fn_to_numeric_cast_any should not warn cast to pointer

[taiki-e]

Summary

Docs says "Checks for casts of a function pointer to any integer type", but it actually warns cast to pointer too.

It may make sense to have a separate lint that warns against casts to arbitrary types, but I believe it is wrong anyway for a lint that is intended to warn against casts to integers to warn against casts to pointers.

Lint Name

fn_to_numeric_cast_any

Reproducer

I tried this code:

#![warn(clippy::fn_to_numeric_cast_any)]

fn fn1() {}
fn main() {
    let _ = fn1 as *const ();
    let _ = fn1 as *mut ();
}

I saw this happen:

warning: casting function pointer `fn1` to `*const ()`
 --> src/main.rs:5:13
  |
5 |     let _ = fn1 as *const ();
  |             ^^^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `fn1() as *const ()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast_any
note: the lint level is defined here
 --> src/main.rs:1:9
  |
1 | #![warn(clippy::fn_to_numeric_cast_any)]
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: casting function pointer `fn1` to `*mut ()`
 --> src/main.rs:6:13
  |
6 |     let _ = fn1 as *mut ();
  |             ^^^^^^^^^^^^^^ help: did you mean to invoke the function?: `fn1() as *mut ()`
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast_any

I expected to see this happen: no warning

playground

Version

rustc -vV
rustc 1.79.0-nightly (9d79cd5f7 2024-04-05)
binary: rustc
commit-hash: 9d79cd5f79e75bd0d2083260271307ce9acd9081
commit-date: 2024-04-05
host: aarch64-apple-darwin
release: 1.79.0-nightly
LLVM version: 18.1.2

Additional Labels

No response