Function std::old_io::stdio::set_stderrUnstable

pub fn set_stderr(stderr: Box<Writer + Send>) -> Option<Box<Writer + Send>>

Resets the task-local stderr handle to the specified writer

This will replace the current task's stderr handle, returning the old handle. Currently, the stderr handle is used for printing panic messages during task panic.

Note that this does not need to be called for all new tasks; the default output handle is to the process's stderr stream.