Rename local to ?Send

src/args.rs

@@ -1,18 +1,36 @@
-use syn::parse::{Parse, ParseStream, Result};
+use proc_macro2::Span;
+use syn::parse::{Error, Parse, ParseStream, Result};
+use syn::Token;
 
+#[derive(Copy, Clone)]
 pub struct Args {
-    pub local: bool
+    pub local: bool,
 }
 
 mod kw {
-    syn::custom_keyword!(local);
+    syn::custom_keyword!(Send);
 }
 
 impl Parse for Args {
     fn parse(input: ParseStream) -> Result<Self> {
-        let local: Option<kw::local> = input.parse()?;
-        Ok(Args {
-            local: local.is_some(),
-        })
+        match try_parse(input) {
+            Ok(args) if input.is_empty() => Ok(args),
+            _ => Err(error()),
+        }
     }
 }
+
+fn try_parse(input: ParseStream) -> Result<Args> {
+    if input.peek(Token![?]) {
+        input.parse::<Token![?]>()?;
+        input.parse::<kw::Send>()?;
+        Ok(Args { local: true })
+    } else {
+        Ok(Args { local: false })
+    }
+}
+
+fn error() -> Error {
+    let msg = "expected #[async_trait] or #[async_trait(?Send)]";
+    Error::new(Span::call_site(), msg)
+}

tests/test.rs

@@ -117,12 +117,12 @@ pub async fn test_object_safe_with_default() {
 }
 
 pub async fn test_object_no_send() {
-    #[async_trait(local)]
+    #[async_trait(?Send)]
     trait ObjectSafe: Sync {
         async fn f(&self) {}
     }
 
-    #[async_trait(local)]
+    #[async_trait(?Send)]
     impl ObjectSafe for Struct {
         async fn f(&self) {}
     }