rpc: Make rpc::Client and SubscriptionClient traits ?Send under…

… `wasm32` target (informalsystems#1386)

* made rpc::Client and SubscriptionClient traits conditionally ?Send

* updated changelog

CHANGELOG.md

@@ -39,6 +39,8 @@ Support for Secp256k1 consensus keys has been added as an optional feature.
 - `[tendermint-rpc]` Turn non-200 HTTP response into an error
   instead of trying to parse the body as a JSON-RPC response
   ([\#1359](https://github.com/informalsystems/tendermint-rs/issues/1359))
+- `[tendermint-rpc]` Make `rpc::Client` and `SubscriptionClient` traits `?Send` under `wasm32` target.
+  ([\#1385](https://github.com/informalsystems/tendermint-rs/issues/1385))
 
 ### SECURITY
 

rpc/src/client.rs

@@ -45,7 +45,8 @@ use crate::{
 /// [`SubscriptionClient`] trait.
 ///
 /// [`SubscriptionClient`]: trait.SubscriptionClient.html
-#[async_trait]
+#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 pub trait Client {
     /// `/abci_info`: get information about the ABCI application.
     async fn abci_info(&self) -> Result<abci::response::Info, Error> {

rpc/src/client/subscription.rs

@@ -19,7 +19,8 @@ use crate::{
 
 /// A client that exclusively provides [`Event`] subscription capabilities,
 /// without any other RPC method support.
-#[async_trait]
+#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
 pub trait SubscriptionClient {
     /// `/subscribe`: subscribe to receive events produced by the given query.
     async fn subscribe(&self, query: Query) -> Result<Subscription, Error>;