rust-hg-path: add method to get part of a path relative to a prefix This will be used in the next patch in this series. Differential Revision: https://phab.mercurial-scm.org/D7526

rust-matchers: improve `Matcher` trait ergonomics `VisitChildrenSet` has no need to own the set, this will save allocations. The `file_set` return type change is motivated by both ergonomics and... being able to compile code. The `AlwaysMatcher` does not store a `file_set`, which requires it to return an owned `HashSet`, which in turn would change our return type to `Cow<&HgPath>` (lifetimes omitted). This is both un-ergonomic and troublesome for more complex lifetime issues (especially with the upcoming `FileMatcher` in the following patch). Differential Revision: https://phab.mercurial-scm.org/D7525

rust-dirs-multiset: use `AsRef` instead of concrete types when possible I also renamed `vec` to `dirstate`, because it was not a great name. Differential Revision: https://phab.mercurial-scm.org/D7524

logcmdutil: call _exthook() in changesettemplater Class changesetprinter has an _exthook() method that is called in _show() before the patch is displayed. Call the method as well in changesettemplater._show(). Differential Revision: https://phab.mercurial-scm.org/D7505

phabricator: fix processing of tags/desc in getoldnodedrevmap() It seems that the previous logic was wrong (it essentially comes from changeset 3ab0d5767b54 where the result got accumulated instead of early returned). First of all, the "continue" in first "if m:" is useless because we're at the end of the loop. Then, the algorithm seems weird because we will process all predecessors of a node and possibly override `toconfirm[node]` for each of these having a tag (maybe this doesn't happen, but still). Finally, we would also override `toconfirm[node]` when the "Differential Revision: " is found in changeset description. Maybe this is not a big deal when there is no mix of local tag and changeset description update? The logic is changed so that the loop on predecessors stops upon first match of a tag and so that the changeset description is only checked if no tag was found. Therefore, `toconfirm[node]` is only set once. Differential Revision: https://phab.mercurial-scm.org/D7513

tests: replace [[]] bashism with portable [] invocation In this case nothing fancy is required. Differential Revision: https://phab.mercurial-scm.org/D7596

rust-hg-path: implement `Display` for `HgPath` and `HgPathBuf` This is useful when debugging, to get a human readable output instead of an array of `u8`. Differential Revision: https://phab.mercurial-scm.org/D7523

rust-performance: introduce FastHashMap type alias for HashMap Rust's default hashing is slow, because it is meant for preventing collision attacks. For all of the current Rust code, we don't care about those attacks, because if an person with bad intentions has write access to your repo, you have other issues. I've chosen to use the TwoXHash crate because it was made by a reputable member of the Rust community and has very good benchmarks. For now it does not seem to improve performance by much for the current code, but it's something else to not worry about when benchmarking code: in a previous experiment with copytracing in Rust, it accounted for more than 10% of the time of the entire script. Differential Revision: https://phab.mercurial-scm.org/D7116

mail: use procutil.shellsplit instead of bytes.split to parse command Differential Revision: https://phab.mercurial-scm.org/D7541

annotate: describe --skip as taking a revset It's obvious to me, but probably wouldn't be obvious to a novice user. Differential Revision: https://phab.mercurial-scm.org/D7557