error[E0004]: non-exhaustive patterns: type `&A` is non-empty
  --> $DIR/issue-78123-non-exhaustive-reference.rs:5:11
   |
LL | enum A {}
   | --------- `A` defined here
...
LL |     match a {}
   |           ^
   |
   = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
   = note: the matched value is of type `&A`
   = note: references are always considered inhabited

error: aborting due to previous error

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