feat(rln): update examples to support multi-message-id feature and adjust README instructions

Author: vinhtc27

rln/Cargo.toml

@@ -63,7 +63,7 @@ document-features = { version = "0.2.12", optional = true }
 criterion = { version = "0.8.0", features = ["html_reports"] }
 
 [features]
-default = ["parallel", "pmtree-ft", "multi-message-id"]
+default = ["parallel", "pmtree-ft"]
 stateless = []
 parallel = [
     "rayon",
@@ -90,6 +90,16 @@ required-features = ["pmtree-ft"]
 name = "poseidon_tree_benchmark"
 harness = false
 
+
+[[example]]
+name = "multi_message_id"
+path = "examples/multi_message_id.rs"
+required-features = ["multi-message-id"]
+
+[[example]]
+name = "standard"
+path = "examples/standard.rs"
+
 [package.metadata.docs.rs]
 all-features = true
 

rln/examples/Readme.md

@@ -2,16 +2,23 @@
 
 This example demonstrates how to use RLN .
 
-## Standard rln example
+## Standard example with default features
 
 ```bash
 cd rln/examples
 cargo run --example standard
 ```
 
-## Multi-message-id feature enable example
+## Standard example with multi-message-id feature enabled for backward compatibility
 
 ```bash
 cd rln/examples
-cargo run --example multi_message_id
+cargo run --example standard --features multi-message-id
+```
+
+## Example with multi-message-id feature enabled
+
+```bash
+cd rln/examples
+cargo run --example multi_message_id --features multi-message-id
 ```

rln/examples/multi_message_id.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "multi-message-id")]
+
 use std::{
     fs::File,
     io::Read,

rln/examples/standard.rs

@@ -38,6 +38,19 @@ fn main() {
     let x = hash_to_field_le(signal).unwrap();
 
     // 8. Create witness input for RLN proof generation
+    #[cfg(not(feature = "multi-message-id"))]
+    let witness = RLNWitnessInput::new(
+        identity_secret,
+        user_message_limit,
+        message_id,
+        path_elements,
+        identity_path_index,
+        x,
+        external_nullifier,
+    )
+    .unwrap();
+
+    #[cfg(feature = "multi-message-id")]
     let witness = RLNWitnessInput::new(
         identity_secret,
         user_message_limit,