rust-matchers: add `Matcher` trait and implement `AlwaysMatcher` In our quest of a faster Mercurial, we have arrived at the point where we need to implement the matchers in Rust. This RFC mainly for the `Matcher` trait to see if the changes proposed feel fine to people with more experience on the matter. While the `AlwaysMatcher` implementation is here as a trivial example, it should be the first step towards matchers use in Rust as it is currently the only supported one. Notable changes: - `exact` is renamed to `exact_match` - enums for `visit*` methods with `Recursive` instead of `'all'`, etc. - a new `roots`, separate from `file_set` - no `bad`, `explicitdir` or `traversedir` functions as they can be passed to the high functions instead of the matchers Thanks to Martin for suggesting the last two (most important) changes and for reaching out to help a few weeks ago. Differential Revision: https://phab.mercurial-scm.org/D7178

merge with stable

perf: add a way to benchmark `dirstate.status` Getting more details about time spend in this specific internal bit is meaningful.

largefiles: delete obsolete and unused repo.push() The function was removed from localrepo in 4d52e6eb98ea (locarepo: remove the `push` method (API), 2014-09-25). Differential Revision: https://phab.mercurial-scm.org/D7174

censor: document that some commands simply ignore censored data I can't see a benefit for hg grep to ever error out early when it encounters censored data.

grep: warn on censored revisions instead of erroring out We need most of the grep logic to go through in case we encounter a censored revision, so we just return a None body for a censored node, and we stop just short of trying to record matches with the contents of that censored body. The other parts such as recording that the censored file has been considered at this revision needs to go into the proper dicts. I have also gotten weary of all the abbreviations, so while I did a small refactor to move the file-data-getting operation into a common function, I also expanded the abbreviations of the relevant variables within this little function. Hopefully some day this helps someone figure out what all the abbreviations mean. Although the censoring docs currently state that some commands error out or are ignored depending on the `censor.policy` config, I cannot see a benefit for grep to ever stop dead in its tracks when a censored revision is encountered. I will also amend the docs to indicate that some commands, such as grep, unconditionally ignore censored revisions.

py3: enable legacy fs encoding to fix filename compatibility on Windows This patch is untested. I just followed the instruction: https://docs.python.org/3/whatsnew/3.6.html#pep-529-change-windows-filesystem-encoding-to-utf-8

rust-cpython: run cargo fmt

rust-cpython: remove useless PyResult<> from leak_immutable() The caller should know if the shared data is mutably borrowed or not.

rust-cpython: remove useless PyRefMut wrapper

rust-cpython: drop manual management of mutably_borrowed RefCell::borrow() should guarantee there's no mutable borrow. As a follow up, maybe PySharedState can be a pure data structure + function. Most ref-sharing business has already been moved to PySharedRef* and PyLeaked*.

rust-cpython: leverage RefCell::borrow() to guarantee there's no mutable ref Since the underlying value can't be mutably borrowed by PyLeaked, we don't have to manage yet another mutably-borrowed state. We can just rely on the RefCell implementation. Maybe we can add try_leak_immutable(), but this patch doesn't in order to keep the patch series not too long.