syntax: Do not accidentally treat multi-segment meta-items as single-segment

2 files changed, 8 insertions, 9 deletions

diff --git a/src/libsyntax_ext/deriving/custom.rs b/src/libsyntax_ext/deriving/custom.rs
index cfc3c931598..e73110717e9 100644
--- a/src/libsyntax_ext/deriving/custom.rs
+++ b/src/libsyntax_ext/deriving/custom.rs
@@ -17,9 +17,11 @@ struct MarkAttrs<'a>(&'a [ast::Name]);
 
 impl<'a> Visitor<'a> for MarkAttrs<'a> {
     fn visit_attribute(&mut self, attr: &Attribute) {
-        if self.0.contains(&attr.name()) {
-            mark_used(attr);
-            mark_known(attr);
+        if let Some(ident) = attr.ident() {
+            if self.0.contains(&ident.name) {
+                mark_used(attr);
+                mark_known(attr);
+            }
         }
     }
 
diff --git a/src/libsyntax_ext/deriving/generic/mod.rs b/src/libsyntax_ext/deriving/generic/mod.rs
index b8f96c5bc0e..2bb98c1bf62 100644
--- a/src/libsyntax_ext/deriving/generic/mod.rs
+++ b/src/libsyntax_ext/deriving/generic/mod.rs
@@ -463,12 +463,9 @@ impl<'a> TraitDef<'a> {
                 let mut attrs = newitem.attrs.clone();
                 attrs.extend(item.attrs
                     .iter()
-                    .filter(|a| {
-                        match &*a.name().as_str() {
-                            "allow" | "warn" | "deny" | "forbid" | "stable" | "unstable" => true,
-                            _ => false,
-                        }
-                    })
+                    .filter(|a| a.ident_str().map_or(false, |name| {
+                        ["allow", "warn", "deny", "forbid", "stable", "unstable"].contains(&name)
+                    }))
                     .cloned());
                 push(Annotatable::Item(P(ast::Item { attrs: attrs, ..(*newitem).clone() })))
             }