Macro byte_strings::concat_bytes

macro_rules! concat_bytes {
    (
        $($expr:expr),+ $(,)?
    ) => { ... };
}

Concatenates byte string literals into a single byte string literal

This macro takes any number of comma-separated byte string literals, and evaluates to (a static reference to) a byte array made of all the bytes of the given byte string literals concatenated left-to-right.

Hence the macro evaluates to the type &'static [u8; N] (where N is the total number of bytes), which can also "be seen as" (coerce to) a static byte slice (i.e., &'static [u8]).

Arguments are not "byte-stringified".

Example

use ::byte_strings::concat_bytes;

let bytes = concat_bytes!(b"Hello, ", b"World!");
assert_eq!(bytes, b"Hello, World!");

Macro expansion:

For those curious, concat_bytes!(b"Hello, ", b"World!") expands to:

{
    const __byte_strings__concat_bytes: &'static [u8; 13usize] = b"Hello, World!";

    __byte_strings__concat_bytes
}

This trick is needed to circumvent the current restriction of procedural macros being able to expand to items only.