Auto merge of #116408 - matthiaskrgr:rollup-hmolg4m, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #115961 (Replace 'mutex' with 'lock' in RwLock documentation)
 - #116146 (Clarify `arg` and `args` documentation)
 - #116363 (Adapt `todo!` documentation to mention displaying custom values)
 - #116365 (bootstrap: make copying linker binaries conditional)
 - #116388 (rustdoc: fix & clean up handling of cross-crate higher-ranked parameters)
 - #116393 (Emit feature gate *warning* for `auto` traits pre-expansion)
 - #116395 (Mark myself as vacation or whatever)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 6 insertions, 1 deletions

diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index aad4edaba90..cc54cc5bebb 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -813,7 +813,12 @@ impl<'a> Parser<'a> {
     fn parse_item_trait(&mut self, attrs: &mut AttrVec, lo: Span) -> PResult<'a, ItemInfo> {
         let unsafety = self.parse_unsafety(Case::Sensitive);
         // Parse optional `auto` prefix.
-        let is_auto = if self.eat_keyword(kw::Auto) { IsAuto::Yes } else { IsAuto::No };
+        let is_auto = if self.eat_keyword(kw::Auto) {
+            self.sess.gated_spans.gate(sym::auto_traits, self.prev_token.span);
+            IsAuto::Yes
+        } else {
+            IsAuto::No
+        };
 
         self.expect_keyword(kw::Trait)?;
         let ident = self.parse_ident()?;