+extern std::string BinaryMakeRule(const Parser &parser, const std::string &path,
                                   const std::string &file_name);
 
 // Generate GRPC Cpp interfaces.
 // See idl_gen_grpc.cpp.
-bool GenerateCppGRPC(const Parser &parser,
-                     const std::string &path,
+bool GenerateCppGRPC(const Parser &parser, const std::string &path,
                      const std::string &file_name);
 
 // Generate GRPC Go interfaces.
 // See idl_gen_grpc.cpp.
-bool GenerateGoGRPC(const Parser &parser,
-                    const std::string &path,
+bool GenerateGoGRPC(const Parser &parser, const std::string &path,
                     const std::string &file_name);
 
 // Generate GRPC Java classes.
 // See idl_gen_grpc.cpp
-bool GenerateJavaGRPC(const Parser &parser,
-                      const std::string &path,
+bool GenerateJavaGRPC(const Parser &parser, const std::string &path,
                       const std::string &file_name);
 
+// Generate GRPC Python interfaces.
+// See idl_gen_grpc.cpp.
+bool GeneratePythonGRPC(const Parser &parser, const std::string &path,
+                        const std::string &file_name);
+
+// Generate GRPC Swift interfaces.
+// See idl_gen_grpc.cpp.
+extern bool GenerateSwiftGRPC(const Parser &parser, const std::string &path,
+                              const std::string &file_name);
+
+extern bool GenerateTSGRPC(const Parser &parser, const std::string &path,
+                             const std::string &file_name);
 }  // namespace flatbuffers
 
 #endif  // FLATBUFFERS_IDL_H_
diff --git a/include/flatbuffers/minireflect.h b/include/flatbuffers/minireflect.h
index 9d648ec..26fd86c 100644
--- a/include/flatbuffers/minireflect.h
+++ b/include/flatbuffers/minireflect.h
@@ -38,7 +38,7 @@
   // These mark the scope of a table or struct.
   virtual void StartSequence() {}
   virtual void EndSequence() {}
-  // Called for each field regardless of wether it is present or not.
+  // Called for each field regardless of whether it is present or not.
   // If not present, val == nullptr. set_idx is the index of all set fields.
   virtual void Field(size_t /*field_idx*/, size_t /*set_idx*/,
                      ElementaryType /*type*/, bool /*is_vector*/,
@@ -88,7 +88,8 @@
       switch (type_table->st) {
         case ST_TABLE:
         case ST_UNION: return 4;
-        case ST_STRUCT: return static_cast<size_t>(type_table->values[type_table->num_elems]);
+        case ST_STRUCT:
+          return static_cast<size_t>(type_table->values[type_table->num_elems]);
         default: FLATBUFFERS_ASSERT(false); return 1;
       }
     default: FLATBUFFERS_ASSERT(false); return 1;
@@ -233,10 +234,11 @@
   visitor->StartSequence();
   const uint8_t *prev_val = nullptr;
   size_t set_idx = 0;
+  size_t array_idx = 0;
   for (size_t i = 0; i < type_table->num_elems; i++) {
     auto type_code = type_table->type_codes[i];
     auto type = static_cast<ElementaryType>(type_code.base_type);
-    auto is_vector = type_code.is_vector != 0;
+    auto is_repeating = type_code.is_repeating != 0;
     auto ref_idx = type_code.sequence_ref;
     const TypeTable *ref = nullptr;
     if (ref_idx >= 0) { ref = type_table->type_refs[ref_idx](); }
@@ -248,15 +250,25 @@
     } else {
       val = obj + type_table->values[i];
     }
-    visitor->Field(i, set_idx, type, is_vector, ref, name, val);
+    visitor->Field(i, set_idx, type, is_repeating, ref, name, val);
     if (val) {
       set_idx++;
-      if (is_vector) {
-        val += ReadScalar<uoffset_t>(val);
-        auto vec = reinterpret_cast<const Vector<uint8_t> *>(val);
+      if (is_repeating) {
+        auto elem_ptr = val;
+        size_t size = 0;
+        if (type_table->st == ST_TABLE) {
+          // variable length vector
+          val += ReadScalar<uoffset_t>(val);
+          auto vec = reinterpret_cast<const Vector<uint8_t> *>(val);
+          elem_ptr = vec->Data();
+          size = vec->size();
+        } else {
+          // otherwise fixed size array
+          size = type_table->array_sizes[array_idx];
+          ++array_idx;
+        }
         visitor->StartVector();
-        auto elem_ptr = vec->Data();
-        for (size_t j = 0; j < vec->size(); j++) {
+        for (size_t j = 0; j < size; j++) {
           visitor->Element(j, type, ref, elem_ptr);
           IterateValue(type, elem_ptr, ref, prev_val, static_cast<soffset_t>(j),
                        visitor);
diff --git a/include/flatbuffers/pch/flatc_pch.h b/include/flatbuffers/pch/flatc_pch.h
new file mode 100644
index 0000000..7713279
--- /dev/null
+++ b/include/flatbuffers/pch/flatc_pch.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLATBUFFERS_FLATC_PCH_H_
+#define FLATBUFFERS_FLATC_PCH_H_
+
+// stl
+#include <cmath>
+#include <sstream>
+#include <cassert>
+#include <unordered_set>
+#include <unordered_map>
+#include <iostream>
+#include <functional>
+#include <set>
+#include <iterator>
+#include <tuple>
+
+// flatbuffers
+#include "flatbuffers/pch/pch.h"
+#include "flatbuffers/code_generators.h"
+#include "flatbuffers/flatbuffers.h"
+#include "flatbuffers/flexbuffers.h"
+#include "flatbuffers/idl.h"
+
+#endif // FLATBUFFERS_FLATC_PCH_H_
diff --git a/include/flatbuffers/pch/pch.h b/include/flatbuffers/pch/pch.h
new file mode 100644
index 0000000..804e99e
--- /dev/null
+++ b/include/flatbuffers/pch/pch.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLATBUFFERS_PCH_H_
+#define FLATBUFFERS_PCH_H_
+
+// stl
+#include <cstdint>
+#include <cstring>
+#include <algorithm>
+#include <list>
+#include <string>
+#include <utility>
+#include <iomanip>
+#include <map>
+#include <memory>
+#include <limits>
+#include <stack>
+#include <vector>
+#include <type_traits>
+
+// flatbuffers
+#include "flatbuffers/util.h"
+
+#endif // FLATBUFFERS_PCH_H_
diff --git a/include/flatbuffers/reflection.h b/include/flatbuffers/reflection.h
index 580ae62..70d9971 100644
--- a/include/flatbuffers/reflection.h
+++ b/include/flatbuffers/reflection.h
@@ -46,7 +46,30 @@
 // Size of a basic type, don't use with structs.
 inline size_t GetTypeSize(reflection::BaseType base_type) {
   // This needs to correspond to the BaseType enum.
-  static size_t sizes[] = { 0, 1, 1, 1, 1, 2, 2, 4, 4, 8, 8, 4, 8, 4, 4, 4, 4 };
+  static size_t sizes[] = {
+    0, // None
+    1, // UType
+    1, // Bool
+    1, // Byte
+    1, // UByte
+    2, // Short
+    2, // UShort
+    4, // Int
+    4, // UInt
+    8, // Long
+    8, // ULong
+    4, // Float
+    8, // Double
+    4, // String
+    4, // Vector
+    4, // Obj
+    4, // Union
+    0, // Array. Only used in structs. 0 was chosen to prevent out-of-bounds errors.
+
+    0  // MaxBaseType. This must be kept the last entry in this array.
+    };
+  static_assert(sizeof(sizes) / sizeof(size_t) == reflection::MaxBaseType + 1,
+                "Size of sizes[] array does not match the count of BaseType enum values.");
   return sizes[base_type];
 }
 
