reflect/prototype: use proto2 syntax for standalone extension fields

Without resolving the question of whether an extension field is always proto2
or sometimes proto3, just make it impossible to construct a standalone extension
field of the proto3 syntax.

By dropping the syntax field from the constructor, we can just assume that the
syntax is always proto2. There is no benefit for creating a proto3 standalone
extension, so there is no loss of functionality.

In the unlikely future where there needs to be distinction, we can add the field
back into the descriptor. The zero value of protoreflect.Syntax is invalid,
so we can determine if the user did not set that field.

Change-Id: Ie93fa55de96f29553fb04ff6649bbea79a144407
Reviewed-on: https://go-review.googlesource.com/c/144279
Reviewed-by: Damien Neil <dneil@google.com>
2 files changed
tree: fcf760a8b64bc73a1dbd62b998c8c067458bf76e
  1. cmd/
  2. internal/
  3. protogen/
  4. reflect/
  5. .gitignore
  6. .travis.yml
  7. AUTHORS
  8. CONTRIBUTING.md
  9. CONTRIBUTORS
  10. go.mod
  11. go.sum
  12. LICENSE
  13. PATENTS
  14. README.md
  15. regenerate.bash
  16. test.bash
README.md

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:

Contributing

We appreciate community contributions. See CONTRIBUTING.md.

Reporting Issues

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