internal/weakdeps: put APIv1 weak dependency behind a build constraint

By using a build constraint that is never satisfied, we can add a weak
dependency on a module. If the module is part of a build, our go.mod
enforces a minimum version on it, but we never add it to the build
dependencies ourselves.

This is the same trick used for tool dependencies:

Dropped the TODO to remove the APIv1 dependency, since I think this
removes any need to do so.

Change-Id: I45b1a3f45535bcdc9abf34fb562d2869f1712bb6
Reviewed-by: Joe Tsai <>
3 files changed
tree: 165a1d276f8b83152ed75f2f7c09442c4309b4e5
  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.