@@ -228,7 +251,7 @@
 template<typename T>
 T *GetAnyVectorElemPointer(const VectorOfAny *vec, size_t i) {
   auto elem_ptr = vec->Data() + sizeof(uoffset_t) * i;
-  return reinterpret_cast<T*>(elem_ptr + ReadScalar<uoffset_t>(elem_ptr));
+  return reinterpret_cast<T *>(elem_ptr + ReadScalar<uoffset_t>(elem_ptr));
 }
 
 // Get the inline-address of a vector element. Useful for Structs (pass Struct
@@ -362,7 +385,6 @@
         reinterpret_cast<uint8_t *>(flatbuffers::vector_data(vec_)) + offset_);
   }
   T *operator->() const { return operator*(); }
-  void operator=(const pointer_inside_vector &piv);
 
  private:
   size_t offset_;
@@ -470,7 +492,8 @@
 // buf should point to the start of flatbuffer data.
 // length specifies the size of the flatbuffer data.
 bool Verify(const reflection::Schema &schema, const reflection::Object &root,
-            const uint8_t *buf, size_t length);
+            const uint8_t *buf, size_t length, uoffset_t max_depth = 64,
+            uoffset_t max_tables = 1000000);
 
 }  // namespace flatbuffers
 
diff --git a/include/flatbuffers/reflection_generated.h b/include/flatbuffers/reflection_generated.h
index 0e73a0f..b98afd6 100644
--- a/include/flatbuffers/reflection_generated.h
+++ b/include/flatbuffers/reflection_generated.h
@@ -9,22 +9,31 @@
 namespace reflection {
 
 struct Type;
+struct TypeBuilder;
 
 struct KeyValue;
+struct KeyValueBuilder;
 
 struct EnumVal;
+struct EnumValBuilder;
 
 struct Enum;
+struct EnumBuilder;
 
 struct Field;
+struct FieldBuilder;
 
 struct Object;
+struct ObjectBuilder;
 
 struct RPCCall;
+struct RPCCallBuilder;
 
 struct Service;
+struct ServiceBuilder;
 
 struct Schema;
+struct SchemaBuilder;
 
 enum BaseType {
   None = 0,
@@ -44,10 +53,11 @@
   Vector = 14,
   Obj = 15,
   Union = 16,
-  Array = 17
+  Array = 17,
+  MaxBaseType = 18
 };
 
-inline const BaseType (&EnumValuesBaseType())[18] {
+inline const BaseType (&EnumValuesBaseType())[19] {
   static const BaseType values[] = {
     None,
     UType,
@@ -66,13 +76,14 @@
     Vector,
     Obj,
     Union,
-    Array
+    Array,
+    MaxBaseType
   };
   return values;
 }
 
 inline const char * const *EnumNamesBaseType() {
-  static const char * const names[19] = {
+  static const char * const names[20] = {
     "None",
     "UType",
     "Bool",
@@ -91,18 +102,20 @@
     "Obj",
     "Union",
     "Array",
+    "MaxBaseType",
     nullptr
   };
   return names;
 }
 
 inline const char *EnumNameBaseType(BaseType e) {
-  if (e < None || e > Array) return "";
+  if (flatbuffers::IsOutRange(e, None, MaxBaseType)) return "";
   const size_t index = static_cast<size_t>(e);
   return EnumNamesBaseType()[index];
 }
 
 struct Type FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef TypeBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_BASE_TYPE = 4,
     VT_ELEMENT = 6,
@@ -132,6 +145,7 @@
 };
 
 struct TypeBuilder {
+  typedef Type Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_base_type(reflection::BaseType base_type) {
@@ -150,7 +164,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  TypeBuilder &operator=(const TypeBuilder &);
   flatbuffers::Offset<Type> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Type>(end);
@@ -173,6 +186,7 @@
 }
 
 struct KeyValue FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef KeyValueBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_KEY = 4,
     VT_VALUE = 6
@@ -200,6 +214,7 @@
 };
 
 struct KeyValueBuilder {
+  typedef KeyValue Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_key(flatbuffers::Offset<flatbuffers::String> key) {
@@ -212,7 +227,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  KeyValueBuilder &operator=(const KeyValueBuilder &);
   flatbuffers::Offset<KeyValue> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<KeyValue>(end);
@@ -244,6 +258,7 @@
 }
 
