error[E0435]: attempt to use a non-constant value in a constant
  --> $DIR/legacy-const-generics-bad.rs:7:35
   |
LL |     let a = 1;
   |     ----- help: consider using `const` instead of `let`: `const a`
LL |     legacy_const_generics::foo(0, a, 2);
   |                                   ^ non-constant value

error: generic parameters may not be used in const operations
  --> $DIR/legacy-const-generics-bad.rs:12:35
   |
LL |     legacy_const_generics::foo(0, N + 1, 2);
   |                                   ^ cannot perform const operation using `N`
   |
   = help: const parameters may only be used as standalone arguments, i.e. `N`
   = help: use `#![feature(generic_const_exprs)]` to allow generic const expressions

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0435`.