Option<CoroutineKind>

src/closures.rs

@@ -29,7 +29,7 @@ pub(crate) fn rewrite_closure(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    coro_kind: &ast::CoroutineKind,
+    coro_kind: &Option<ast::CoroutineKind>,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -233,7 +233,7 @@ fn rewrite_closure_fn_decl(
     binder: &ast::ClosureBinder,
     constness: ast::Const,
     capture: ast::CaptureBy,
-    coro_kind: &ast::CoroutineKind,
+    coro_kind: &Option<ast::CoroutineKind>,
     movability: ast::Movability,
     fn_decl: &ast::FnDecl,
     body: &ast::Expr,
@@ -263,8 +263,13 @@ fn rewrite_closure_fn_decl(
     } else {
         ""
     };
-    let is_async = if coro_kind.is_async() { "async " } else { "" };
-    let is_gen = if coro_kind.is_gen() { "gen " } else { "" };
+    let (is_async, is_gen) = if let Some(coro_kind) = coro_kind {
+        let is_async = if coro_kind.is_async() { "async " } else { "" };
+        let is_gen = if coro_kind.is_gen() { "gen " } else { "" };
+        (is_async, is_gen)
+    } else {
+        ("", "")
+    };
     let mover = if matches!(capture, ast::CaptureBy::Value { .. }) {
         "move "
     } else {

src/items.rs

@@ -287,7 +287,7 @@ pub(crate) struct FnSig<'a> {
     decl: &'a ast::FnDecl,
     generics: &'a ast::Generics,
     ext: ast::Extern,
-    coro_kind: Cow<'a, ast::CoroutineKind>,
+    coro_kind: Cow<'a, Option<ast::CoroutineKind>>,
     constness: ast::Const,
     defaultness: ast::Defaultness,
     unsafety: ast::Unsafe,
@@ -343,7 +343,8 @@ fn to_str(&self, context: &RewriteContext<'_>) -> String {
         result.push_str(&*format_visibility(context, self.visibility));
         result.push_str(format_defaultness(self.defaultness));
         result.push_str(format_constness(self.constness));
-        result.push_str(format_coro(&self.coro_kind));
+        self.coro_kind
+            .map(|coro_kind| result.push_str(format_coro(&coro_kind)));
         result.push_str(format_unsafety(self.unsafety));
         result.push_str(&format_extern(
             self.ext,

src/utils.rs

@@ -79,7 +79,6 @@ pub(crate) fn format_coro(coro_kind: &ast::CoroutineKind) -> &'static str {
     match coro_kind {
         ast::CoroutineKind::Async { .. } => "async ",
         ast::CoroutineKind::Gen { .. } => "gen ",
-        ast::CoroutineKind::None => "",
     }
 }