 struct EnumVal FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef EnumValBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_VALUE = 6,
@@ -289,6 +304,7 @@
 };
 
 struct EnumValBuilder {
+  typedef EnumVal Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -310,7 +326,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  EnumValBuilder &operator=(const EnumValBuilder &);
   flatbuffers::Offset<EnumVal> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<EnumVal>(end);
@@ -354,6 +369,7 @@
 }
 
 struct Enum FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef EnumBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_VALUES = 6,
@@ -407,6 +423,7 @@
 };
 
 struct EnumBuilder {
+  typedef Enum Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -431,7 +448,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  EnumBuilder &operator=(const EnumBuilder &);
   flatbuffers::Offset<Enum> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Enum>(end);
@@ -463,14 +479,14 @@
 inline flatbuffers::Offset<Enum> CreateEnumDirect(
     flatbuffers::FlatBufferBuilder &_fbb,
     const char *name = nullptr,
-    const std::vector<flatbuffers::Offset<reflection::EnumVal>> *values = nullptr,
+    std::vector<flatbuffers::Offset<reflection::EnumVal>> *values = nullptr,
     bool is_union = false,
     flatbuffers::Offset<reflection::Type> underlying_type = 0,
-    const std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
+    std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
     const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
-  auto values__ = values ? _fbb.CreateVector<flatbuffers::Offset<reflection::EnumVal>>(*values) : 0;
-  auto attributes__ = attributes ? _fbb.CreateVector<flatbuffers::Offset<reflection::KeyValue>>(*attributes) : 0;
+  auto values__ = values ? _fbb.CreateVectorOfSortedTables<reflection::EnumVal>(values) : 0;
+  auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0;
   return reflection::CreateEnum(
       _fbb,
@@ -483,6 +499,7 @@
 }
 
 struct Field FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef FieldBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_TYPE = 6,
@@ -494,7 +511,8 @@
     VT_REQUIRED = 18,
     VT_KEY = 20,
     VT_ATTRIBUTES = 22,
-    VT_DOCUMENTATION = 24
+    VT_DOCUMENTATION = 24,
+    VT_OPTIONAL = 26
   };
   const flatbuffers::String *name() const {
     return GetPointer<const flatbuffers::String *>(VT_NAME);
@@ -535,6 +553,9 @@
   const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *documentation() const {
     return GetPointer<const flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>> *>(VT_DOCUMENTATION);
   }
+  bool optional() const {
+    return GetField<uint8_t>(VT_OPTIONAL, 0) != 0;
+  }
   bool Verify(flatbuffers::Verifier &verifier) const {
     return VerifyTableStart(verifier) &&
            VerifyOffsetRequired(verifier, VT_NAME) &&
@@ -554,11 +575,13 @@
            VerifyOffset(verifier, VT_DOCUMENTATION) &&
            verifier.VerifyVector(documentation()) &&
            verifier.VerifyVectorOfStrings(documentation()) &&
+           VerifyField<uint8_t>(verifier, VT_OPTIONAL) &&
            verifier.EndTable();
   }
 };
 
 struct FieldBuilder {
+  typedef Field Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -594,11 +617,13 @@
   void add_documentation(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation) {
     fbb_.AddOffset(Field::VT_DOCUMENTATION, documentation);
   }
+  void add_optional(bool optional) {
+    fbb_.AddElement<uint8_t>(Field::VT_OPTIONAL, static_cast<uint8_t>(optional), 0);
+  }
   explicit FieldBuilder(flatbuffers::FlatBufferBuilder &_fbb)
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  FieldBuilder &operator=(const FieldBuilder &);
   flatbuffers::Offset<Field> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Field>(end);
@@ -620,7 +645,8 @@
     bool required = false,
     bool key = false,
     flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<reflection::KeyValue>>> attributes = 0,
-    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation = 0) {
+    flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<flatbuffers::String>>> documentation = 0,
+    bool optional = false) {
   FieldBuilder builder_(_fbb);
   builder_.add_default_real(default_real);
   builder_.add_default_integer(default_integer);
@@ -630,6 +656,7 @@
   builder_.add_name(name);
   builder_.add_offset(offset);
   builder_.add_id(id);
+  builder_.add_optional(optional);
   builder_.add_key(key);
   builder_.add_required(required);
   builder_.add_deprecated(deprecated);
@@ -647,10 +674,11 @@
     bool deprecated = false,
     bool required = false,
     bool key = false,
-    const std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
-    const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
+    std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
+    const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr,
+    bool optional = false) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
-  auto attributes__ = attributes ? _fbb.CreateVector<flatbuffers::Offset<reflection::KeyValue>>(*attributes) : 0;
+  auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0;
   return reflection::CreateField(
       _fbb,
@@ -664,10 +692,12 @@
       required,
       key,
       attributes__,
-      documentation__);
+      documentation__,
+      optional);
 }
 
 struct Object FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef ObjectBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_FIELDS = 6,
@@ -725,6 +755,7 @@
 };
 
 struct ObjectBuilder {
+  typedef Object Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -752,7 +783,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  ObjectBuilder &operator=(const ObjectBuilder &);
   flatbuffers::Offset<Object> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Object>(end);
@@ -785,15 +815,15 @@
 inline flatbuffers::Offset<Object> CreateObjectDirect(
     flatbuffers::FlatBufferBuilder &_fbb,
     const char *name = nullptr,
-    const std::vector<flatbuffers::Offset<reflection::Field>> *fields = nullptr,
+    std::vector<flatbuffers::Offset<reflection::Field>> *fields = nullptr,
     bool is_struct = false,
     int32_t minalign = 0,
     int32_t bytesize = 0,
-    const std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
+    std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
     const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
-  auto fields__ = fields ? _fbb.CreateVector<flatbuffers::Offset<reflection::Field>>(*fields) : 0;
-  auto attributes__ = attributes ? _fbb.CreateVector<flatbuffers::Offset<reflection::KeyValue>>(*attributes) : 0;
+  auto fields__ = fields ? _fbb.CreateVectorOfSortedTables<reflection::Field>(fields) : 0;
+  auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0;
   return reflection::CreateObject(
       _fbb,
@@ -807,6 +837,7 @@
 }
 
