Auto merge of #57321 - petrochenkov:atokens, r=nikomatsakis

Implement basic input validation for built-in attributes

Correct top-level shape (`#[attr]` vs `#[attr(...)]` vs `#[attr = ...]`) is enforced for built-in attributes, built-in attributes must also fit into the "meta-item" syntax (aka the "classic attribute syntax").

For some subset of attributes (found by crater run), errors are lowered to deprecation warnings.

NOTE: This PR previously included https://github.com/rust-lang/rust/pull/57367 as well.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/libsyntax/ext/derive.rs b/src/libsyntax/ext/derive.rs
index d5a51bc1703..7ef09ce5fbd 100644
--- a/src/libsyntax/ext/derive.rs
+++ b/src/libsyntax/ext/derive.rs
@@ -15,6 +15,11 @@ pub fn collect_derives(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) -> Vec
         if attr.path != "derive" {
             return true;
         }
+        if !attr.is_meta_item_list() {
+            cx.span_err(attr.span,
+                        "attribute must be of the form `#[derive(Trait1, Trait2, ...)]`");
+            return false;
+        }
 
         match attr.parse_list(cx.parse_sess,
                               |parser| parser.parse_path_allowing_meta(PathStyle::Mod)) {