rand 0.9 beta error - isize: SampleUniform is not satisfied

[pendruct]

i used to be able to do rng.gen with isize but not anymore

[dhardy]

This is intentional: #1487.

Why do you need this?

[pendruct]

oh okay! so is this a breaking change then? i didnt see it mentioned in changelog but maybe im missing something.

i am making a game with a 2d maze and i use it for my teleport function:

fn teleport_destination_node(grid: &Grid, player_row: usize) -> Option<(usize, usize)> {
  let delta = roll(-2..13);
  let dest_row = player_row.saturating_add_signed(delta).clamp(0, grid.height.saturating_sub(1));

  for col in 0..grid.width {
    if grid.node(dest_row, col).is_main {
      return Some((dest_row, col));
    }
  }

  None
}

it's not that important though so i can just refactor it. thanks for the info!

im using usize and isize because im doing indexing into 2d arrays and thats what rust asks for

was able to get around it by doing this (since you can make an isize from an i16):

let delta: isize = roll(-2i16..13i16).into();

[dhardy]

Then I recommend you pick a fixed size integer like i16, yes.

The reason we did this was because of various complaints of a hidden portability hazard: generating a random usize / isize in rand v0.8 will produce different results on 32-bit and 64-bit machines.

It comes under this entry in the changelog, but you're right that it's unclear:

Add UniformUsize and use to make Uniform for usize portable (#1487)

[pendruct]

sure thing! thanks again for the replies! good luck with 0.9! looking forward to it!! 🥳