 struct RPCCall FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef RPCCallBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_REQUEST = 6,
@@ -854,6 +885,7 @@
 };
 
 struct RPCCallBuilder {
+  typedef RPCCall Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -875,7 +907,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  RPCCallBuilder &operator=(const RPCCallBuilder &);
   flatbuffers::Offset<RPCCall> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<RPCCall>(end);
@@ -907,10 +938,10 @@
     const char *name = nullptr,
     flatbuffers::Offset<reflection::Object> request = 0,
     flatbuffers::Offset<reflection::Object> response = 0,
-    const std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
+    std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
     const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
-  auto attributes__ = attributes ? _fbb.CreateVector<flatbuffers::Offset<reflection::KeyValue>>(*attributes) : 0;
+  auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0;
   return reflection::CreateRPCCall(
       _fbb,
@@ -922,6 +953,7 @@
 }
 
 struct Service FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef ServiceBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_NAME = 4,
     VT_CALLS = 6,
@@ -964,6 +996,7 @@
 };
 
 struct ServiceBuilder {
+  typedef Service Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_name(flatbuffers::Offset<flatbuffers::String> name) {
@@ -982,7 +1015,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  ServiceBuilder &operator=(const ServiceBuilder &);
   flatbuffers::Offset<Service> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Service>(end);
@@ -1008,12 +1040,12 @@
 inline flatbuffers::Offset<Service> CreateServiceDirect(
     flatbuffers::FlatBufferBuilder &_fbb,
     const char *name = nullptr,
-    const std::vector<flatbuffers::Offset<reflection::RPCCall>> *calls = nullptr,
-    const std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
+    std::vector<flatbuffers::Offset<reflection::RPCCall>> *calls = nullptr,
+    std::vector<flatbuffers::Offset<reflection::KeyValue>> *attributes = nullptr,
     const std::vector<flatbuffers::Offset<flatbuffers::String>> *documentation = nullptr) {
   auto name__ = name ? _fbb.CreateString(name) : 0;
-  auto calls__ = calls ? _fbb.CreateVector<flatbuffers::Offset<reflection::RPCCall>>(*calls) : 0;
-  auto attributes__ = attributes ? _fbb.CreateVector<flatbuffers::Offset<reflection::KeyValue>>(*attributes) : 0;
+  auto calls__ = calls ? _fbb.CreateVectorOfSortedTables<reflection::RPCCall>(calls) : 0;
+  auto attributes__ = attributes ? _fbb.CreateVectorOfSortedTables<reflection::KeyValue>(attributes) : 0;
   auto documentation__ = documentation ? _fbb.CreateVector<flatbuffers::Offset<flatbuffers::String>>(*documentation) : 0;
   return reflection::CreateService(
       _fbb,
@@ -1024,6 +1056,7 @@
 }
 
 struct Schema FLATBUFFERS_FINAL_CLASS : private flatbuffers::Table {
+  typedef SchemaBuilder Builder;
   enum FlatBuffersVTableOffset FLATBUFFERS_VTABLE_UNDERLYING_TYPE {
     VT_OBJECTS = 4,
     VT_ENUMS = 6,
@@ -1072,6 +1105,7 @@
 };
 
 struct SchemaBuilder {
+  typedef Schema Table;
   flatbuffers::FlatBufferBuilder &fbb_;
   flatbuffers::uoffset_t start_;
   void add_objects(flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<reflection::Object>>> objects) {
@@ -1096,7 +1130,6 @@
         : fbb_(_fbb) {
     start_ = fbb_.StartTable();
   }
-  SchemaBuilder &operator=(const SchemaBuilder &);
   flatbuffers::Offset<Schema> Finish() {
     const auto end = fbb_.EndTable(start_);
     auto o = flatbuffers::Offset<Schema>(end);
@@ -1126,17 +1159,17 @@
 
 inline flatbuffers::Offset<Schema> CreateSchemaDirect(
     flatbuffers::FlatBufferBuilder &_fbb,
-    const std::vector<flatbuffers::Offset<reflection::Object>> *objects = nullptr,
-    const std::vector<flatbuffers::Offset<reflection::Enum>> *enums = nullptr,
+    std::vector<flatbuffers::Offset<reflection::Object>> *objects = nullptr,
+    std::vector<flatbuffers::Offset<reflection::Enum>> *enums = nullptr,
     const char *file_ident = nullptr,
     const char *file_ext = nullptr,
     flatbuffers::Offset<reflection::Object> root_table = 0,
-    const std::vector<flatbuffers::Offset<reflection::Service>> *services = nullptr) {
-  auto objects__ = objects ? _fbb.CreateVector<flatbuffers::Offset<reflection::Object>>(*objects) : 0;
-  auto enums__ = enums ? _fbb.CreateVector<flatbuffers::Offset<reflection::Enum>>(*enums) : 0;
+    std::vector<flatbuffers::Offset<reflection::Service>> *services = nullptr) {
+  auto objects__ = objects ? _fbb.CreateVectorOfSortedTables<reflection::Object>(objects) : 0;
+  auto enums__ = enums ? _fbb.CreateVectorOfSortedTables<reflection::Enum>(enums) : 0;
   auto file_ident__ = file_ident ? _fbb.CreateString(file_ident) : 0;
   auto file_ext__ = file_ext ? _fbb.CreateString(file_ext) : 0;
-  auto services__ = services ? _fbb.CreateVector<flatbuffers::Offset<reflection::Service>>(*services) : 0;
+  auto services__ = services ? _fbb.CreateVectorOfSortedTables<reflection::Service>(services) : 0;
   return reflection::CreateSchema(
       _fbb,
       objects__,
diff --git a/include/flatbuffers/stl_emulation.h b/include/flatbuffers/stl_emulation.h
index 6f6e766..66bd620 100644
--- a/include/flatbuffers/stl_emulation.h
+++ b/include/flatbuffers/stl_emulation.h
@@ -18,6 +18,7 @@
 #define FLATBUFFERS_STL_EMULATION_H_
 
