let_underscore_lock does not trigger for `parking_lot` / non-std locks

[DzenanJupic]

Lint name: let_underscore_lock

I tried this code:

playground

fn main() {
    {
        use parking_lot::{Mutex, lock_api::RawMutex}; // 0.11.2
    
        let mutex: Mutex<()> = Mutex::const_new(RawMutex::INIT, ());
        let _ = mutex.lock();
    }
    {
        use std::sync::Mutex;
    
        let mutex: Mutex<()> = Mutex::new(());
        let _ = mutex.lock().unwrap();
    }
}

I expected to see this happen:

Since parking_lot is widely used, and usually always the preferred alternative compared to the std locks, I expected clippy to know about it.

Instead, this happened:

clippy seems to only care about std locks:

Checking playground v0.0.1 (/playground)
error: non-binding let on a synchronization lock
  --> src/main.rs:13:9
   |
13 |         let _ = mutex.lock().unwrap();
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[deny(clippy::let_underscore_lock)]` on by default
   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_lock

error: could not compile `playground` due to previous error

Meta

rustc 1.57.0-nightly (98c861950 2021-09-27)
binary: rustc
commit-hash: 98c8619502093f34ca82f8f26ccf32e753924440
commit-date: 2021-09-27
host: x86_64-pc-windows-msvc
release: 1.57.0-nightly
LLVM version: 13.0.0

[surechen]

I am very happy to follow up on this issue
@rustbot claim