Len looks like it should be O(1), but the need to check for
non-zero-length repeated fields makes it at minimum O(n) where n is
the number of repeated fields. In practice, it's O(n) where n is the
number of fields altogether.
The Len function is not especially useful, easily duplicated with Range
and a counter, and can be surprisingly inefficient. Drop it.
Change-Id: I24b27433217e131e842bd18dd58475bcdf62ef97
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/183678
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Fix a bug where using Message.Range alone does not clear
memory references for empty, but allocated lists and maps.
Thus, we iterate over every known field and explicitly call Clear.
Change-Id: I9c1847d4056cf66f3199947150f3140d0783444a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/183197
Reviewed-by: Damien Neil <dneil@google.com>
