fix(proc macros): don't use params as name

proc-macros/src/render_client.rs

@@ -29,7 +29,7 @@ use crate::rpc_macro::{RpcDescription, RpcMethod, RpcSubscription};
 use proc_macro2::TokenStream as TokenStream2;
 use quote::{quote, quote_spanned};
 use syn::spanned::Spanned;
-use syn::{AngleBracketedGenericArguments, FnArg, Pat, PatIdent, PatType, PathArguments, TypeParam};
+use syn::{AngleBracketedGenericArguments, FnArg, Ident, Pat, PatIdent, PatType, PathArguments, TypeParam};
 
 impl RpcDescription {
 	pub(super) fn render_client(&self) -> Result<TokenStream2, syn::Error> {
@@ -163,6 +163,8 @@ impl RpcDescription {
 		let method = quote! {
 			#docs
 			#deprecated
+			#[allow(non_snake_case)]
+			#[allow(clippy::used_underscore_binding)]
 			async fn #rust_method_name(#rust_method_params) -> #returns {
 				let params = { #parameter_builder };
 				self.#called_method(#rpc_method_name, params).await
@@ -196,6 +198,8 @@ impl RpcDescription {
 
 		let method = quote! {
 			#docs
+			#[allow(non_snake_case)]
+			#[allow(clippy::used_underscore_binding)]
 			async fn #rust_method_name(#rust_method_params) -> #returns {
 				let params = #parameter_builder;
 				self.subscribe(#rpc_sub_name, params, #rpc_unsub_name).await
@@ -210,14 +214,23 @@ impl RpcDescription {
 		param_kind: &ParamKind,
 		signature: &syn::TraitItemFn,
 	) -> TokenStream2 {
+		const ILLEGAL_PARAM_NAME: &str = "__RpcParams__";
+
 		let jsonrpsee = self.jsonrpsee_client_path.as_ref().unwrap();
+		let p = Ident::new(ILLEGAL_PARAM_NAME, proc_macro2::Span::call_site());
 
 		if params.is_empty() {
 			return quote!({
 				#jsonrpsee::core::params::ArrayParams::new()
 			});
 		}
 
+		if params.iter().any(|(param, _)| param.ident == p) {
+			panic!(
+				"Cannot use `{}` as a parameter name because it's overlapping with an internal variable in the generated code. Change it something else to make it work", ILLEGAL_PARAM_NAME
+			);
+		}
+
 		match param_kind {
 			ParamKind::Map => {
 				// Extract parameter names.
@@ -229,27 +242,37 @@ impl RpcDescription {
 					let (value, _value_type) = pair.1;
 					quote!(#name, #value)
 				});
+
+				// It's possible that the user has a parameter named `ILLEGAL_PARAM_NAME` in there API
+				// which would conflict with our internal parameter name
+				//
+				// We will throw an error if that is the case.
+				if param_names.iter().any(|name| name == ILLEGAL_PARAM_NAME) {
+					panic!("Cannot use `{}` as a parameter name", ILLEGAL_PARAM_NAME);
+				}
+
 				quote!({
-					let mut params = #jsonrpsee::core::params::ObjectParams::new();
+					let mut #p = #jsonrpsee::core::params::ObjectParams::new();
 					#(
-						if let Err(err) = params.insert( #params_insert ) {
+						if let Err(err) = #p.insert( #params_insert ) {
 							panic!("Parameter `{}` cannot be serialized: {:?}", stringify!( #params_insert ), err);
 						}
 					)*
-					params
+					#p
 				})
 			}
 			ParamKind::Array => {
 				// Throw away the type.
 				let params = params.iter().map(|(param, _param_type)| param);
+
 				quote!({
-					let mut params = #jsonrpsee::core::params::ArrayParams::new();
+					let mut #p = #jsonrpsee::core::params::ArrayParams::new();
 					#(
-						if let Err(err) = params.insert( #params ) {
+						if let Err(err) = #p.insert( #params ) {
 							panic!("Parameter `{}` cannot be serialized: {:?}", stringify!( #params ), err);
 						}
 					)*
-					params
+					#p
 				})
 			}
 		}

tests/proc-macro-core/src/lib.rs

@@ -31,7 +31,7 @@ pub trait Api {
 	async fn async_call(&self, a: String) -> Result<String, ErrorObjectOwned>;
 
 	#[subscription(name = "subscribe", item = PubSubItem)]
-	async fn sub(&self, kind: PubSubKind, p: PubSubParams) -> SubscriptionResult;
+	async fn sub(&self, kind: PubSubKind, params: PubSubParams) -> SubscriptionResult;
 
 	#[subscription(name = "subscribeSync", item = String)]
 	fn sync_sub(&self, a: String) -> SubscriptionResult;