rust/src/test/compile-fail/issue-21763.rs

// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Regression test for HashMap only impl'ing Send/Sync if its contents do

use std::collections::HashMap;
use std::rc::Rc;

fn foo<T: Send>() {}

fn main() {
    foo::<HashMap<Rc<()>, Rc<()>>>();
    //~^ ERROR: the trait `std::marker::Send` is not implemented for the type `std::rc::Rc<()>`
}