log: move miscellaneous filter/matcher options to walkopts Maybe this is the most uninteresting patch. I want to remove the dependency on untyped/unlabeled opts dict at all. I thought --no-merges and --only-merges could be merged into a single enum value, but actually they both can be set to filter out everything.

log: map --removed to walkopts.force_changelog_traversal This is the flag to forcibly enable the slowpath. I'm not sure if the slowpath parameter should be merged with this flag, so let's keep it as an immutable flag for now. I'll add another flag to support "grep --all-files". These two will be the flags which aren't directly mapped from the command-line options.

copies: rename some function to the new naming scheme We are about to introduce more function and more variants, it seems better to align everything on the new scheme, allowing `_` for clarify. We do this aligned in a dedicated changeset to make the next changesets simpler. Differential Revision: https://phab.mercurial-scm.org/D9113

changing-files: cache the various property We are going to start using them more having some basic caching would be good. The focus is not about performance yet, however avoid some easy N² trap seems reasonable. Differential Revision: https://phab.mercurial-scm.org/D9112

changing-files: always use `mark_touched` to update the touched set We use this function internally too because that will make cache invalidation simpler. Differential Revision: https://phab.mercurial-scm.org/D9111

changing-files: fix docstring As pointed by Pulkit Goyal. Differential Revision: https://phab.mercurial-scm.org/D9143

rust: move rustfmt.toml to repo root so it can be used by `hg fix` `hg fix` runs the formatters from the repo root so it doesn't pick up the `rustfmt.toml` configs we had in each the `hg-core`, `hg-cpython`, and `rhg` packages, which resulted in warnings about `async fn` not existing in Rust 2015. This patch moves the `rustfmt.toml` file to the root so `hg fix` will use it. By putting the `rustfmt.toml` file in a higher-level directory, it also applies to the `chg` and `hgcli` packages. That makes `test-check-rust-format.t` fail, so this patch also applies the new formatting rules to those packages. Differential Revision: https://phab.mercurial-scm.org/D9142

merge: if CHANGED_DELETED and KEEP_NEW are actions, choose CHANGED_DELETED ACTION_KEEP_NEW and ACTION_CHANGED_DELETED are conflicting actions as one says that file is new while other says that file was present earlier and has changed-delete conflicts. Let's do changed-delete which will lead to conflicts and make user choose the right way.

tests: fix a typo in `desc()` revset in test-merge-criss-cross.t I was looking into fixing the broken behavior only to find out that we had a typo in the commit message and merge was not performed.

merge: if DELETED_CHANGED and GET are in actions, choose DELETED_CHANGED ACTION_GET represents that either the file is created on remote or it's newer on the remote side. However, since we have a ACTION_DELETE_CHANGED too, it means the file is not present locally and ACTION_GET is representing that file was created on remote. Having both ACTION_GET and ACTION_DELETED_CHANGED is conflicting because one says that file was created on remote and other says file has delete-changed conflicts. Let's choose ACTION_DELETED_CHANGED which will result in conflicts and make user choose the right way forward.

tests: add newfilenode test case in test-merge-changedelete.t

rust: leverage improved match ergonomics Differential Revision: https://phab.mercurial-scm.org/D9137

rust: update minimum supported Rust compiler version Debian stable backported `rustc 1.41.1` for a Firefox release that needed it, so we can finally update the compiler version to something that isn't more than a year old. This means that (among other things [1]), `async await` syntax is usable! Differential Revision: https://phab.mercurial-scm.org/D9138

changing-files: add a utility to compute the merged files post-commit We will need it in `_getsidedata` as soon as we start persisting that set. Differential Revision: https://phab.mercurial-scm.org/D9089

changing-files: record merged files at commit time The data is easy to gather at commit time, and we need it for changeset centric copy tracing. Right now, it is not persisted so we cannot use it. However we will fix this part very soon, gathering something to persist was necessary first. Differential Revision: https://phab.mercurial-scm.org/D9088

changing-files: add the ability to track merged files too The set of merged files is used when doing changeset centric copy tracing (cf `is_merged` in `mercurial/copies.py`. So tracking (and persisting) this set will be useful. We start with adding the attribute on the new object. Differential Revision: https://phab.mercurial-scm.org/D9087

rust: start plugging the dirstate tree behind a feature gate The previous patch added the `dirstate-tree` feature gate to enable the two dirstate implementations to co-habit while the tree-based one gets better. This patch copies over the code that differs, be it because the algorithm changed or because the borrowing rules are different. Indeed, `DirstateTree` is not observationally equivalent to the std `HashMap` in the APIs we use: it does not have the `Entry` API (yet?) and its iterator returns owned values instead of references. This last point is because the implementation needs to be changed to a more clever and efficient solution. Differential Revision: https://phab.mercurial-scm.org/D9133

rust: introduce `dirstate-tree` cargo feature This feature gates (at compile-time) the use of the newly-added dirstate tree. The motivation for this is that the dirstate tree is currently *very* slow; replacing the current hashmap-based dirstate is not a viable solution in terms of performance... and why would you be using the Rust implementation if not for performance? The feature will also help reviewers better understand the differences that will slowly appear as the dirstate tree gets better. Differential Revision: https://phab.mercurial-scm.org/D9132

rust: fix formatting Maybe there is a small divergence in the nightly formatter? This didn't seem to trip the CI. Differential Revision: https://phab.mercurial-scm.org/D9131

rust-matchers: make `Matcher` trait object-safe Before this patch, it is not possible to create a `Matcher` trait-object (like `Box<dyn Matcher>`), because of the use of a generic parameters in some methods, namely `impl AsRef<HgPath>`. While this makes the interface less flexible for callers in theory, it does not change anything in the current codebase. Until something like [1] is implemented, this is a "tradeoff" that we need to make anyway. [1] https://internals.rust-lang.org/t/pre-rfc-expand-object-safety/12693 Differential Revision: https://phab.mercurial-scm.org/D9071

rust: clippy pass This removes some justified warnings and one hard error that, while technically not a bug, was an ugly oversight on my part. Differential Revision: https://phab.mercurial-scm.org/D9094

updaterepo: add deprecation warning We just moved all in-tree callers off of the function, but we're leaving it here for a bit to help extension writers. Differential Revision: https://phab.mercurial-scm.org/D9110

rhg: use `.or(Err(Error))` not `.map_err(|_| Error)` (D9100#inline-15067) Differential Revision: https://phab.mercurial-scm.org/D9109

hg-core: use `.or(Err(Error))` not `.map_err(|_| Error)` (D9100#inline-15067) Differential Revision: https://phab.mercurial-scm.org/D9108