AtomicBitSet Debug crashes

[funnisimo]

This crashes...

use hibitset::AtomicBitSet;

fn main() {
    let bitset = AtomicBitSet::new();
    println!("bitset = {:?}", bitset);
}

The proposed fix implements Debug for AtomicBlock so that the error doesn't happen - please check the output to make sure it is what you want it to be for internal debugging.
It also implements AtomicBitSet Debug manually to be the output of iter() - which I felt was more helpful to users of the library.

[Imberflur]

Hi! Thank you for fixing this crash.

I left some suggestions on the AtomicBlock debug implementation.

[Imberflur]

fetch_or will modify the value, I think we just want load here?

[Imberflur]

commented debug derive can be removed

[Imberflur]

A helper type could be used here to avoid the allocation when collecting into a vec:

Suggested change

	let mut s = f.debug_struct("AtomicBlock");
	s.field("mask", &self.mask);
	if let Some(atom) = self.atom.get() {
	s.field(
	"atom",
	&atom
	.iter()
	.enumerate()
	.filter_map(|(idx, v)| match v.fetch_or(0, Ordering::Relaxed) {
	0 => None,
	x => Some((idx, x)),
	})
	.collect::<Vec<(usize, usize)>>(),
	);
	}
	struct DebugAtom<'a>(&'a [AtomicUsize; 1 << BITS]);
	impl Debug for DebugAtom<'_> {
	fn fmt(&self, f: &mut Formatter) -> Result<(), FormatError> {
	f.debug_list()
	.entries(self.0.iter().enumerate().filter_map(|(idx, v)| {
	match v.load(Ordering::Relaxed) {
	0 => None,
	x => Some((idx, x)),
	}
	}))
	.finish()
	}
	}
	let mut s = f.debug_struct("AtomicBlock");
	s.field("mask", &self.mask);
	if let Some(atom) = self.atom.get() {
	s.field("atom", &DebugAtom(atom));
	}

[Imberflur]

if this returns None I think we would still want the formatting to show that an atom field exists

e.g. in the None case perhaps it could be:

s.field("atom", &"None");

or following from my other comment to use a helper type we could do:

s.field("atom", &self.atom.get().map(DebugAtom));