proto: reset message by default in Unmarshal
We change Unmarshal to reset a message by default.
* We add a Merge option to UnmarshalOptions for explicit merging.
* We speed up Reset by checking for the Reset method.
* Remove TODOs in prototext and protojson about reset behavior.
Fixes golang/protobuf#890
Change-Id: Ibd8963c741053f564acf061fbdb846699942109c
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/195457
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/runtime/protoiface/methods.go b/runtime/protoiface/methods.go
index 5984a26..e0adf9d 100644
--- a/runtime/protoiface/methods.go
+++ b/runtime/protoiface/methods.go
@@ -73,6 +73,7 @@
type UnmarshalOptions struct {
pragma.NoUnkeyedLiterals
+ Merge bool // must be treated as true by method implementations
AllowPartial bool // must be treated as true by method implementations
DiscardUnknown bool
Resolver interface {