While odd, it is possible to merge a message into itself.
In such a situation, the material impact is that repeated
and unknown fields are duplicated. The previous logic would
inifinite loop since the list iteration logic uses the current
length, but since the current length is ever growing, this loop
will never terminate. Instead, record the list length once
and iterate exactly that many times.
Change-Id: Ief98afa1b20bd950a9c2422d4462b170dbe6fa11
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/196857
Reviewed-by: Damien Neil <dneil@google.com>
Some existing targets (whether correctly or not) rely on it Merge
being safe to call concurrently so long as the set of fields being
merged are disjoint.
Change-Id: I4db9e64efccc7a2d44a5f9b52261b611cce461b0
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/196737
Reviewed-by: Damien Neil <dneil@google.com>
