tree 271cfd2b7de7d1702c4894a28fd81e3541b49320
parent b3960a7de0a594305efe96fc6431a2581b8a5520
author Joe Tsai <joetsai@digital-static.net> 1543992836 -0800
committer Joe Tsai <thebrokentoaster@gmail.com> 1544118447 +0000

cmd/protoc-gen-go: generate descriptor and plugin with reflection

In CL/152020, we checked in pre-generated versions of descriptor and plugin.
This CL makes it such that they are generated by protoc-gen-go.

We modify protoc-gen-go to avoid reflection support by default
since the binary size increase is still an issue to investigate.
Reflection support is temporarily enabled by setting a special
PROTOC_GEN_GO_ENABLE_REFLECT environment variable.

Reflection support is always enabled for descriptor and plugin.
Furthermore, we change descriptor to depend on the protoapi package
instead of the proto package. The reason we do not switch to protoapi
for all generated protos is because we still depend on v1 proto
for the table-driven InternalMessageInfo type. Dropping it from descriptor
is semantically correct, but does incur slight performance cost.
It does not seem appropriate to drop it for all generated messages.

We could move InternalMessageInfo to protoapi, but the logic behind that
is significant.

Change-Id: I5c3fff7f6eab1a5a2399049d42fa6bf42d4c93f9
Reviewed-on: https://go-review.googlesource.com/c/152547
Reviewed-by: Damien Neil <dneil@google.com>