add feature gate doc_masked and tests

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 54d41a030fd..9dad92bb18b 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -376,6 +376,8 @@ declare_features! (
 
     // #[doc(cfg(...))]
     (active, doc_cfg, "1.21.0", Some(43781)),
+    // #[doc(masked)]
+    (active, doc_masked, "1.21.0", None),
 
     // allow `#[must_use]` on functions (RFC 1940)
     (active, fn_must_use, "1.21.0", Some(43302)),
@@ -1229,6 +1231,10 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                     gate_feature_post!(&self, doc_cfg, attr.span,
                         "#[doc(cfg(...))] is experimental"
                     );
+                } else if content.iter().any(|c| c.check_name("masked")) {
+                    gate_feature_post!(&self, doc_masked, attr.span,
+                        "#[doc(masked)] is experimental"
+                    );
                 }
             }
         }