1 error[E0618]: expected function, found `usize`
2 --> $DIR/const-as-fn.rs:4:5
4 LL | const FOO: usize = 0;
5 | --------------------- `FOO` defined here
10 | call expression requires function
12 error: aborting due to previous error
14 For more information about this error, try `rustc --explain E0618`.