error[E0004]: non-exhaustive patterns: type `&A` is non-empty
  --> $DIR/issue-78123-non-exhaustive-reference.rs:6:11
   |
LL |     match a {}
   |           ^
   |
note: `A` defined here
  --> $DIR/issue-78123-non-exhaustive-reference.rs:1:6
   |
LL | enum A {}
   |      ^
   = note: the matched value is of type `&A`
   = note: references are always considered inhabited
help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern as shown
   |
LL ~     match a {
LL +         _ => todo!(),
LL +     }
   |

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0004`.