rust/src/test/compile-fail/const-fn-stability.rs

// Copyright 2015 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.

// Test use of const fn without feature gate.

const fn foo() -> usize { 0 } //~ ERROR const fn is unstable

trait Foo {
    const fn foo() -> u32; //~ ERROR const fn is unstable
    const fn bar() -> u32 { 0 } //~ ERROR const fn is unstable
}

impl Foo {
    const fn baz() -> u32 { 0 } //~ ERROR const fn is unstable
}

impl Foo for u32 {
    const fn foo() -> u32 { 0 } //~ ERROR const fn is unstable
}

static FOO: usize = foo();
const BAR: usize = foo();

fn main() {
    let x: [usize; foo()] = [];
}