Rollup merge of rust-lang#128925 - dingxiangfei2009:smart-ptr-helper-attr, r=compiler-errors

derive(SmartPointer): register helper attributes Fix rust-lang#128888 This PR enables built-in macros to register helper attributes, if any, to support correct name resolution in the correct lexical scope under the macros. Also, `#[pointee]` is moved into the scope under `derive(SmartPointer)`. cc `@Darksonn` `@davidtwco`

Author: matthiaskrgr

core/src/marker.rs

@@ -1060,7 +1060,7 @@ pub trait FnPtr: Copy + Clone {
 }
 
 /// Derive macro generating impls of traits related to smart pointers.
-#[rustc_builtin_macro]
+#[rustc_builtin_macro(SmartPointer, attributes(pointee))]
 #[allow_internal_unstable(dispatch_from_dyn, coerce_unsized, unsize)]
 #[unstable(feature = "derive_smart_pointer", issue = "123430")]
 pub macro SmartPointer($item:item) {