cargo-careful panics due to stat being left uninitialized

[Deewiant]

https://github.com/RalfJung/cargo-careful triggers a panic attempted to leave type `libc::unix::linux_like::linux::gnu::b64::x86_64::stat` uninitialized, which is invalid from within ipc-channel.

Easily reproduced by sending an IpcReceiver over an IpcOneShotServer. For instance:

use ipc_channel::ipc::{self, IpcOneShotServer, IpcReceiver, IpcSender};
fn main() -> Result<(), Box<dyn ::std::error::Error>> {
    let (server, name) = IpcOneShotServer::new()?;
    let (tx, rx) = ipc::channel::<i32>()?;
    IpcSender::connect(name.clone())?.send(rx)?;
    tx.send(1)?;
    let rx2: IpcReceiver<i32> = server.accept()?.1;
    let x = rx2.recv()?;
    println!("connected via {} and got {}", name, x);
    Ok(())
}

Then:

$ RUST_BACKTRACE=1 cargo +nightly careful run
Preparing a careful sysroot (target: x86_64-unknown-linux-gnu)... done
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/bug`
thread 'main' panicked at 'attempted to leave type `libc::unix::linux_like::linux::gnu::b64::x86_64::stat` uninitialized, which is invalid', /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/platform/unix/mod.rs:1118:22
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: core::mem::uninitialized
             at /.../.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/mem/mod.rs:691:9
   4: ipc_channel::platform::unix::is_socket
             at /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/platform/unix/mod.rs:1118:22
   5: ipc_channel::platform::unix::recv
             at /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/platform/unix/mod.rs:947:16
   6: ipc_channel::platform::unix::OsIpcReceiver::recv
             at /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/platform/unix/mod.rs:145:9
   7: ipc_channel::platform::unix::OsIpcOneShotServer::accept
             at /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/platform/unix/mod.rs:650:59
   8: ipc_channel::ipc::IpcOneShotServer<T>::accept
             at /.../.cargo/registry/src/github.com-1ecc6299db9ec823/ipc-channel-0.16.0/src/ipc.rs:782:13
   9: bug::main
             at ./src/main.rs:7:33
  10: core::ops::function::FnOnce::call_once
             at /.../.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:251:5

Whereas without cargo-careful there is no problem:

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/bug`
connected via /tmp/.tmpaoO7IE/socket and got 1

I suppose this would be fixed by #280 replacing that mem::uninitialized() with MaybeUninit. Still, I figured I'd report this for visibility in case anybody else runs into it.

[mrobinson]

I'm not seeing this one any longer.