error: expected one of `,`, `.`, `?`, `}`, or an operator, found `with`
  --> $DIR/removed-syntax-with-1.rs:8:25
   |
LL |     let b = S { foo: () with a };
   |                         ^^^^ expected one of `,`, `.`, `?`, `}`, or an operator here

error[E0063]: missing field `bar` in initializer of `main::S`
  --> $DIR/removed-syntax-with-1.rs:8:13
   |
LL |     let b = S { foo: () with a };
   |             ^ missing `bar`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0063`.