 // clang-format off
+#include "flatbuffers/base.h"
 
 #include <string>
 #include <type_traits>
@@ -33,15 +34,34 @@
   #include <cctype>
 #endif  // defined(FLATBUFFERS_CPP98_STL)
 
-// Check if we can use template aliases
-// Not possible if Microsoft Compiler before 2012
-// Possible is the language feature __cpp_alias_templates is defined well
-// Or possible if the C++ std is C+11 or newer
-#if (defined(_MSC_VER) && _MSC_VER > 1700 /* MSVC2012 */) \
-    || (defined(__cpp_alias_templates) && __cpp_alias_templates >= 200704) \
-    || (defined(__cplusplus) && __cplusplus >= 201103L)
-  #define FLATBUFFERS_TEMPLATES_ALIASES
-#endif
+// Detect C++17 compatible compiler.
+// __cplusplus >= 201703L - a compiler has support of 'static inline' variables.
+#if defined(FLATBUFFERS_USE_STD_OPTIONAL) \
+    || (defined(__cplusplus) && __cplusplus >= 201703L) \
+    || (defined(_MSVC_LANG) &&  (_MSVC_LANG >= 201703L))
+  #include <optional>
+  #ifndef FLATBUFFERS_USE_STD_OPTIONAL
+    #define FLATBUFFERS_USE_STD_OPTIONAL
+  #endif
+#endif // defined(FLATBUFFERS_USE_STD_OPTIONAL) ...
+
+// The __cpp_lib_span is the predefined feature macro.
+#if defined(FLATBUFFERS_USE_STD_SPAN)
+    #include <span>
+#elif defined(__cpp_lib_span) && defined(__has_include)
+  #if __has_include(<span>)
+    #include <span>
+    #define FLATBUFFERS_USE_STD_SPAN
+  #endif
+#else
+  // Disable non-trivial ctors if FLATBUFFERS_SPAN_MINIMAL defined.
+  #if !defined(FLATBUFFERS_TEMPLATES_ALIASES) || defined(FLATBUFFERS_CPP98_STL)
+    #define FLATBUFFERS_SPAN_MINIMAL
+  #else
+    // Enable implicit construction of a span<T,N> from a std::array<T,N>.
+    #include <array>
+  #endif
+#endif // defined(FLATBUFFERS_USE_STD_SPAN)
 
 // This header provides backwards compatibility for C++98 STLs like stlport.
 namespace flatbuffers {
@@ -96,13 +116,13 @@
       }
   };
 
-  template <> class numeric_limits<float> : 
+  template <> class numeric_limits<float> :
       public std::numeric_limits<float> {
     public:
       static float lowest() { return -FLT_MAX; }
   };
 
-  template <> class numeric_limits<double> : 
+  template <> class numeric_limits<double> :
       public std::numeric_limits<double> {
     public:
       static double lowest() { return -DBL_MAX; }
@@ -138,7 +158,12 @@
     template <typename T, typename U> using is_same = std::is_same<T,U>;
     template <typename T> using is_floating_point = std::is_floating_point<T>;
     template <typename T> using is_unsigned = std::is_unsigned<T>;
+    template <typename T> using is_enum = std::is_enum<T>;
     template <typename T> using make_unsigned = std::make_unsigned<T>;
+    template<bool B, class T, class F>
+    using conditional = std::conditional<B, T, F>;
+    template<class T, T v>
+    using integral_constant = std::integral_constant<T, v>;
   #else
     // Map C++ TR1 templates defined by stlport.
     template <typename T> using is_scalar = std::tr1::is_scalar<T>;
@@ -146,6 +171,7 @@
     template <typename T> using is_floating_point =
         std::tr1::is_floating_point<T>;
     template <typename T> using is_unsigned = std::tr1::is_unsigned<T>;
+    template <typename T> using is_enum = std::tr1::is_enum<T>;
     // Android NDK doesn't have std::make_unsigned or std::tr1::make_unsigned.
     template<typename T> struct make_unsigned {
       static_assert(is_unsigned<T>::value, "Specialization not implemented!");
@@ -157,6 +183,10 @@
     template<> struct make_unsigned<long> { using type = unsigned long; };
     template<>
     struct make_unsigned<long long> { using type = unsigned long long; };
+    template<bool B, class T, class F>
+    using conditional = std::tr1::conditional<B, T, F>;
+    template<class T, T v>
+    using integral_constant = std::tr1::integral_constant<T, v>;
   #endif  // !FLATBUFFERS_CPP98_STL
 #else
   // MSVC 2010 doesn't support C++11 aliases.
@@ -165,7 +195,12 @@
   template <typename T> struct is_floating_point :
         public std::is_floating_point<T> {};
   template <typename T> struct is_unsigned : public std::is_unsigned<T> {};
+  template <typename T> struct is_enum : public std::is_enum<T> {};
   template <typename T> struct make_unsigned : public std::make_unsigned<T> {};
+  template<bool B, class T, class F>
+  struct conditional : public std::conditional<B, T, F> {};
+  template<class T, T v>
+  struct integral_constant : public std::integral_constant<T, v> {};
 #endif  // defined(FLATBUFFERS_TEMPLATES_ALIASES)
 
 #ifndef FLATBUFFERS_CPP98_STL
@@ -175,7 +210,7 @@
     // MSVC 2010 doesn't support C++11 aliases.
     // We're manually "aliasing" the class here as we want to bring unique_ptr
     // into the flatbuffers namespace.  We have unique_ptr in the flatbuffers
-    // namespace we have a completely independent implemenation (see below)
+    // namespace we have a completely independent implementation (see below)
     // for C++98 STL implementations.
     template <class T> class unique_ptr : public std::unique_ptr<T> {
      public:
@@ -268,8 +303,365 @@
   template <class T> bool operator==(const unique_ptr<T>& x, intptr_t y) {
     return reinterpret_cast<intptr_t>(x.get()) == y;
   }
+
+  template <class T> bool operator!=(const unique_ptr<T>& x, decltype(nullptr)) {
+    return !!x;
+  }
+
+  template <class T> bool operator!=(decltype(nullptr), const unique_ptr<T>& x) {
+    return !!x;
+  }
+
+  template <class T> bool operator==(const unique_ptr<T>& x, decltype(nullptr)) {
+    return !x;
+  }
+
+  template <class T> bool operator==(decltype(nullptr), const unique_ptr<T>& x) {
+    return !x;
+  }
+
 #endif  // !FLATBUFFERS_CPP98_STL
 
