tree f23a8dc06df88584fff4a3091bc8f8b118cac34b
parent 7328839f815b06502808df5e9ad027403d8b876d
author Joe Tsai <joetsai@digital-static.net> 1565317412 -0700
committer Joe Tsai <joetsai@digital-static.net> 1565915093 +0000

internal/impl: treat a nil oneof wrapper as if it were unset

The old implementation had the behavior where a nil wrapper value:
	m := new(foopb.Message)
	m.OneofField = (*foopb.Message_OneofUint32)(nil)
was functionally equivalent to it being directly set to nil:
	m := new(foopb.Message)
	m.OneofField = nil
preserve this semantic in both the table-drive implementation
and the reflection implementation.

Change-Id: Ie44d51e044d4822e61d0e646fbc44aa8d9b90c1f
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/189559
Reviewed-by: Herbie Ong <herbie@google.com>