error[E0658]: :vis fragment specifier is experimental and subject to change (see issue #41022)
  --> $DIR/feature-gate-macro-vis-matcher.rs:14:19
   |
14 | macro_rules! m { ($v:vis) => {} }
   |                   ^^^^^^
   |
   = help: add #![feature(macro_vis_matcher)] to the crate attributes to enable

error: aborting due to previous error

If you want more information on this error, try using "rustc --explain E0658"