warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:16:20
   |
LL |     let _zst_ref = &foo;
   |                    ^^^^
   |
   = note: `#[warn(function_references)]` on by default

warning: cast `fn_item` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:19:25
   |
LL |     let _indirect_ref = &fn_item;
   |                         ^^^^^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:21:25
   |
LL |     let _cast_zst_ptr = &foo as *const _;
   |                         ^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:23:38
   |
LL |     let _coerced_zst_ptr: *const _ = &foo;
   |                                      ^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:26:20
   |
LL |     let _zst_ref = &mut foo;
   |                    ^^^^^^^^

warning: cast `mut_fn_item` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:29:25
   |
LL |     let _indirect_ref = &mut mut_fn_item;
   |                         ^^^^^^^^^^^^^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:31:25
   |
LL |     let _cast_zst_ptr = &mut foo as *mut _;
   |                         ^^^^^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:33:36
   |
LL |     let _coerced_zst_ptr: *mut _ = &mut foo;
   |                                    ^^^^^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:43:22
   |
LL |     println!("{:p}", &foo);
   |                      ^^^^

warning: cast `bar` with `as fn(_) -> _` to use it as a pointer
  --> $DIR/function-references.rs:45:22
   |
LL |     println!("{:p}", &bar);
   |                      ^^^^

warning: cast `baz` with `as fn(_, _) -> _` to use it as a pointer
  --> $DIR/function-references.rs:47:22
   |
LL |     println!("{:p}", &baz);
   |                      ^^^^

warning: cast `unsafe_fn` with `as unsafe fn()` to use it as a pointer
  --> $DIR/function-references.rs:49:22
   |
LL |     println!("{:p}", &unsafe_fn);
   |                      ^^^^^^^^^^

warning: cast `c_fn` with `as extern "C" fn()` to use it as a pointer
  --> $DIR/function-references.rs:51:22
   |
LL |     println!("{:p}", &c_fn);
   |                      ^^^^^

warning: cast `unsafe_c_fn` with `as unsafe extern "C" fn()` to use it as a pointer
  --> $DIR/function-references.rs:53:22
   |
LL |     println!("{:p}", &unsafe_c_fn);
   |                      ^^^^^^^^^^^^

warning: cast `variadic_fn` with `as unsafe extern "C" fn(_, ...)` to use it as a pointer
  --> $DIR/function-references.rs:55:22
   |
LL |     println!("{:p}", &variadic_fn);
   |                      ^^^^^^^^^^^^

warning: cast `std::env::var` with `as fn(_) -> _` to use it as a pointer
  --> $DIR/function-references.rs:57:22
   |
LL |     println!("{:p}", &std::env::var::<String>);
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^

warning: cast `foo` with `as fn() -> _` to use it as a pointer
  --> $DIR/function-references.rs:63:41
   |
LL |         std::mem::transmute::<_, usize>(&foo);
   |                                         ^^^^

warning: 17 warnings emitted