use downcast-rs instead of our own AsAny

Cargo.lock

@@ -869,6 +869,8 @@ dependencies = [
 [[package]]
 name = "derive_builder"
 version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddd8db2d51ce241afb74f9e5cf9482de69c4b77657c2ddaf78993eda8ce2ce8c"
 dependencies = [
  "derive_builder_macro",
 ]
@@ -876,6 +878,8 @@ dependencies = [
 [[package]]
 name = "derive_builder_core"
 version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fcf03b84d76c5bb011d983c17e2675ab49f5498f121bf1ceae5b5855b4a4dddd"
 dependencies = [
  "darling",
  "proc-macro2",
@@ -886,6 +890,8 @@ dependencies = [
 [[package]]
 name = "derive_builder_macro"
 version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cae44c47bca4fd1eaeda52b3d0eecb664ddcbc0d4e7b238bae7ec2c931646c0"
 dependencies = [
  "derive_builder_core",
  "syn",
@@ -974,6 +980,12 @@ dependencies = [
  "winapi 0.3.9",
 ]
 
+[[package]]
+name = "downcast-rs"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ea835d29036a4087793836fa931b08837ad5e957da9e23886b29586fb9b6650"
+
 [[package]]
 name = "easy-parallel"
 version = "3.2.0"
@@ -3218,6 +3230,7 @@ dependencies = [
  "async-trait",
  "bounded-vec-deque",
  "derive_builder",
+ "downcast-rs",
  "educe",
  "futures",
  "futures-await-test",

crates/tor-circmgr/Cargo.toml

@@ -34,6 +34,7 @@ tor-rtcompat = { path="../tor-rtcompat", version = "0.1.0"}
 async-trait = "0.1.2"
 bounded-vec-deque = "0.1"
 derive_builder = "0.11"
+downcast-rs = "1.2.0"
 educe = "0.4.6"
 futures = "0.3.14"
 humantime-serde = "1.1.1"

crates/tor-circmgr/src/usage.rs

@@ -1,5 +1,6 @@
 //! Code related to tracking what activities a circuit can be used for.
 
+use downcast_rs::{impl_downcast, Downcast};
 use rand::Rng;
 use serde::{Deserialize, Serialize};
 use std::fmt::{self, Display};
@@ -100,27 +101,14 @@ impl Display for TargetPorts {
     }
 }
 
-use std::any::Any;
-
 /// TODO
-pub trait AsAny {
+pub trait Isolation: Downcast + std::fmt::Debug + Send + Sync + 'static {
-    /// TODO
-    fn as_any(&self) -> &dyn Any;
-}
-
-impl<T: 'static> AsAny for T {
-    fn as_any(&self) -> &dyn Any {
-        self
-    }
-}
-
-/// TODO
-pub trait Isolation: AsAny + std::fmt::Debug + Send + Sync + 'static {
     /// TODO
     fn isolated(&self, other: &dyn Isolation) -> bool;
     /// TODO
     fn join(&self, other: &dyn Isolation) -> JoinResult;
 }
+impl_downcast!(Isolation);
 
 impl<T: IsolationHelper + std::fmt::Debug + Send + Sync + 'static> Isolation for T {
     fn isolated(&self, other: &dyn Isolation) -> bool {