error: generic parameters may not be used in const operations
  --> $DIR/issue-80375.rs:1:41
   |
LL | struct MyArray<const COUNT: usize>([u8; COUNT + 1]);
   |                                         ^^^^^ cannot perform const operation using `COUNT`
   |
   = help: const parameters may only be used as standalone arguments, i.e. `COUNT`
   = help: use `#![feature(generic_const_exprs)]` to allow generic const expressions

error: aborting due to previous error

