rust-chg: add project skeleton This directory will host the reimplementation of cHg in Rust. It will use Tokio [1], and tokio-hglib [2] which I wrote for an oxidized CHg, no idea if there's such carbon bonding in nature btw. [1]: https://tokio.rs/ [2]: https://bitbucket.org/yuja/tokio-hglib/ The reasoning for depending on Tokio is that it will allow us to handle Unix signals in a safer way. Well, I believed that until I found a weird function, handlestopsignal(), in cHg codebase. It resends the same signal to the same process by temporarily masking the handler, which can't be inherently async. So the signal handlers will stay in C, which means there isn't actually much reason to write async code right now, other than I've already done most of the async stuff, and slightly easier pager handling. The reasoning for the rewrite is that it will eventually be possible to port server-side config validation back to the client side, which will reduce the complexity of the current daemon management. It will also encourage us to write frontend library (e.g. command line and config parsers) in Rust. The license is GPL2+ because it's likely to include derived work from the cHg of C. The rust/chg crate is excluded from the root workspace as it's unclear how the whole rust packages should be laid out. That can be revisited later.

narrow: move copies overrides to core The copies overrides seems to have been a little complicated just by not being in core. When moved to core, it becomes trivial (at least I think these overrides have the same effect). Differential Revision: https://phab.mercurial-scm.org/D4825

narrow: pass old includes and excludes to _widen() In future patches we will need to pass them in the widen wireprotocol command which we are building. Differential Revision: https://phab.mercurial-scm.org/D4812

narrow: check for servers' narrow support before doing anything (BC) Recently we introduced narrow capabilities for the server. So we can check whether a server has narrow clone support or not before doing anything. This is BC because new clients won't be able to extend from old narrow-enabled servers. I *think* narrow is not used much (maybe just inside Google), also it's experimental so I think we can change this. We will need to this someday anyway. The "doesn't" in error is changed to "does not" because I think that's we do in core. I also changed one more instance of the error message to use 'does not' for consistency. Differential Revision: https://phab.mercurial-scm.org/D4789

narrow: don't do the dirstate dance if ellipses is not enabled I believe we set dirstate parents to nullid before widening pull because in ellipses cases, the parent might be stripped off with a new changeset. However the second ds.setparents() call invalidate my assumption. I am not sure why we do this. So here is a patch. This patch also adds tests showing we break nothing in non-ellipses cases. Differential Revision: https://phab.mercurial-scm.org/D4788

narrow: pass 'narrow_widen' as source while generating changegroup Extensions inspect the `source` parameter and add some custom logic on the basis of value of that parameter. The parameter is also passed to hooks. So let's pass the value as 'narrow_widen' to differentiate widening from pull. Differential Revision: https://phab.mercurial-scm.org/D4787

narrow: factor out logic to create cg while widening into separate fn This patch takes out the logic which generates a changegroup for widening a narrow clone when ellipses are disabled. This is done because future patches will introduce a narrow_widen() wireprotocol command which will send a bundle2 with changegroup and will use this function. The new function for now returns just the changegroup for compatibility with existing code, but in future patches, when we establish a wireprotocol command and call this function from there, this will return the required bundle2. Differential Revision: https://phab.mercurial-scm.org/D4786

narrow: avoid looking up dirstate again when editing dirstate The narrow extension overrides the dirstate editing functions to restrict paths outside the narrowspec. These overrides access the dirstate from repo.dirstate instead of using the "self" reference passed to the overridden functions. I don't see a reason for this and it caused me problems with a later patch (it caused infinite recursion when I modified localrepo.dirstate()), so let's change it. Differential Revision: https://phab.mercurial-scm.org/D4829

repo: move unfiltered-repo optimization to workingctx localrepo.__getitem__ special-cased lookup of the working copy parent to avoid looking up obsmarkers. I think the reason for that code (which I once wrote myself) was to make `hg commit` not load obsmarkers, which it would otherwise do via ctx.p1() in localrepo.commitctx(). That had the somewhat unfortunate consequence of making lookup of an unrelated binary nodeid load the dirstate. Now that changectx's constructor is dumb, we can let workingctx._parents() have the opmtimization instead. This affects two tests, because they no longer end up loading the dirstate and their "warning: ignoring unknown working parent ..." messages therefore go way. Differential Revision: https://phab.mercurial-scm.org/D4828

context: move logic from changectx.__init__ to localrepo.__getitem__ (API) My motivation for this change was to make repo[node] not load the dirstate (more about that in the next patch), but I think it makes more sense this way too. For example, raising RepoLookupError seems to belong better in the repo lookup function (i.e. localrepo.__getitem__). This makes the changectx constructor very simple -- it just assigns the given repo, revnum, and nodeid to properties. Differential Revision: https://phab.mercurial-scm.org/D4827