Tracking Issue for StdioExt

Feature gate: #![feature(stdio_swap)]

This is a tracking issue for the std::os::{unix, windows}::io::StdioExt extension traits
that provide ways to redirect stdio to new file handles.

Public API

// unix
pub trait StdioExt {
    fn set_fd<T: Into<OwnedFd>>(&mut self, fd: T) -> io::Result<()>;

    fn replace_fd<T: Into<OwnedFd>>(&mut self, replace_with: T) -> io::Result<OwnedFd>;

    fn take_fd(&mut self) -> io::Result<OwnedFd>;
}

// windows
pub trait StdioExt {
    fn set_handle<T: Into<OwnedHandle>>(&mut self, handle: Option<T>) -> io::Result<()>;

    fn replace_handle<T: Into<OwnedHandle>>(&mut self, replace_with: T) -> io::Result<Option<BorrowedHandle<'static>>>;

    fn take_handle(&mut self) -> io::Result<Option<BorrowedHandle<'static>>>;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• ACP: rust-lang/libs-team#500
• #150668
• #159312
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• The windows API leaks the old handles handles because they're
  essentially BorrowedHandle<'static> and might be in use by other threads.
  This can lead to pipes not getting closed, which may be unexpected.
  #t-libs > take, close and replace for stdio

Start by reviewing the StdioExt public API and the completed ACP, #150668, and #159312 steps. Read the linked Zulip discussion about Windows handle ownership; the tracking work is done when the unresolved handle behavior is resolved, followed by the final comment period and stabilization PR.