rust-chg: upgrade to 2018 edition and remove useless extern crates Differential Revision: https://phab.mercurial-scm.org/D8399

mergestate: store about files resolved in favour of other Committing a merge sometimes wrongly creates a new filenode where it can re-use an existing one. This happens because the commit code does it's own calculation and does not know what happened on merge. This starts storing information in mergestate about files which were automatically merged and the other/remote version of file was used. We need this information at commit to pick the filenode parent for the new commit. This issue was found by Pierre-Yves David and idea to store the relevant parts in mergestate is also suggested by him. Somethings which can be further investigated are: 1) refactoring of commit logic more to depend on this information 2) maybe a more generic solution? Differential Revision: https://phab.mercurial-scm.org/D8392

histedit: add test that an invalid editor doesn't bork client state We had a report of a situation like this borking a user at Google, but I can't reproduce it in a test. Let's at least backstop the issue with a test, so we don't accidentally introduce such a bug... Differential Revision: https://phab.mercurial-scm.org/D8391

rust-chg: silence warning about dated coding style Differential Revision: https://phab.mercurial-scm.org/D8384

rust-chg: update name of the server process This is a copy of updateprocname() of hgclient.c. At this point, rust-chg is basically functional. I did dogfooding for a couple of weeks in 2018. There are a few remaining tasks: a. loop detection by CHGINTERNALMARK b. forward unsupported commands (notably serve -d) to real hg c. better handling of early server exception d. modernize codebase (2018 edition, impl trait, async/await) For (d), we'll probably want to switch to async-std, but I'm thinking of upgrading to Tokio 0.2 as an intermediate step since process API isn't ported to async-std yet. I'm pretty sure future migration to async-std will be painless compared to the mass rewrite from futures-0.1 to 0.3. https://github.com/async-rs/async-std/issues/22 Differential Revision: https://phab.mercurial-scm.org/D8383

rust-chg: send client side umask to server This is equivalent to forwardumask() of hgclient.c. Differential Revision: https://phab.mercurial-scm.org/D8382

rust-chg: add config validation and process returned instructions This is the reimplementation of runinstructions() and main() in chg.c. In Rust version, we only pass in early arguments to the server as the locator doesn't know the full arguments. This should be fine since these arguments are just passed in to _earlyparseopts() and _parseconfig(), which means the server doesn't need full arguments. Another difference is the handling of the "exit <code>" instruction. In Rust version, we can simply reuse the connection instead of "exit(code)" as the command error isn't displayed yet. That's because the client-side stdio is not attached until the connection is validated. This behavior is cleaner than C, but it also means that the early server exception wouldn't be propagated to client because stderr isn't attached. So we might have to reconsider when to attach/detach the server stdio. Differential Revision: https://phab.mercurial-scm.org/D8381