log: extract function that builds (revs, makefilematcher) from walkopts "hg grep" and "hg churn" will use this interface.

log: move --graph and topo sort options to walkopts This is the last opts.get() found in getrevs(). It might be better to define an enum, but for now, it is just a string.

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