Split async-std support and refactor

Cargo.toml

@@ -12,7 +12,8 @@ arbitrary = [ ]
 
 std = [ ]
 
-async-std = [ "dep:async-std", "async-std/alloc", "async-std/default" ]
+async-std = [ "dep:async-std" ]
+async-std-task = [ "async-std", "async-std/alloc", "async-std/default" ]
 tokio1 = [ "dep:tokio1" ]
 tokio1-sync = [ "tokio1", "tokio1/sync" ]
 tokio1-task = [ "tokio1", "tokio1/rt" ]

src/impl_async_std.rs

@@ -1,3 +1,5 @@
+#[cfg(feature = "async-std-task")]
+mod impl_task {
     use async_std::task::JoinHandle;
 
     use crate::{DropGuard, DropGuarded};
@@ -20,3 +22,4 @@ impl<T> core::future::Future for DropGuard<JoinHandle<T>> {
             core::pin::Pin::new(handle).poll(cx)
         }
     }
+}

src/impl_tokio1.rs

@@ -1,5 +1,3 @@
-use crate::DropGuarded;
-
 #[cfg(feature = "tokio1-task")]
 mod impl_task {
     use crate::{DropGuard, DropGuarded};
@@ -28,17 +26,20 @@ mod impl_task {
 }
 
 #[cfg(feature = "tokio1-sync")]
+mod impl_sync {
+    use crate::DropGuarded;
+
     impl DropGuarded for tokio1::sync::oneshot::Sender<()> {
         #[inline]
         fn cancel(self) {
             let _ = self.send(());
         }
     }
-
-#[cfg(all(feature = "tokio1-sync", feature = "std"))]
+    #[cfg(feature = "std")]
     impl DropGuarded for std::sync::Arc<tokio1::sync::Semaphore> {
         #[inline]
         fn cancel(self) {
             self.close();
         }
     }
+}