ring/polyfill/
unwrap_const.rs

1// Copyright 2022 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15/// Polyfill for `Option::unwrap()` as a const fn; feature `const_option`.
16/// https://github.com/rust-lang/rust/issues/67441.
17/// TODO(MSRV): Replace this with `x.unwrap()`.
18///
19/// `T: Copy` avoids "constant functions cannot evaluate destructors."
20pub const fn unwrap_const<T>(x: Option<T>) -> T
21where
22    T: Copy,
23{
24    if let Some(x) = x {
25        x
26    } else {
27        panic!("unwrap_const on `None`");
28    }
29}