| // Copyright 2013 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. |
| |
| |
| /*! |
| * C-like enums have to be represented as LLVM ints, not wrapped in a |
| * struct, because it's important for the FFI that they interoperate |
| * with C integers/enums, and the ABI can treat structs differently. |
| * For example, on i686-linux-gnu, a struct return value is passed by |
| * storing to a hidden out parameter, whereas an integer would be |
| * returned in a register. |
| * |
| * This test just checks that the ABIs for the enum and the plain |
| * integer are compatible, rather than actually calling C code. |
| * The unused parameter to `foo` is to increase the likelihood of |
| * crashing if something goes wrong here. |
| */ |
| |
| #[repr(u32)] |
| enum Foo { |
| A = 0, |
| B = 23 |
| } |
| |
| #[inline(never)] |
| extern "C" fn foo(_x: usize) -> Foo { Foo::B } |
| |
| pub fn main() { |
| unsafe { |
| let f: extern "C" fn(usize) -> u32 = ::std::mem::transmute(foo); |
| assert_eq!(f(0xDEADBEEF), Foo::B as u32); |
| } |
| } |