remove capability based approach

subxt/src/blocks/block_types.rs

@@ -167,5 +167,3 @@ where
     };
     Ok(account_nonce)
 }
-
-pub struct LatestBlockHeader {}

subxt/src/client/client_capabilities.rs

@@ -1,72 +0,0 @@
-// use crate::{backend::Backend, Config};
-
-// use super::OfflineClientT;
-use crate::{Config, Error, OfflineClient, OnlineClient};
-use core::future::Future;
-
-use super::OfflineClientT;
-
-pub type FetchBlockHeader<Header> =
-    Box<dyn Future<Output = Result<Header, Error>> + Send + 'static>;
-
-/// An object-safe trait abstracting over capabilities of offline and online-clients.
-///
-/// Implemented by [`subxt::OfflineClient`], [`subxt::OnlineClient`] and [`subxt::LightClient`] the like.
-pub trait ClientCapabilities<T: Config> {
-    fn latest_block_header(&self) -> Option<FetchBlockHeader<T::Header>>
-    where
-        T::Header: Clone;
-}
-
-impl<T: Config> ClientCapabilities<T> for OfflineClient<T> {
-    fn latest_block_header(&self) -> Option<FetchBlockHeader<T::Header>>
-    where
-        T::Header: Clone,
-    {
-        None
-    }
-}
-
-impl<T: Config> ClientCapabilities<T> for OnlineClient<T> {
-    fn latest_block_header(&self) -> Option<FetchBlockHeader<T::Header>>
-    where
-        T::Header: Clone,
-    {
-        let client = self.clone();
-        Some(Box::new(async move {
-            let block = client.blocks().at_latest().await?;
-            let header: T::Header = block.header().clone();
-            Ok(header)
-        }))
-    }
-}
-
-crate::macros::cfg_unstable_light_client! {
-    use super::LightClient;
-
-    impl<T: Config> ClientCapabilities<T> for LightClient<T> {
-        fn latest_block_header(&self) -> Option<FetchBlockHeader<T::Header>>
-        where
-            T::Header: Clone,
-        {
-            let client = self.clone();
-            Some(Box::new(async move {
-                let block = client.blocks().at_latest().await?;
-                let header: T::Header = block.header().clone();
-                Ok(header)
-            }))
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::ClientCapabilities;
-    use crate::PolkadotConfig;
-    use core::panic;
-
-    fn is_object_safe(client: Box<dyn ClientCapabilities<PolkadotConfig>>) {
-        _ = client.latest_block_header();
-        unreachable!("Do not call this function, it just needs to compile.")
-    }
-}

subxt/src/client/mod.rs

@@ -8,7 +8,6 @@
 //! require network access. The [`OnlineClient`] requires network
 //! access.
 
-mod client_capabilities;
 mod offline_client;
 mod online_client;
 

subxt/src/config/extrinsic_params.rs

@@ -88,7 +88,7 @@ pub trait DefaultOrFrom<T> {
 }
 
 impl<T> DefaultOrFrom<T> for () {
-    fn default_or_from(_value: Option<&T>) -> () {}
+    fn default_or_from(_value: Option<&T>) {}
 }
 
 macro_rules! impl_default_from_tuples {
@@ -109,6 +109,7 @@ macro_rules! impl_default_from_tuples {
     }
 }
 
+// Note: these implementations are necessary for AnyOf to work properly where arbitrary tuples are the `OtherParams`.
 #[rustfmt::skip]
 const _: () = {
     impl_default_from_tuples!(A);