rust: fix unsound `OwningDirstateMap` As per the previous patch, `OwningDirstateMap` is unsound. Self-referential structs are difficult to implement correctly in Rust since the compiler is free to move structs around as much as it wants to. They are also very rarely needed in practice, so the state-of-the-art on how they should be done within the Rust rules is still a bit new. The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense) of declaring self-referential structs. It is getting a lot attention and was improved very quickly when soundness issues were found in the past: rather than relying on our own (limited) review circle, we might as well use the de-facto common crate to fix this problem. This will give us a much better chance of finding issues should any new ones be discovered as well as the benefit of fewer `unsafe` APIs of our own. I was starting to think about how I would present a safe API to the old struct but soon realized that the callback-based approach was already done in `ouroboros`, along with a lot more care towards refusing incorrect structs. In short: we don't return a mutable reference to the `DirstateMap` anymore, we expect users of its API to pass a `FnOnce` that takes the map as an argument. This allows our `OwningDirstateMap` to control the input and output lifetimes of the code that modifies it to prevent such issues. Changing to `ouroboros` meant changing every API with it, but it is relatively low churn in the end. It correctly identified the example buggy modification of `copy_map_insert` outlined in the previous patch as violating the borrow rules. Differential Revision: https://phab.mercurial-scm.org/D12429

rust: explain why the current `OwningDirstateMap` is unsound See inline comments. Differential Revision: https://phab.mercurial-scm.org/D12428

dispatch: fix silly blackbox entries when hg is interrupted When hg is interrupted, it creates ui.log like this: 1970/01/01 00:00:00 user @0000000000000000000000000000000000000000 (62488)> killed! exited 255 after 1.78 seconds This is due to a scoping problem: two different uses of the name "msg" collide. So rename one of them. Differential Revision: https://phab.mercurial-scm.org/D12427

tests: stop excluding the pycompat module from pyflakes I assume this was skipped because of all of the py2 stuff causing a lot of spew. The "unused" imports are left in place in case any 3rd party stuff is using it. I don't care about most of it, but TortoiseHg uses `io` and `queue`, so minimally I'd like to keep those. Differential Revision: https://phab.mercurial-scm.org/D12423

tests: drop some py2 specific pyflake failures Differential Revision: https://phab.mercurial-scm.org/D12422

util: drop a duplicate import This was already imported several lines above. Differential Revision: https://phab.mercurial-scm.org/D12421

pycompat: drop the pickle import I suspect this is what df56e6bd37f6 meant to eliminate. Differential Revision: https://phab.mercurial-scm.org/D12420

util: restore the util.pickle symbol This was accidently dropped in df56e6bd37f6, which started importing pickle directly. That commit explicitly says it will retain it for compatibility with external stuff though. The unused import in pycompat isn't flagged because that module is skipped. Just importing with a comment seemed cleaner than `import X as Y` and then assigning to a `pickle` variable, just to avoid the pyflakes warning. Differential Revision: https://phab.mercurial-scm.org/D12419

merge: stable into default

precheck: fix false warning about content-divergence creation Before this patch, if we try to `hg prune` (without any successors) an already obsoleted cset which has at least one successor, it would false warn about new content-divergence. As we know, pruning cset without any successors can not create any divergence. Differential Revision: https://phab.mercurial-scm.org/D12002

streamclone: avoid some obscure error in a corner case I don't really know how, but I ran into this error: $ hg clone --stream ssh://user@dummy/empty-repo local-empty-repo streaming all changes abort: unable to apply stream clone: unsupported format: [255] I think you need an empty list of requirements for this to happen, which is weird, but an obscure error like this is not exactly helpful either. Since this is the result of an encoding bug anyway, just fix it. Differential Revision: https://phab.mercurial-scm.org/D12402

tags: fix typo in fast path detection of fnode resolution (issue6673) If I understand it, mctx.readfast() is unreliable here if p1/p2 .hgtags nodes differ, and tags on that branch would be randomly discarded depending on which parent were picked. The test case added by this patch would fail only on zstd-compressed repository. I didn't try hard to stabilize the failure case.

completion: install completers to conventional locations Installs the bash and zsh completers to the convential locations so they will automatically be picked up without user intervention. The zsh completer on Debian is still installed to vendor-completions to match their policy. bash: https://github.com/scop/bash-completion#faq zsh: https://github.com/zsh-users/zsh/blob/57305cf245853b8b30895b41a90142dffab97e38/INSTALL#L254 Debian zsh: https://salsa.debian.org/debian/zsh/-/blob/5086b5356abcef8849dc8a09902b7c55f01db3c0/debian/README.Debian#L73

dirstate-cext: properly invalidate mtime and data in `set_untracked` This was forgotten about in the initial implementation and was revealed while adding the `dirstate-v2` variant of `test-issue660.t`. Neither the existing Python implementation nor the upcoming Rust implementation suffer from this bug since they respectively have `None` and `Option<T>` to represent the lack of information. Differential Revision: https://phab.mercurial-scm.org/D12414

