小编ber*_*oal的帖子

根据文档：

pub const unsafe extern "C" fn CMSG_SPACE(length: c_uint) -> c_uint

但是，如果我编译

fn main() {
    let _ = [0u8; libc::CMSG_SPACE(1) as usize];
}

我收到以下错误：

error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants
 --> src/bin/libc-const.rs:2:27
  |
2 |     let _ = [0u8; unsafe {libc::CMSG_SPACE(1) as usize}];
  |                           ^^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0015`.