Update CHANGELOG

Author: CodaFi

CHANGELOG.md

@@ -5,6 +5,8 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
 
 ## Swift 5.7
 
+  ```
+
 * [SE-0309][]:
 
   Protocols with associated types and `Self` requirements can now be used as the
@@ -72,11 +74,26 @@ _**Note:** This is in reverse chronological order, so newer entries are added to
 
 * [SE-0353][]:
 
-  Further generalizing the above, protocol-constrained types can also be used with `any`:
+  Protocols with primary associated types can now be used in existential types,
+  enabling same-type constraints on those associated types.
 
-  ```swift
-    func findBestGraph(_: [any Graph<Int>]) -> any Graph<Int> {...}
   ```
+  let strings: any Collection<String> = [ "Hello" ]
+  ```
+
+  Note that language features requiring runtime support like dynamic casts
+  (`is`, `as?`, `as!`), as well as generic usages of parameterized existentials
+  in generic types (e.g. `Array<any Collection<Int>>`) involve additional
+  availability checks to use. Back-deploying usages in generic position can be
+  worked around with a generic type-erasing wrapper struct, which is now much
+  simpler to implement:
+
+  ```swift
+  struct AnyCollection<T> {
+    var wrapped: any Collection<T>
+  }
+
+  let arrayOfCollections: [AnyCollection<T>] = [ /**/ ]
 
 * [SE-0358][]: