`with_file_name` doesn't provide checks for "path filenames"

Filenames which include paths are not being treated properly by with_file_name in the Path library. Filenames which include ".." and other similar components are treated as part of the path. For example, consider:

use std::fs::File;
use std::path::Path;

fn main() {
    let pathtest = "test/hey.txt";
    let name = r"../gotu.txt";
    let path = Path::new(pathtest);
    let actual_path = path.with_file_name(name);

    File::create(actual_path).unwrap();
}

It will create "gotu.txt" at the parent directory, which could lead to potential security issues (creating files at unintended directories).

Solutions

Change the current behavior

Changing the implementation which will includes checks for this kind of behavior. (A very easy fix.)

Change the documentation

Include an example, a fix or a warning about this behavior in the documentation.

Start by reading the Path::with_file_name entry point, its implementation, and its existing documentation. Determine whether the project wants changed path handling or an explicit warning/example, then identify the relevant test location and define done as covering the reported path-filename behavior.