error[E0608]: cannot index into a value of type `()`
  --> $DIR/coercion-check-for-indexing-expression-issue-40861.rs:4:7
   |
LL |     ()[f(&[1.0])];
   |       ^^^^^^^^^^^
   |
   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0608`.
