error: generic parameters may not be used in const operations
  --> $DIR/trivial-anon-const-use-cases.rs:14:19
   |
LL |     stuff: [u8; { S + 1 }], // `S + 1` is NOT a valid const expression in this context.
   |                   ^ cannot perform const operation using `S`
   |
   = help: const parameters may only be used as standalone arguments here, i.e. `S`
   = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions

error: aborting due to 1 previous error