`uninit_vec` FP on `Vec<MaybeUninit<T>>`

[digama0]

Summary

Basic examples of uninit_vec seem to be broken. I think this is a regression but I'm not positive. In particular the example from #10407 is also broken. In short, the lint is supposed to not fire if the element type is MaybeUninit<T> or similar types based on it which allow uninit values, but it doesn't seem to work.

Lint Name

uninit_vec

Reproducer

I tried this code:

#![warn(clippy::uninit_vec)]

use std::mem::MaybeUninit;

pub fn new_uninit<T>(size: usize) -> Box<[MaybeUninit<T>]> {
    let mut res = Vec::<MaybeUninit<T>>::with_capacity(size);
    unsafe { res.set_len(size) };
    res.into_boxed_slice()
}

I saw this happen:

warning: calling `set_len()` immediately after reserving a buffer creates uninitialized values
 --> src/main.rs:6:5
  |
6 |     let mut res = Vec::<MaybeUninit<T>>::with_capacity(size);
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
7 |     unsafe { res.set_len(size) };
  |              ^^^^^^^^^^^^^^^^^
  |
  = help: initialize the buffer or wrap the content in `MaybeUninit`
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninit_vec

I expected to see this happen: no error

Version

rustc 1.70.0-nightly (478cbb42b 2023-03-28)
binary: rustc
commit-hash: 478cbb42b730ba4739351b72ce2aa928e78e2f81
commit-date: 2023-03-28
host: x86_64-unknown-linux-gnu
release: 1.70.0-nightly
LLVM version: 16.0.0

Additional Labels

No response