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: add `#![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`.