fix 2020: return None if the root nodes are empty in rsx (#2026)

packages/rsx/src/lib.rs

@@ -84,10 +84,13 @@ impl CallBody {
             location: Some(location),
         };
 
+        // Empty templates just are placeholders for "none"
+        if self.roots.is_empty() {
+            return quote! { None };
+        }
+
         quote! {
-            Some({
-                #body
-            })
+            Some({ #body })
         }
     }
 }
@@ -110,20 +113,20 @@ impl Parse for CallBody {
     }
 }
 
-#[derive(Default, Debug)]
-pub struct RenderCallBody(pub CallBody);
-
-impl ToTokens for RenderCallBody {
+impl ToTokens for CallBody {
     fn to_tokens(&self, out_tokens: &mut TokenStream2) {
         let body: TemplateRenderer = TemplateRenderer {
-            roots: &self.0.roots,
+            roots: &self.roots,
             location: None,
         };
 
+        // Empty templates just are placeholders for "none"
+        if self.roots.is_empty() {
+            return out_tokens.append_all(quote! { None });
+        }
+
         out_tokens.append_all(quote! {
-            Some({
-                #body
-            })
+            Some({ #body })
         })
     }
 }
@@ -145,6 +148,7 @@ impl<'a> TemplateRenderer<'a> {
         let mut context = DynamicContext::default();
 
         let mut roots = Vec::new();
+
         for (idx, root) in self.roots.iter().enumerate() {
             context.current_path.push(idx as u8);
             roots.push(context.update_node::<Ctx>(root, &mut mapping)?);