Rust bindgen and systems/compilers where char is wider than 8 bits

Question

I have a C header file which contains string constants

#define SOLCLIENT_SESSION_PROP_USERNAME "SESSION_USERNAME"

and bindgen translates them to

pub const SOLCLIENT_SESSION_PROP_USERNAME: &'static [u8; 17usize] = b"SESSION_USERNAME\0";

(1) How will bindgen behave when C char is wider that 8 bits. Will it generate u16 array?

(2) If so how to consume the translated constants so my Rust code works both on systems where char is 8 bits and 16 bits. Currently I use std::ffi::CStr::from_bytes_with_nul() followed by .as_ptr() to convert these constants to *const c_char but that won't work because from_bytes_with_nul expects u8 slice.

IIRC, Rust only supports platforms where `CHAR_BIT` is 8. – hellow Nov 05 '21 at 12:11 — hellow, Nov 05 '21 at 12:11
What 16-bit-`char` system are you trying to run on? – Solomon Ucko Mar 14 '22 at 19:17 — Solomon Ucko, Mar 14 '22 at 19:17

score 1 · Answer 1 · answered Mar 14 '22 at 19:16

https://rust-lang.github.io/unsafe-code-guidelines/layout/scalars.html#char states: (emphasis added)

Note: Rust char type is not layout compatible with C / C++ char types. The C / C++ char types correspond to either Rust's i8 or u8 types on all currently supported platforms, depending on their signedness. Rust does not support C platforms in which C char is not 8-bit wide.

Rust bindgen and systems/compilers where char is wider than 8 bits

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