flatten the instruction dispatch loop

crates/to-syn-value_derive/src/lib.rs

@@ -0,0 +1,20 @@
+use syn::*;
+use quote::*;
+
+#[proc_macro_derive(ToDeriveInput)]
+pub fn derive_to_derive_input(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let derive_input = parse_macro_input!(input as DeriveInput);
+    let ty_name = derive_input.ident.clone();
+
+    quote! {
+        use to_syn_value::*;
+
+        impl ToDeriveInput for #ty_name {
+            fn to_derive_input() -> syn::DeriveInput {
+                syn::parse_quote! {
+                    #derive_input
+                }
+            }
+        }
+    }.into()
+}