Crate infer_len

“Infer” the lengths of arrays in static /const items.

Crate feature

• no-core: Make this crate #![no_core].

  #![no_core] example

  #![feature(no_core, lang_items, start)]
  #![no_core]
  
  #[cfg_attr(not(windows), link(name = "c"))]
  #[cfg_attr(windows, link(name = "msvcrt"))]
  extern "C" {}
  
  use infer_len::infer_len;
  
  #[lang = "sized"]
  trait Sized {}
  
  #[lang = "eh_personality"]
  fn eh_personality() -> ! {
      loop {}
  }
  
  #[lang = "receiver"]
  trait Receiver {}
  
  impl<T: ?Sized> Receiver for &T {}
  
  #[lang = "array"]
  impl [i32; 5] {
      const fn len(&self) -> usize {
          5
      }
  }
  
  infer_len! {
      const FOO: [i32] = [1, 2, 3, 4, 5];
      const BAR: [i32] = [6, 7, 8, 9, 10];
  }
  
  #[start]
  fn main(_: isize, _: *const *const u8) -> isize {
      let _: [i32; 5] = FOO;
      let _: [i32; 5] = BAR;
      0
  }

Example

use std::convert;

infer_len! {
    pub(self) const FOO: [i128] = [-1, -2, -3, -4];
    const BAR: [i128] = FOO;
    pub static BAZ: [i128] = BAR;
    #[allow(non_upper_case_globals)] // attribute works
    static qux: [i128] = convert::identity(BAR); // arbitrary expression works
    #[allow(non_upper_case_globals)]
    #[used] // multiple attributes works
    static used: [i128] = FOO;
}

let _: [i128; 4] = FOO;
let _: [i128; 4] = BAR;
let _: [i128; 4] = BAZ;
let _: [i128; 4] = qux;

Macros

infer_len

The main macro of this crate.