Fix derive(Deserialize) on void enum (#330)

* Fix derive(Deserialize) on void enum

* Also fix derive(Serialize) for empty enums; remove empty reducers from tests

---------

Co-authored-by: Phoebe Goldman <phoebe@goldman-tribe.org>

crates/bindings-macro/src/module.rs

@@ -342,7 +342,7 @@ pub(crate) fn derive_deserialize(ty: &SatsType<'_>) -> TokenStream {
                         type Output = __Variant;
 
                         fn variant_names(&self, names: &mut dyn #spacetimedb_lib::de::ValidNames) {
-                            names.extend([#(#variant_names,)*])
+                            names.extend::<&[&str]>(&[#(#variant_names,)*])
                         }
 
                         fn visit_tag<E: #spacetimedb_lib::de::Error>(self, __tag: u8) -> Result<Self::Output, E> {
@@ -394,7 +394,10 @@ pub(crate) fn derive_serialize(ty: &SatsType) -> TokenStream {
                     }
                 }
             });
-            quote!(match self { #(#arms)* })
+            quote!(match self {
+                #(#arms)*
+                _ => unreachable!(),
+            })
         }
     };
     quote! {

modules/sdk-test-connect-disconnect-cs/Lib.cs

@@ -29,12 +29,4 @@ public static void Init()
             new Disconnected { identity = e.Sender }.Insert();
         };
     }
-
-    [SpacetimeDB.Reducer]
-    /// Due to a bug in SATS' `derive(Desrialize)`
-    /// https://github.com/clockworklabs/SpacetimeDB/issues/325 ,
-    /// Rust module bindings fail to compile for modules which define zero reducers
-    /// (not counting init, update, connect, disconnect).
-    /// Adding this useless empty reducer causes the module bindings to compile.
-    public static void UselessEmptyReducer() {}
 }

modules/sdk-test-connect-disconnect/src/lib.rs

@@ -29,11 +29,3 @@ pub fn identity_connected(ctx: ReducerContext) {
 pub fn identity_disconnected(ctx: ReducerContext) {
     Disconnected::insert(Disconnected { identity: ctx.sender });
 }
-
-#[spacetimedb(reducer)]
-/// Due to a bug in SATS' `derive(Desrialize)`
-/// https://github.com/clockworklabs/SpacetimeDB/issues/325 ,
-/// Rust module bindings fail to compile for modules which define zero reducers
-/// (not counting init, update, connect, disconnect).
-/// Adding this useless empty reducer causes the module bindings to compile.
-pub fn useless_empty_reducer() {}