simplify some other generics

library/proc_macro/src/bridge/mod.rs

@@ -173,7 +173,7 @@ impl<T, M> Mark for Marked<T, M> {
         self.value
     }
 }
-impl<'a, T, M> Mark for &'a Marked<T, M> {
+impl<'a, T> Mark for &'a Marked<T, client::TokenStream> {
     type Unmarked = &'a T;
     fn mark(_: Self::Unmarked) -> Self {
         unreachable!()
@@ -220,6 +220,8 @@ mark_noop! {
     Delimiter,
     LitKind,
     Level,
+    Bound<usize>,
+    Range<usize>,
 }
 
 rpc_encode_decode!(
@@ -318,7 +320,7 @@ macro_rules! compound_traits {
     };
 }
 
-compound_traits!(
+rpc_encode_decode!(
     enum Bound<T> {
         Included(x),
         Excluded(x),
@@ -390,7 +392,7 @@ pub struct Literal<Span, Symbol> {
     pub span: Span,
 }
 
-compound_traits!(struct Literal<Sp, Sy> { kind, symbol, suffix, span });
+compound_traits!(struct Literal<Span, Symbol> { kind, symbol, suffix, span });
 
 #[derive(Clone)]
 pub enum TokenTree<TokenStream, Span, Symbol> {
@@ -434,6 +436,6 @@ compound_traits!(
     struct ExpnGlobals<Span> { def_site, call_site, mixed_site }
 );
 
-compound_traits!(
+rpc_encode_decode!(
     struct Range<T> { start, end }
 );

library/proc_macro/src/bridge/server.rs

@@ -63,7 +63,7 @@ macro_rules! define_server_dispatcher_impl {
         $(fn $method:ident($($arg:ident: $arg_ty:ty),* $(,)?) $(-> $ret_ty:ty)*;)*
     ) => {
         pub trait Server {
-            type TokenStream: 'static + Clone;
+            type TokenStream: 'static + Clone + Default;
             type Span: 'static + Copy + Eq + Hash;
             type Symbol: 'static;
 
@@ -312,7 +312,6 @@ impl client::Client<crate::TokenStream, crate::TokenStream> {
     ) -> Result<S::TokenStream, PanicMessage>
     where
         S: Server,
-        S::TokenStream: Default,
     {
         let client::Client { handle_counters, run, _marker } = *self;
         run_server(
@@ -338,7 +337,6 @@ impl client::Client<(crate::TokenStream, crate::TokenStream), crate::TokenStream
     ) -> Result<S::TokenStream, PanicMessage>
     where
         S: Server,
-        S::TokenStream: Default,
     {
         let client::Client { handle_counters, run, _marker } = *self;
         run_server(