timsaucer commented on code in PR #21263:
URL: https://github.com/apache/datafusion/pull/21263#discussion_r3029662596
##########
docs/source/library-user-guide/upgrading/54.0.0.md:
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@@ -180,29 +180,50 @@ function. The below diffs are examples from the
associated PRs.
}
```
-If you have a function that is downcasting a UDF, you can replace
-the call to `.as_any()` with `.as_ref() as &dyn Any`. For example
+**Execution Plans:**
+
+```diff
+ impl ExecutionPlan for MyExec {
+- fn as_any(&self) -> &dyn Any {
+- self
+- }
+-
+ fn name(&self) -> &'static str {
+ "MyExec"
+ }
+
+ ...
+ }
+```
+
+If you have code that is downcasting, you can use the new `downcast_ref`
+and `is` methods defined directly on each trait object:
**Before:**
```rust,ignore
-let is_async = func
- .inner()
- .as_any()
- .downcast_ref::<AsyncScalarUDF>()
- .is_some();
+let exec = plan.as_any().downcast_ref::<MyExec>().unwrap();
+let udf = scalar_udf.as_any().downcast_ref::<MyUdf>().unwrap();
```
**After:**
```rust,ignore
-let is_async = (func
- .inner()
- .as_ref() as &dyn Any)
- .downcast_ref::<AsyncScalarUDF>()
- .is_some();
+let exec = plan.downcast_ref::<MyExec>().unwrap();
+let udf = scalar_udf.downcast_ref::<MyUdf>().unwrap();
```
+These methods are available on `dyn ExecutionPlan`, `dyn ScalarUDFImpl`,
+`dyn AggregateUDFImpl`, and `dyn WindowUDFImpl`. They work correctly
+whether the value is a bare reference or behind an `Arc` (Rust
+auto-derefs through the `Arc`).
+
+> **Warning:** Do not cast an `Arc<dyn Trait>` directly to `&dyn Any`.
Review Comment:
Yes, so it renders like this:
<img width="759" height="252" alt="Screenshot 2026-04-02 at 2 31 26 PM"
src="https://github.com/user-attachments/assets/79ff1341-e695-4fc1-8764-223b1adb2b6c";
/>
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