It seems like this crate requires protoc?

error: failed to run custom build command for `prost-wkt-types v0.5.0`

Caused by:
  process didn't exit successfully: `/home/runner/work/cosmos-rust/cosmos-rust/target/release/build/prost-wkt-types-d2782fb67e78a862/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at 'Could not find `protoc` installation and this build crate cannot proceed without
      this knowledge. If `protoc` is installed and this crate had trouble finding
      it, you can set the `PROTOC` environment variable with the specific path to your
      installed `protoc` binary.If you're on debian, try `apt-get install protobuf-compiler` or download it from https://github.com/protocolbuffers/protobuf/releases

As things currently stand, both tendermint-proto and cosmos-sdk-proto pregenerate all the protos so downstream users don't need protoc installed in order to be able to use the crates.

So changing this would make protoc a hard dependency where it wasn't before.

Ah my bad, I should have realized that and asked if it was okay. I actually don't see a good reason for moving to prost-wkt-types right now so I will revert that change so that we can keep pre-generating all the protos.

Oh now I remember: Because some Protobuf messages contain Any, Duration or Timestamp, we need those so-called "well-known" types to derive Serialize in order to derive Serialize for the enclosing message via pbjson. Unfortunately, prost-types does not provide such an impl.

Potential solutions I see:

• a) Use prost-wkt-types instead of prost-types and incur the cost of downstream users having to install protoc
• b) Use pbjson-types instead of prost-types
• c) Switch between prost-types and pbjson-types at compile time based on whether the serde feature is enabled or not

Would one of those be acceptable or do you see another solution?

• d) Instruct prost-build to generate Rust definitions for the google.protobuf messages (ie. those "well-known types") instead of forwarding them to prost-types or another crate and let pbjson-build derive the serde impls for those.

Do any of those have an integration with the prost::Name trait like prost_types::Any::{from_msg, to_msg} do? We use that a lot in cosmrs: https://docs.rs/prost-types/latest/prost_types/struct.Any.html#impl-Any

I suppose if we generated our own Rust definitions for the google.protobuf messages, we could add from_msg/to_msg just like prost-types does.

@romac perhaps to break this PR up into more manageable chunks, you could PR just the change to generate our own google.protobuf.* protos which can be augmented with pbjson-build serializers? (and potentially other changes to proto-build as needed)