error[E0005]: refutable pattern in local binding: `Bar` not covered
  --> $DIR/issue-31561.rs:8:9
   |
LL | / enum Thing {
LL | |     Foo(u8),
LL | |     Bar,
LL | |     Baz
LL | | }
   | |_- `Thing` defined here
...
LL |       let Thing::Foo(y) = Thing::Foo(1);
   |           ^^^^^^^^^^^^^ pattern `Bar` not covered

error: aborting due to previous error

For more information about this error, try `rustc --explain E0005`.