feat: Add anyhow::Error example

Author: TmLev

Cargo.toml

@@ -10,6 +10,7 @@ members = [
     "./examples/tauri/src-tauri",
     "./examples/legacy",
     "./examples/binario",
+    "./examples/anyhow-error",
 ]
 
 [workspace.dependencies]

examples/anyhow-error/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "anyhow-error"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rspc = { path = "../../rspc", features = ["typescript"] }
+specta.workspace = true
+anyhow = "1.0.95"
+thiserror = "2.0.11"
+
+[lints]
+workspace = true

examples/anyhow-error/bindings.ts

@@ -0,0 +1,5 @@
+// This file was generated by [rspc](https://github.com/specta-rs/rspc). Do not edit this file manually.
+
+export type Procedures = {
+	anyhow: { kind: "query", input: any, output: any, error: any },
+}

examples/anyhow-error/src/main.rs

@@ -0,0 +1,40 @@
+use rspc::{Procedure, Router};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+fn main() {
+    let (_procedures, _types) = Router::new()
+        .procedure(
+            //
+            "anyhow",
+            Procedure::builder().query(anyhow_procedure),
+        )
+        .build()
+        .expect("router should be built");
+}
+
+// Some procedure that needs `anyhow::Error` to be compatible with `rspc`.
+async fn anyhow_procedure(_ctx: (), _input: ()) -> Result<String, AnyhowError> {
+    let response = fallible()?; // `?` converts `anyhow::Error` into `AnyhowError`.
+    Ok(response)
+}
+
+fn fallible() -> Result<String, anyhow::Error> {
+    anyhow::bail!("oh no!")
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// Make `anyhow::Error` work where `std::error::Error + Send + 'static` is expected.
+// NB: Define this only once; afterwards, you can import and use it anywhere.
+// See: https://github.com/dtolnay/anyhow/issues/153#issuecomment-833718851
+#[derive(Debug, thiserror::Error)]
+#[error(transparent)]
+struct AnyhowError(#[from] anyhow::Error);
+
+impl rspc::Error for AnyhowError {
+    fn into_procedure_error(self) -> rspc::ProcedureError {
+        let message = format!("something bad happened: {}", self);
+        rspc::ResolverError::new(message, Some(self)).into()
+    }
+}