+#ifdef FLATBUFFERS_USE_STD_OPTIONAL
+template<class T>
+using Optional = std::optional<T>;
+using nullopt_t = std::nullopt_t;
+inline constexpr nullopt_t nullopt = std::nullopt;
+
+#else
+// Limited implementation of Optional<T> type for a scalar T.
+// This implementation limited by trivial types compatible with
+// std::is_arithmetic<T> or std::is_enum<T> type traits.
+
+// A tag to indicate an empty flatbuffers::optional<T>.
+struct nullopt_t {
+  explicit FLATBUFFERS_CONSTEXPR_CPP11 nullopt_t(int) {}
+};
+
+#if defined(FLATBUFFERS_CONSTEXPR_DEFINED)
+  namespace internal {
+    template <class> struct nullopt_holder {
+      static constexpr nullopt_t instance_ = nullopt_t(0);
+    };
+    template<class Dummy>
+    constexpr nullopt_t nullopt_holder<Dummy>::instance_;
+  }
+  static constexpr const nullopt_t &nullopt = internal::nullopt_holder<void>::instance_;
+
+#else
+  namespace internal {
+    template <class> struct nullopt_holder {
+      static const nullopt_t instance_;
+    };
+    template<class Dummy>
+    const nullopt_t nullopt_holder<Dummy>::instance_  = nullopt_t(0);
+  }
+  static const nullopt_t &nullopt = internal::nullopt_holder<void>::instance_;
+
+#endif
+
+template<class T>
+class Optional FLATBUFFERS_FINAL_CLASS {
+  // Non-scalar 'T' would extremely complicated Optional<T>.
+  // Use is_scalar<T> checking because flatbuffers flatbuffers::is_arithmetic<T>
+  // isn't implemented.
+  static_assert(flatbuffers::is_scalar<T>::value, "unexpected type T");
+
+ public:
+  ~Optional() {}
+
+  FLATBUFFERS_CONSTEXPR_CPP11 Optional() FLATBUFFERS_NOEXCEPT
+    : value_(), has_value_(false) {}
+
+  FLATBUFFERS_CONSTEXPR_CPP11 Optional(nullopt_t) FLATBUFFERS_NOEXCEPT
+    : value_(), has_value_(false) {}
+
+  FLATBUFFERS_CONSTEXPR_CPP11 Optional(T val) FLATBUFFERS_NOEXCEPT
+    : value_(val), has_value_(true) {}
+
+  FLATBUFFERS_CONSTEXPR_CPP11 Optional(const Optional &other) FLATBUFFERS_NOEXCEPT
+    : value_(other.value_), has_value_(other.has_value_) {}
+
+  FLATBUFFERS_CONSTEXPR_CPP14 Optional &operator=(const Optional &other) FLATBUFFERS_NOEXCEPT {
+    value_ = other.value_;
+    has_value_ = other.has_value_;
+    return *this;
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP14 Optional &operator=(nullopt_t) FLATBUFFERS_NOEXCEPT {
+    value_ = T();
+    has_value_ = false;
+    return *this;
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP14 Optional &operator=(T val) FLATBUFFERS_NOEXCEPT {
+    value_ = val;
+    has_value_ = true;
+    return *this;
+  }
+
+  void reset() FLATBUFFERS_NOEXCEPT {
+    *this = nullopt;
+  }
+
+  void swap(Optional &other) FLATBUFFERS_NOEXCEPT {
+    std::swap(value_, other.value_);
+    std::swap(has_value_, other.has_value_);
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP11 FLATBUFFERS_EXPLICIT_CPP11 operator bool() const FLATBUFFERS_NOEXCEPT {
+    return has_value_;
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP11 bool has_value() const FLATBUFFERS_NOEXCEPT {
+    return has_value_;
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP11 const T& operator*() const FLATBUFFERS_NOEXCEPT {
+    return value_;
+  }
+
+  const T& value() const {
+    FLATBUFFERS_ASSERT(has_value());
+    return value_;
+  }
+
+  T value_or(T default_value) const FLATBUFFERS_NOEXCEPT {
+    return has_value() ? value_ : default_value;
+  }
+
+ private:
+  T value_;
+  bool has_value_;
+};
+
+template<class T>
+FLATBUFFERS_CONSTEXPR_CPP11 bool operator==(const Optional<T>& opt, nullopt_t) FLATBUFFERS_NOEXCEPT {
+  return !opt;
+}
+template<class T>
+FLATBUFFERS_CONSTEXPR_CPP11 bool operator==(nullopt_t, const Optional<T>& opt) FLATBUFFERS_NOEXCEPT {
+  return !opt;
+}
+
+template<class T, class U>
+FLATBUFFERS_CONSTEXPR_CPP11 bool operator==(const Optional<T>& lhs, const U& rhs) FLATBUFFERS_NOEXCEPT {
+  return static_cast<bool>(lhs) && (*lhs == rhs);
+}
+
+template<class T, class U>
+FLATBUFFERS_CONSTEXPR_CPP11 bool operator==(const T& lhs, const Optional<U>& rhs) FLATBUFFERS_NOEXCEPT {
+  return static_cast<bool>(rhs) && (lhs == *rhs);
+}
+
+template<class T, class U>
+FLATBUFFERS_CONSTEXPR_CPP11 bool operator==(const Optional<T>& lhs, const Optional<U>& rhs) FLATBUFFERS_NOEXCEPT {
+  return static_cast<bool>(lhs) != static_cast<bool>(rhs)
+              ? false
+              : !static_cast<bool>(lhs) ? false : (*lhs == *rhs);
+}
+#endif // FLATBUFFERS_USE_STD_OPTIONAL
+
+
+// Very limited and naive partial implementation of C++20 std::span<T,Extent>.
+#if defined(FLATBUFFERS_USE_STD_SPAN)
+  inline constexpr std::size_t dynamic_extent = std::dynamic_extent;
+  template<class T, std::size_t Extent = std::dynamic_extent>
+  using span = std::span<T, Extent>;
+
+#else // !defined(FLATBUFFERS_USE_STD_SPAN)
+FLATBUFFERS_CONSTEXPR std::size_t dynamic_extent = static_cast<std::size_t>(-1);
+
+// Exclude this code if MSVC2010 or non-STL Android is active.
+// The non-STL Android doesn't have `std::is_convertible` required for SFINAE.
+#if !defined(FLATBUFFERS_SPAN_MINIMAL)
+namespace internal {
+  // This is SFINAE helper class for checking of a common condition:
+  // > This overload only participates in overload resolution
+  // > Check whether a pointer to an array of U can be converted
+  // > to a pointer to an array of E.
+  // This helper is used for checking of 'U -> const U'.
+  template<class E, std::size_t Extent, class U, std::size_t N>
+  struct is_span_convertable {
+    using type =
+      typename std::conditional<std::is_convertible<U (*)[], E (*)[]>::value
+                                && (Extent == dynamic_extent || N == Extent),
+                                int, void>::type;
+  };
+
+}  // namespace internal
+#endif  // !defined(FLATBUFFERS_SPAN_MINIMAL)
+
+// T - element type; must be a complete type that is not an abstract
+// class type.
+// Extent - the number of elements in the sequence, or dynamic.
+template<class T, std::size_t Extent = dynamic_extent>
+class span FLATBUFFERS_FINAL_CLASS {
+ public:
+  typedef T element_type;
+  typedef T& reference;
+  typedef const T& const_reference;
+  typedef T* pointer;
+  typedef const T* const_pointer;
+  typedef std::size_t size_type;
+
+  static FLATBUFFERS_CONSTEXPR size_type extent = Extent;
