rust/hg-core/src/dirstate.rs

rust: bump to memmap2 0.5.3, micro-timer 0.4.0, and crossbeam-channel 0.5.0

The merge in 12adf8c695ed had conflicts in rust/Cargo.lock and
rust/hg-core/Cargo.toml . Let's ignore rust/Cargo.lock - it is regenerated.

For rust/hg-core/Cargo.toml, stable had dd6b67d5c256 "rust: fix unsound
`OwningDirstateMap`" which introduced ouroboros (and dropped
stable_deref_trait).

Default had ec8d9b5a5e7c "rust-hg-core: upgrade dependencies" which had a lot
of churn bumping minimum versions - also patch versions. It is indeed a good
idea to bump to *allow* use of latest package. That means that major versions
should be bumped for packages after 1.0, and for packages below 1.0 minor
versions should be bumped too. But it doesn't work to try enforce a policy of
using latest patch by bumping versions at arbitrary times.

For good or bad, the merge doesn't seem to have resolved the conflicts
correctly, and many of the minor "upgrade dependencies" were lost again.

Unfortunately, it also lost the bump of memmap2 to 0.5.3, which is needed for
Fedora packaging where 0.4 isn't available. Same with micro-timer bump to 0.4
(which already is used in rhg). crossbeam-channel bump was also lost.

This change fixes that regression by redoing these "important" lines of the
merge "correctly".

I propose this for stable, even though dependency changes on stable branches
are annoying.

// dirstate module
//
// Copyright 2019 Raphaël Gomès <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

use crate::dirstate_tree::on_disk::DirstateV2ParseError;
use crate::revlog::node::NULL_NODE;
use crate::revlog::Node;
use crate::utils::hg_path::HgPath;
use bytes_cast::BytesCast;

pub mod dirs_multiset;
pub mod entry;
pub mod parsers;
pub mod status;

pub use self::entry::*;

#[derive(Debug, PartialEq, Copy, Clone, BytesCast)]
#[repr(C)]
pub struct DirstateParents {
    pub p1: Node,
    pub p2: Node,
}

impl DirstateParents {
    pub const NULL: Self = Self {
        p1: NULL_NODE,
        p2: NULL_NODE,
    };
}

pub type StateMapIter<'a> = Box<
    dyn Iterator<
            Item = Result<(&'a HgPath, DirstateEntry), DirstateV2ParseError>,
        > + Send
        + 'a,
>;

pub type CopyMapIter<'a> = Box<
    dyn Iterator<Item = Result<(&'a HgPath, &'a HgPath), DirstateV2ParseError>>
        + Send
        + 'a,
>;