error: use of deprecated function `f1`: removal scheduled for version >= 1.0
  --> tests/ui/warn.rs:15:5
   |
15 |     f1();
   |     ^^
   |
note: the lint level is defined here
  --> tests/ui/warn.rs:1:9
   |
1  | #![deny(warnings)]
   |         ^^^^^^^^
   = note: `#[deny(deprecated)]` implied by `#[deny(warnings)]`

error: use of deprecated function `f2`: Remove me (removal scheduled for version >= 1.0)
  --> tests/ui/warn.rs:16:5
   |
16 |     f2();
   |     ^^

error: use of deprecated function `f3`: Remove me (removal scheduled for version >= 1.0)
  --> tests/ui/warn.rs:17:5
   |
17 |     f3();
   |     ^^