Updates release notes for PR #4124

.release-notes/next-release.md

@@ -0,0 +1,25 @@
+## Allow constructor expressions to be auto-recovered in assignments or arguments
+
+Previously for the following code:
+
+```pony
+actor Main
+  new create(env: Env) =>
+    Bar.take_foo(Foo(88))
+    let bar: Foo iso = Foo(88)
+
+class Foo
+  new create(v: U8) =>
+    None
+
+primitive Bar
+  fun take_foo(foo: Foo iso) =>
+    None
+```
+
+You'd get compilation errors "argument not assignable to parameter" and "right side must be a subtype of left side" for the two lines in `Main.create()`.
+
+We've added checks to see if the constructor expressions can be implicitly auto-recovered, and if they can, no compilation error is generated.
+
+This only applies to cases where the type of the parameter (or the `let` binding) is a simple type, i.e. not a union, intersection or tuple type.
+