tree f2dbf070c5f9053fec5459933962ef34c6387cf4
parent 8cfc14f022f558728049bb7799b69309db55ce84
author Joe Tsai <joetsai@digital-static.net> 1587146933 -0700
committer Joe Tsai <joetsai@digital-static.net> 1587425956 +0000

proto: never return nil []byte from Marshal when successful

It is a sufficiently common pattern to do something like the following:
	m.Proto2BytesField, ... = proto.Marshal(m2)

where the user is relying on Marshal to never return a nil byte slice,
otherwise it subtly changes the semantics of how the generated API
handles whether a proto2 "optional bytes" fields is populated or not.

Change-Id: Ie7508dbcdcc5f3295885609a91907c6eb4f04c1e
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/228838
Reviewed-by: Damien Neil <dneil@google.com>