error[E0435]: attempt to use a non-constant value in a constant --> $DIR/issue-3521.rs:8:15 | LL | let foo: isize = 100; | ------- help: consider using `const` instead of `let`: `const foo` ... LL | Bar = foo | ^^^ non-constant value error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0435`.