error[E0493]: destructor of `helper::Foo` cannot be evaluated at compile-time
  --> $DIR/const-promoted-opaque.rs:28:26
   |
LL |     let _: &'static _ = &FOO;
   |                          ^^^ the destructor for this type cannot be evaluated in constants
LL |
LL | };
   | - value is dropped here

error[E0716]: temporary value dropped while borrowed
  --> $DIR/const-promoted-opaque.rs:36:26
   |
LL |     let _: &'static _ = &FOO;
   |            ----------    ^^^ creates a temporary value which is freed while still in use
   |            |
   |            type annotation requires that borrow lasts for `'static`
LL |
LL | }
   | - temporary value is freed at the end of this statement

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0493, E0716.
For more information about an error, try `rustc --explain E0493`.