error[E0005]: refutable pattern in local binding: `Bar` and `Baz` not covered
  --> $DIR/issue-31561.rs:8:9
   |
LL | / enum Thing {
LL | |     Foo(u8),
LL | |     Bar,
   | |     --- not covered
LL | |     Baz
   | |     --- not covered
LL | | }
   | |_- `Thing` defined here
...
LL |       let Thing::Foo(y) = Thing::Foo(1);
   |           ^^^^^^^^^^^^^ patterns `Bar` and `Baz` not covered
   |
   = note: `let` bindings require an "irrefutable pattern", like a `struct` or an `enum` with only one variant
   = note: for more information, visit https://doc.rust-lang.org/book/ch18-02-refutability.html
help: you might want to use `if let` to ignore the variant that isn't matched
   |
LL |     if let Thing::Foo(y) = Thing::Foo(1) { /* */ }
   |

error: aborting due to previous error

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