+
+  // Returns the number of elements in the span.
+  FLATBUFFERS_CONSTEXPR_CPP11 size_type size() const FLATBUFFERS_NOEXCEPT {
+    return count_;
+  }
+
+  // Returns the size of the sequence in bytes.
+  FLATBUFFERS_CONSTEXPR_CPP11
+  size_type size_bytes() const FLATBUFFERS_NOEXCEPT {
+    return size() * sizeof(element_type);
+  }
+
+  // Checks if the span is empty.
+  FLATBUFFERS_CONSTEXPR_CPP11 bool empty() const FLATBUFFERS_NOEXCEPT {
+    return size() == 0;
+  }
+
+  // Returns a pointer to the beginning of the sequence.
+  FLATBUFFERS_CONSTEXPR_CPP11 pointer data() const FLATBUFFERS_NOEXCEPT {
+    return data_;
+  }
+
+  // Returns a reference to the idx-th element of the sequence.
+  // The behavior is undefined if the idx is greater than or equal to size().
+  FLATBUFFERS_CONSTEXPR_CPP11 reference operator[](size_type idx) const {
+    return data()[idx];
+  }
+
+  FLATBUFFERS_CONSTEXPR_CPP11 span(const span &other) FLATBUFFERS_NOEXCEPT
+      : data_(other.data_), count_(other.count_) {}
+
+  FLATBUFFERS_CONSTEXPR_CPP14 span &operator=(const span &other)
+      FLATBUFFERS_NOEXCEPT {
+    data_ = other.data_;
+    count_ = other.count_;
+  }
+
+  // Limited implementation of
+  // `template <class It> constexpr std::span(It first, size_type count);`.
+  //
+  // Constructs a span that is a view over the range [first, first + count);
+  // the resulting span has: data() == first and size() == count.
+  // The behavior is undefined if [first, first + count) is not a valid range,
+  // or if (extent != flatbuffers::dynamic_extent && count != extent).
+  FLATBUFFERS_CONSTEXPR_CPP11
+  explicit span(pointer first, size_type count) FLATBUFFERS_NOEXCEPT
+    : data_ (Extent == dynamic_extent ? first : (Extent == count ? first : nullptr)),
+      count_(Extent == dynamic_extent ? count : (Extent == count ? Extent : 0)) {
+      // Make span empty if the count argument is incompatible with span<T,N>.
+  }
+
+  // Exclude this code if MSVC2010 is active. The MSVC2010 isn't C++11
+  // compliant, it doesn't support default template arguments for functions.
+  #if defined(FLATBUFFERS_SPAN_MINIMAL)
+  FLATBUFFERS_CONSTEXPR_CPP11 span() FLATBUFFERS_NOEXCEPT : data_(nullptr),
+                                                            count_(0) {
+    static_assert(extent == 0 || extent == dynamic_extent, "invalid span");
+  }
+
+  #else
+  // Constructs an empty span whose data() == nullptr and size() == 0.
+  // This overload only participates in overload resolution if
+  // extent == 0 || extent == flatbuffers::dynamic_extent.
+  // A dummy template argument N is need dependency for SFINAE.
+  template<std::size_t N = 0,
+    typename internal::is_span_convertable<element_type, Extent, element_type, (N - N)>::type = 0>
+  FLATBUFFERS_CONSTEXPR_CPP11 span() FLATBUFFERS_NOEXCEPT : data_(nullptr),
+                                                            count_(0) {
+    static_assert(extent == 0 || extent == dynamic_extent, "invalid span");
+  }
+
+  // Constructs a span that is a view over the array arr; the resulting span
+  // has size() == N and data() == std::data(arr). These overloads only
+  // participate in overload resolution if
+  // extent == std::dynamic_extent || N == extent is true and
+  // std::remove_pointer_t<decltype(std::data(arr))>(*)[]
+  // is convertible to element_type (*)[].
+  template<std::size_t N,
+    typename internal::is_span_convertable<element_type, Extent, element_type, N>::type = 0>
+  FLATBUFFERS_CONSTEXPR_CPP11 span(element_type (&arr)[N]) FLATBUFFERS_NOEXCEPT
+      : data_(arr), count_(N) {}
+
+  template<class U, std::size_t N,
+    typename internal::is_span_convertable<element_type, Extent, U, N>::type = 0>
+  FLATBUFFERS_CONSTEXPR_CPP11 span(std::array<U, N> &arr) FLATBUFFERS_NOEXCEPT
+     : data_(arr.data()), count_(N) {}
+
+  //template<class U, std::size_t N,
+  //  int = 0>
+  //FLATBUFFERS_CONSTEXPR_CPP11 span(std::array<U, N> &arr) FLATBUFFERS_NOEXCEPT
+  //   : data_(arr.data()), count_(N) {}
+
+  template<class U, std::size_t N,
+    typename internal::is_span_convertable<element_type, Extent, U, N>::type = 0>
+  FLATBUFFERS_CONSTEXPR_CPP11 span(const std::array<U, N> &arr) FLATBUFFERS_NOEXCEPT
+    : data_(arr.data()), count_(N) {}
+
+  // Converting constructor from another span s;
+  // the resulting span has size() == s.size() and data() == s.data().
+  // This overload only participates in overload resolution
+  // if extent == std::dynamic_extent || N == extent is true and U (*)[]
+  // is convertible to element_type (*)[].
+  template<class U, std::size_t N,
+    typename internal::is_span_convertable<element_type, Extent, U, N>::type = 0>
+  FLATBUFFERS_CONSTEXPR_CPP11 span(const flatbuffers::span<U, N> &s) FLATBUFFERS_NOEXCEPT
+      : span(s.data(), s.size()) {
+  }
+
+  #endif  // !defined(FLATBUFFERS_SPAN_MINIMAL)
+
+ private:
+  // This is a naive implementation with 'count_' member even if (Extent != dynamic_extent).
+  pointer const data_;
+  const size_type count_;
+};
+
+ #if !defined(FLATBUFFERS_SPAN_MINIMAL)
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<U, N> make_span(U(&arr)[N]) FLATBUFFERS_NOEXCEPT {
+    return span<U, N>(arr);
+  }
+
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<const U, N> make_span(const U(&arr)[N]) FLATBUFFERS_NOEXCEPT {
+    return span<const U, N>(arr);
+  }
+
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<U, N> make_span(std::array<U, N> &arr) FLATBUFFERS_NOEXCEPT {
+    return span<U, N>(arr);
+  }
+
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<const U, N> make_span(const std::array<U, N> &arr) FLATBUFFERS_NOEXCEPT {
+    return span<const U, N>(arr);
+  }
+
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<U, dynamic_extent> make_span(U *first, std::size_t count) FLATBUFFERS_NOEXCEPT {
+    return span<U, dynamic_extent>(first, count);
+  }
+
+  template<class U, std::size_t N>
+  FLATBUFFERS_CONSTEXPR_CPP11
+  flatbuffers::span<const U, dynamic_extent> make_span(const U *first, std::size_t count) FLATBUFFERS_NOEXCEPT {
+    return span<const U, dynamic_extent>(first, count);
+  }
+#endif
+
+#endif  // defined(FLATBUFFERS_USE_STD_SPAN)
+
 }  // namespace flatbuffers
 
