Fix panic from repeat clones of TypeErasedBox (#2842)

This PR fixes a panic that would result from cloning a cloneable
`TypeErasedBox` twice.

----

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rust-runtime/aws-smithy-types/src/config_bag.rs

@@ -855,6 +855,13 @@ mod test {
  layer_1.unset::<TestStr>();
  assert!(layer_1.try_clone().unwrap().load::<TestStr>().is_none());
 
+ // It is cloneable multiple times in succession
+ let _ = layer_1
+ .try_clone()
+ .expect("clone 1")
+ .try_clone()
+ .expect("clone 2");
+
  #[derive(Clone, Debug)]
  struct Rope(String);
  impl Storable for Rope {

rust-runtime/aws-smithy-types/src/type_erasure.rs

@@ -122,7 +122,13 @@ impl TypeErasedBox {
 
 impl fmt::Debug for TypeErasedBox {
  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- f.write_str("TypeErasedBox:")?;
+ f.write_str("TypeErasedBox[")?;
+ if self.clone.is_some() {
+ f.write_str("Clone")?;
+ } else {
+ f.write_str("!Clone")?;
+ }
+ f.write_str("]:")?;
  (self.debug)(&self.field, f)
  }
 }
@@ -145,7 +151,7 @@ impl TypeErasedBox {
  fmt::Debug::fmt(value.downcast_ref::<T>().expect("type-checked"), f)
  };
  let clone = |value: &Box<dyn Any + Send + Sync>| {
- TypeErasedBox::new(value.downcast_ref::<T>().expect("typechecked").clone())
+ TypeErasedBox::new_with_clone(value.downcast_ref::<T>().expect("typechecked").clone())
  };
  Self {
  field: Box::new(value),
@@ -292,8 +298,11 @@ mod tests {
  .0 = "3";
 
  let bar_erased = bar.erase();
- assert_eq!("TypeErasedBox:Foo(\"3\")", format!("{foo_erased:?}"));
- assert_eq!("TypeErasedBox:Bar(2)", format!("{bar_erased:?}"));
+ assert_eq!(
+ "TypeErasedBox[!Clone]:Foo(\"3\")",
+ format!("{foo_erased:?}")
+ );
+ assert_eq!("TypeErasedBox[!Clone]:Bar(2)", format!("{bar_erased:?}"));
 
  let bar_erased = TypedBox::<Foo>::assume_from(bar_erased).expect_err("it's not a Foo");
  let mut bar = TypedBox::<Bar>::assume_from(bar_erased).expect("it's a Bar");