error[E0109]: const arguments are not allowed on builtin type `usize` --> $DIR/usize-generic-argument-parent.rs:2:18 | LL | let x: usize; | ----- ^^^ const argument not allowed | | | not allowed on builtin type `usize` | help: primitive type `usize` doesn't have generic parameters | LL - let x: usize; LL + let x: usize; | error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0109`.