error[E0618]: expected function, found `{float}`
  --> $DIR/issue-45965.rs:2:30
   |
LL |     let a = |r: f64| if r != 0.0(r != 0.0) { 1.0 } else { 0.0 };
   |                              ^^^----------
   |                              |
   |                              call expression requires function

error: aborting due to previous error

For more information about this error, try `rustc --explain E0618`.