error[E0493]: destructor of `(Foo, Foo)` cannot be evaluated at compile-time
  --> $DIR/E0493.rs:17:17
   |
LL | const F : Foo = (Foo { a : 0 }, Foo { a : 1 }).1;
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - value is dropped here
   |                 |
   |                 the destructor for this type cannot be evaluated in constants

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0493`.