.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+  schedule: [cron: "0 0 * * *"]
+
+permissions:
+  contents: read
+
+env:
+  RUSTFLAGS: -Dwarnings
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo test --verbose
+
+  fmt:
+    name: Fmt
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: rustfmt
+      - run: cargo fmt -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@nightly
+        with:
+          components: clippy
+      - run: cargo clippy -- -Dwarnings
+
+  outdated:
+    name: Outdated
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/install@cargo-outdated
+      - run: cargo outdated --exit-code 1

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "async-recursion"
-version = "1.0.2"
+version = "1.0.3"
 authors = ["Robert Usher <266585+dcchut@users.noreply.github.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -15,7 +15,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = { version = "1.0", default-features = false }
 quote = { version = "1.0", default-features = false }
-syn = { version = "1.0", features = ["full", "parsing", "printing", "proc-macro", "clone-impls"],  default-features = false }
+syn = { version = "2.0", features = ["full", "parsing", "printing", "proc-macro", "clone-impls"],  default-features = false }
 
 [dev-dependencies]
 futures-executor = "0.3"

README.md

@@ -2,7 +2,7 @@
 
 [![Latest version](https://img.shields.io/crates/v/async-recursion)](https://crates.io/crates/async-recursion)
 [![crates.io downloads](https://img.shields.io/crates/d/async_recursion)](https://crates.io/crates/async-recursion)
-[![Build Status](https://img.shields.io/github/actions/workflow/status/dcchut/async-recursion/rust.yml?branch=master)](https://github.com/dcchut/async-recursion/actions)
+[![Build Status](https://img.shields.io/github/actions/workflow/status/dcchut/async-recursion/ci.yml?branch=master)](https://github.com/dcchut/async-recursion/actions)
 ![Apache/MIT2.0 License](https://img.shields.io/crates/l/async-recursion)
 
 Procedural macro for recursive async functions.
@@ -13,12 +13,10 @@ Procedural macro for recursive async functions.
 ## Motivation
 Consider the following recursive implementation of the fibonacci numbers:
 
-```rust,ignore
-async fn fib(n : u32) -> u64 {
+```rust,compile_fail
+async fn fib(n : u32) -> u32 {
    match n {
-       0     => panic!("zero is not a valid argument to fib()!"),
-       1 | 2 => 1,
-       3     => 2,
+       0 | 1 => 1,
        _ => fib(n-1).await + fib(n-2).await
    }
 }
@@ -28,13 +26,13 @@ The compiler helpfully tells us that:
 
 ```console
 error[E0733]: recursion in an `async fn` requires boxing
---> src/main.rs:1:26
+ --> src/main.rs:1:26
   |
-1 | async fn fib(n : u32) -> u64 {
+1 | async fn fib(n : u32) -> u32 {
   |                          ^^^ recursive `async fn`
   |
- = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`.
- = note: consider using the `async_recursion` crate: https://crates.io/crates/async_recursion
+  = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`
+  = note: consider using the `async_recursion` crate: https://crates.io/crates/async_recursion
 ```
 
 This crate provides an attribute macro to automatically convert an async function 
@@ -46,12 +44,10 @@ to one returning a boxed `Future`.
 use async_recursion::async_recursion;
 
 #[async_recursion]
-async fn fib(n : u32) -> u64 {
+async fn fib(n : u32) -> u32 {
    match n {
-       0     => panic!("zero is not a valid argument to fib()!"),
-       1 | 2 => 1,
-       3     => 2,
-       _ => fib(n-1).await + fib(n-2).await
+      0 | 1 => 1,
+      _ => fib(n-1).await + fib(n-2).await
    }
 }
 ```

rustfmt.toml

@@ -0,0 +1,2 @@
+group_imports = "StdExternalCrate"
+imports_granularity = "Crate"

src/expand.rs

@@ -1,8 +1,11 @@
-use crate::parse::{AsyncItem, RecursionArgs};
 use proc_macro2::{Span, TokenStream};
 use quote::{quote, ToTokens};
-use syn::punctuated::Punctuated;
-use syn::{parse_quote, Block, FnArg, Lifetime, ReturnType, Signature, Type, WhereClause};
+use syn::{
+    parse_quote, punctuated::Punctuated, Block, FnArg, Lifetime, ReturnType, Signature, Type,
+    WhereClause,
+};
+
+use crate::parse::{AsyncItem, RecursionArgs};
 
 impl ToTokens for AsyncItem {
     fn to_tokens(&self, tokens: &mut TokenStream) {
@@ -75,7 +78,7 @@ fn transform_sig(sig: &mut Signature, args: &RecursionArgs) {
         for ra in &mut ref_arguments {
             // If this reference arg doesn't have a lifetime, give it an explicit one
             if ra.lifetime.is_none() {
-                let lt = Lifetime::new(&format!("'life{}", counter), Span::call_site());
+                let lt = Lifetime::new(&format!("'life{counter}"), Span::call_site());
 
                 lifetimes.push(ArgLifetime::New(parse_quote!(#lt)));
 

src/parse.rs

@@ -1,6 +1,9 @@
 use proc_macro2::Span;
-use syn::parse::{Error, Parse, ParseStream, Result};
-use syn::{token::Question, ItemFn, Token};
+use syn::{
+    parse::{Error, Parse, ParseStream, Result},
+    token::Question,
+    ItemFn, Token,
+};
 
 pub struct AsyncItem(pub ItemFn);
 

tests/ui/must_use.stderr

@@ -2,7 +2,7 @@ error: unused return value of `apples` that must be used
  --> tests/ui/must_use.rs:9:5
   |
 9 |     apples(3);
-  |     ^^^^^^^^^^
+  |     ^^^^^^^^^
   |
 note: the lint level is defined here
  --> tests/ui/must_use.rs:1:9