modinfo needs a const char [], not a const char *

[geofft]

We use this (from src/lib.rs) to set modinfo:

#[link_section = ".modinfo"]
#[allow(non_upper_case_globals)]
// TODO: Generate a name the same way the kernel's `__MODULE_INFO` does.
// TODO: This needs to be a `[u8; _]`, since the kernel defines this as a  `const char []`.
// See https://github.com/rust-lang/rfcs/pull/2545
pub static $name: &'static [u8] = concat!(stringify!($name), "=", $value, '\0').as_bytes();

This (likely) stores a pointer to a string in the modinfo section instead of storing the string directly.

[geofft]

I'm having a real hard time turning the output of str::as_bytes into a [u8; N]. If I compile

#[link_section = ".modinfo"]
pub static FOO: [u8; 11] = b"Hello world";

with rustc --crate-type=dylib and do an objdump -s -j .modinfo on it, it works great. And I can even type it as [u8; b"Hello world".len()] (with #![feature(const_slice_len)]). If I try to do anything involving "Hello world".as_bytes() I get into endless difficulty trying to coerce a [u8] to a [u8; N]. So even if we got rust-lang/rfcs#2545 it wouldn't help that much. :(

Maybe the right strategy is to tackle this and #16 at the same time, switch to bytes instead of strings as input, and adopt e.g. https://github.com/danielhenrymantilla/byte-strings-rs which uses proc macros to implement concat_bytes!etc. Then the macro is probably something like

pub static $name: [u8; c_str!(as_bytes!(stringify!($name), b"=", as_bytes!($value)).len()]
                     = c_str!(as_bytes!(stringify!($name), b"=", as_bytes!($value));