pytype: disable a few errors about Windows specific module attributes These were flagged by pytype 2022.03.21. Differential Revision: https://phab.mercurial-scm.org/D12401

rhg: sort unsupported extensions in error message This caused some flakiness in test output, and is also just better for users. Differential Revision: https://phab.mercurial-scm.org/D12389

hgignore: ignore .testtimes in more location See the inline comment. Differential Revision: https://phab.mercurial-scm.org/D12393

merge: with stable

partial-merge: add support for `.args` config (`$local` etc.) It will be useful to be able to define custom command-line arguments per partial merge tool just like we have for regular merge tools. In particular, I expect the same binary to handle multiple languages, so it will be useful to be able to pass some argument indicating the language, or perhaps simply an argument defining a regex that's used for finding lines to merge as a sorted set. Differential Revision: https://phab.mercurial-scm.org/D12383

filemerge: add support for partial conflict resolution by external tool A common class of merge conflicts is in imports/#includes/etc. It's relatively easy to write a tool that can resolve these conflicts, perhaps by naively just unioning the statements and leaving any cleanup to other tools to do later [1]. Such specialized tools cannot generally resolve all conflicts in a file, of course. Let's therefore call them "partial merge tools". Note that the internal simplemerge algorithm is such a partial merge tool - one that only resolves trivial "conflicts" where one side is unchanged or both sides change in the same way. One can also imagine having smarter language-aware partial tools that merge the AST. It may be useful for such tools to interactively let the user resolve any conflicts it can't resolve itself. However, having the option of implementing it as a partial merge tool means that the developer doesn't *need* to create a UI for it. Instead, the user can resolve any remaining conflicts with their regular merge tool (e.g. `:merge3` or `meld). We don't currently have a way to let the user define such partial merge tools. That's what this patch addresses. It lets the user configure partial merge tools to run. Each tool can be configured to run only on files matching certain patterns (e.g. "*.py"). The tool takes three inputs (local, base, other) and resolves conflicts by updating these in place. For example, let's say the inputs are these: base: ``` import sys def main(): print('Hello') ``` local: ``` import os import sys def main(): print('Hi') ``` other: ``` import re import sys def main(): print('Howdy') ``` A partial merge tool could now resolve the conflicting imports by replacing the import statements in *all* files by the following snippet, while leaving the remainder of the files unchanged. ``` import os import re import sys ``` As a result, simplemerge and any regular merge tool that runs after the partial merge tool(s) will consider the imports to be non-conflicting and will only present the conflict in `main()` to the user. Differential Revision: https://phab.mercurial-scm.org/D12356

pullbundle: fix file name in the help text It is pullbundles.manifest and not pullbundle.manifest. Differential Revision: https://phab.mercurial-scm.org/D12391

unamend: abort if commit was not created by `hg [un]amend` `hg unamend` can currently undo any kind of rewrite, as long as it has an obsmarker. However, that has quite unexpected results if you run it after e.g. `hg rebase` (expecting it to behave like a generic `hg undo` command), because it updates to the predecessor and leaves the old changes in the working copy. I think it's better to allow `hg unamend` only after `hg amend` (and after `hg unamend` because that's documented as being supported). Differential Revision: https://phab.mercurial-scm.org/D12390

branching: merge stable into default

test: use `wait-on-file` in `test-racy-mutations.t` The official utility scale its timeout with the run-tests.py one. So lets use it. Differential Revision: https://phab.mercurial-scm.org/D12382

amend: fix amend with copies in extras If copy information is stored only in the commit extras and not in filelogs, then they get lost on amend if the file wasn't also modified in the working copy. That's because we create `filectx` object from the old commit in those cases, and the `.copysource()` of such objects read only from the filelog. This patch fixes it by always creating a new `memfilectx` in these cases, passing the calculated copy information to it. Differential Revision: https://phab.mercurial-scm.org/D12387

tests: demonstrate that copy info in changeset gets lost on amend When copy information is stored in changesets, it gets lost on amend. We didn't notice that until now because our users at Google have the config set to `compatibility`, which means copy information is stored in both changeset and filelogs. Differential Revision: https://phab.mercurial-scm.org/D12386

ci: use the `v1.0` flavor of the docker images in the CI This new versioning will help us to maintain backward compatibility in the docker image. This will be useful to deal with mismatch between default/stable in version and the re-run CI on older changesets in the future. Once this changeset land on stable, we will have to merge it in default. Then we can start make backward incompatible changes in a new image version. Differential Revision: https://phab.mercurial-scm.org/D12388

rust-status: cap the number of concurrent threads to 16 During benchmarking it was determined that the use of more threads is very advantageous... until we use more than 16. This is most likely due to some resource contention (thrashing, etc.). Until we have time to figure out and fix the underlying cause, let's just cap at 16 threads. Differential Revision: https://phab.mercurial-scm.org/D12384

rhg: add support for ignoring all extensions Some workflows just want what `rhg` does and don't care about any extensions, this makes it easier. Differential Revision: https://phab.mercurial-scm.org/D12385

branching: merge stable into default