> +#[macro_export]
> +/// Given a string constant _without_ embedded or trailing NULs, return
> +/// a CStr.
> +///
> +/// Needed for compatibility with Rust <1.77.
> +macro_rules! c_str {
> + ($str:expr) => {{
> + const STRING: &str = concat!($str, "\0");
> + const BYTES: &[u8] = STRING.as_bytes();
> +
> + // "for" is not allowed in const context... oh well,
> + // everybody loves some lisp. This could be turned into
> + // a procedural macro if this is a problem; alternatively
> + // Rust 1.72 makes CStr::from_bytes_with_nul a const function.
> + const fn f(b: &[u8], i: usize) {
> + if i == b.len() - 1 {
> + } else if b[i] == 0 {
> + panic!("c_str argument contains NUL")
> + } else {
> + f(b, i + 1)
> + }
> + }
> + f(BYTES, 0);
> +
> + // SAFETY: absence of NULs apart from the final byte was checked
> above
> + unsafe { std::ffi::CStr::from_bytes_with_nul_unchecked(BYTES) }
> + }};
> +}
> +
It's not worth introducing the const_for crate for the loop, and I can't
come up with a better solution. The current implementation is simple and
effective, so for now, it's the best option for me.
Reviewed-by: Zhao Liu <[email protected]>
