Change-Id: I1dab6caf66b989075199944ce8d07fe8e5e4573a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/643957
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Chressie Himpel <chressie@google.com>

Weak fields were the predecessor to extensions (many many years ago) and were
entirely removed from Google’s production usage by now. (The corresponding field
in descriptor.proto was always documented as “// For Google-internal migration
only. Do not use.”)

Before this change, Go Protobuf still contained support for weak fields behind
the `protolegacy` build tag.

The `protolegacy` build tag was always documented as not being part of the
compatibility agreement:

// WARNING: The compatibility agreement covers nothing provided by this flag.
// As such, functionality may suddenly be removed or changed at our discretion.
const ProtoLegacy = protoLegacy

Fixes golang/protobuf#1666

Change-Id: Ie1675424bc80d9f44345ccb96a858ef847ee1018
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/641655
Reviewed-by: Chressie Himpel <chressie@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

This turns the nameclash testprotos ending in 3 into .proto
files which use syntax = "proto3". Prior to the Opaque API release,
we changed these .proto files to use editions, but using editions
with proto3 semantics is not exactly the same as using proto3,
so we need these .proto files to use syntax = "proto3";

Fixes golang/protobuf#1675

Change-Id: I0ebb37d4e1bf0fc830bbe613148429ec6ff5c46d
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/644437
Reviewed-by: Chressie Himpel <chressie@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

Change-Id: Ibc6071607a8e1afbd77b8aceeab017c0a0a7e3f9
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/647155
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Chressie Himpel <chressie@google.com>