Only suggest changing #[derive(mymacro)] to #[mymacro] for attribute macros

Author: joshtriplett

compiler/rustc_resolve/src/macros.rs

@@ -659,6 +659,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             if !path.span.from_expansion()
                 && kind == MacroKind::Derive
                 && !ext.macro_kinds().contains(MacroKinds::DERIVE)
+                && ext.macro_kinds().contains(MacroKinds::ATTR)
             {
                 err.remove_surrounding_derive = Some(RemoveSurroundingDerive { span: path.span });
                 err.add_as_non_derive = Some(AddAsNonDerive { macro_path: &path_str });

tests/ui/proc-macro/macro-namespace-reserved-2.stderr

@@ -95,14 +95,6 @@ error: expected derive macro, found macro `crate::my_macro`
    |
 LL | #[derive(crate::my_macro)]
    |          ^^^^^^^^^^^^^^^ not a derive macro
-   |
-help: remove from the surrounding `derive()`
-  --> $DIR/macro-namespace-reserved-2.rs:50:10
-   |
-LL | #[derive(crate::my_macro)]
-   |          ^^^^^^^^^^^^^^^
-   = help: add as non-Derive macro
-           `#[crate::my_macro]`
 
 error: cannot find macro `my_macro_attr` in this scope
   --> $DIR/macro-namespace-reserved-2.rs:28:5