all: do best-effort initialization check on fast path unmarshal

Add a fast check for required fields to the fast path unmarshal.
This is best-effort and will fail to detect some initialized
messages: Messages with more than 64 required fields, messages
split across multiple tags, possibly other cases.

In the cases where it works (which is most of them in practice),
this permits us to skip the IsInitialized check.

Change-Id: I6b70953a333033a5e64fb7ca37a59786cb0f75a0
Reviewed-by: Joe Tsai <>
7 files changed
tree: 79176c74512f4fdbc74194dd5918a659c11b3416
  1. .gitignore
  2. .travis.yml
  9. cmd/
  10. compiler/
  11. encoding/
  12. go.mod
  13. go.sum
  14. integration_test.go
  15. internal/
  16. proto/
  17. reflect/
  18. regenerate.bash
  19. release.bash
  20. runtime/
  21. test.bash
  22. testing/
  23. types/

Next Generation Go Protocol Buffers

WARNING: This repository is in active development. There are no guarantees about API stability. Breaking changes will occur until a stable release is made and announced.

This repository is for the development of the next major Go implementation of protocol buffers. This library makes breaking API changes relative to the existing Go protobuf library. Of particular note, this API aims to make protobuf reflection a first-class feature of the API and implements the protobuf ecosystem in terms of reflection.

Design Documents

List of relevant design documents:


We appreciate community contributions. See

Reporting Issues

Issues regarding the new API can be filed at Please use a APIv2: prefix in the title to make it clear that the issue is regarding the new API work.