Fix fail, named function cast to raw ptr, == it

[A4-Tacks]

Description

fn main() {
    let _x = main as *const () == main as *const ();
}

Run cargo clippy --fix outputs:

    Checking test_ v0.1.0 (/home/lrne/Project/Rust/test_)
warning: failed to automatically apply fixes suggested by rustc to crate `test_`

after fixes were automatically applied the compiler reported errors within these files:

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
error[E0308]: arguments to this function are incorrect
    --> src/main.rs:2:14
     |
2    |     let _x = std::ptr::eq(main, main);
     |              ^^^^^^^^^^^^
     |
note: expected `*const _`, found fn item
    --> src/main.rs:2:27
     |
2    |     let _x = std::ptr::eq(main, main);
     |                           ^^^^
     = note: expected raw pointer `*const _`
                    found fn item `fn() {main}`
note: expected `*const _`, found fn item
    --> src/main.rs:2:33
     |
2    |     let _x = std::ptr::eq(main, main);
     |                                 ^^^^
     = note: expected raw pointer `*const _`
                    found fn item `fn() {main}`
note: function defined here
    --> /home/lrne/.rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:2143:8
     |
2143 | pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool {
     |        ^^

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.
Original diagnostics will follow.

warning: equal expressions as operands to `==`
 --> src/main.rs:2:14
  |
2 |     let _x = main as *const () == main as *const ();
  |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#eq_op
  = note: `#[warn(clippy::eq_op)]` on by default

warning: use `std::ptr::eq` when comparing raw pointers
 --> src/main.rs:2:14
  |
2 |     let _x = main as *const () == main as *const ();
  |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::ptr::eq(main, main)`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ptr_eq
  = note: `#[warn(clippy::ptr_eq)]` on by default

warning: `test_` (bin "test_" test) generated 2 warnings (run `cargo clippy --fix --bin "test_" --tests` to apply 1 suggestion)
warning: failed to automatically apply fixes suggested by rustc to crate `test_`

after fixes were automatically applied the compiler reported errors within these files:

  * src/main.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
error[E0308]: arguments to this function are incorrect
    --> src/main.rs:2:14
     |
2    |     let _x = std::ptr::eq(main, main);
     |              ^^^^^^^^^^^^
     |
note: expected `*const _`, found fn item
    --> src/main.rs:2:27
     |
2    |     let _x = std::ptr::eq(main, main);
     |                           ^^^^
     = note: expected raw pointer `*const _`
                    found fn item `fn() {main}`
note: expected `*const _`, found fn item
    --> src/main.rs:2:33
     |
2    |     let _x = std::ptr::eq(main, main);
     |                                 ^^^^
     = note: expected raw pointer `*const _`
                    found fn item `fn() {main}`
note: function defined here
    --> /home/lrne/.rustup/toolchains/stable-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:2143:8
     |
2143 | pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool {
     |        ^^

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0308`.
Original diagnostics will follow.

warning: `test_` (bin "test_") generated 2 warnings (2 duplicates)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.81s

Version

rustc 1.82.0 (f6e511eec 2024-10-15)
binary: rustc
commit-hash: f6e511eec7342f59a25f7c0534f1dbea00d01b14
commit-date: 2024-10-15
host: aarch64-unknown-linux-gnu
release: 1.82.0
LLVM version: 19.1.1

Additional Labels

No response

[samueltardieu]

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