 #endif  // FLATBUFFERS_STL_EMULATION_H_
diff --git a/include/flatbuffers/util.h b/include/flatbuffers/util.h
index 072fe9e..2aafa48 100644
--- a/include/flatbuffers/util.h
+++ b/include/flatbuffers/util.h
@@ -17,10 +17,11 @@
 #ifndef FLATBUFFERS_UTIL_H_
 #define FLATBUFFERS_UTIL_H_
 
-#include "flatbuffers/base.h"
-
 #include <errno.h>
 
+#include "flatbuffers/base.h"
+#include "flatbuffers/stl_emulation.h"
+
 #ifndef FLATBUFFERS_PREFER_PRINTF
 #  include <sstream>
 #else  // FLATBUFFERS_PREFER_PRINTF
@@ -72,6 +73,14 @@
 // Case-insensitive isalnum
 inline bool is_alnum(char c) { return is_alpha(c) || is_digit(c); }
 
+inline char CharToUpper(char c) {
+  return static_cast<char>(::toupper(static_cast<unsigned char>(c)));
+}
+
+inline char CharToLower(char c) {
+  return static_cast<char>(::tolower(static_cast<unsigned char>(c)));
+}
+
 // @end-locale-independent functions for ASCII character set
 
 #ifdef FLATBUFFERS_PREFER_PRINTF
@@ -446,7 +455,7 @@
 // Strip the last component of the path + separator.
 std::string StripFileName(const std::string &filepath);
 
-// Concatenates a path with a filename, regardless of wether the path
+// Concatenates a path with a filename, regardless of whether the path
 // ends in a separator or not.
 std::string ConCatPathFileName(const std::string &path,
                                const std::string &filename);
@@ -636,6 +645,32 @@
   return true;
 }
 
+inline std::string BufferToHexText(const void *buffer, size_t buffer_size,
+                                   size_t max_length,
+                                   const std::string &wrapped_line_prefix,
+                                   const std::string &wrapped_line_suffix) {
+  std::string text = wrapped_line_prefix;
+  size_t start_offset = 0;
+  const char *s = reinterpret_cast<const char *>(buffer);
+  for (size_t i = 0; s && i < buffer_size; i++) {
+    // Last iteration or do we have more?
+    bool have_more = i + 1 < buffer_size;
+    text += "0x";
+    text += IntToStringHex(static_cast<uint8_t>(s[i]), 2);
+    if (have_more) { text += ','; }
+    // If we have more to process and we reached max_length
+    if (have_more &&
+        text.size() + wrapped_line_suffix.size() >= start_offset + max_length) {
+      text += wrapped_line_suffix;
+      text += '\n';
+      start_offset = text.size();
+      text += wrapped_line_prefix;
+    }
+  }
+  text += wrapped_line_suffix;
+  return text;
+}
+
 // Remove paired quotes in a string: "text"|'text' -> text.
 std::string RemoveStringQuotes(const std::string &s);