contrib: a small script to nudge lingering diff After a discussion on IRC with various reviewers. It seems like a good idea to have some automatic cleanup of old, inactive diffs. Here is a small script able to do so. I am preparing to unleash it on our phabricator instance.

packaging: add support for PyOxidizer I've successfully built Mercurial on the development tip of PyOxidizer on Linux and Windows. It mostly "just works" on Linux. Windows is a bit more finicky. In-memory resource files are probably not all working correctly due to bugs in PyOxidizer's naming of modules. PyOxidizer now now supports installing files next to the produced binary. (We do this for templates in the added file.) So a workaround should be available. Also, since the last time I submitted support for PyOxidizer, PyOxidizer gained the ability to auto-generate Rust projects to build executables. So we don't need to worry about vendoring any Rust code to initially support PyOxidizer. However, at some point we will likely want to write our own command line driver that embeds a Python interpreter via PyOxidizer so we can run Rust code outside the confines of a Python interpreter. But that will be a follow-up. I would also like to add packaging.py CLI commands to build PyOxidizer distributions. This can come later, if ever. PyOxidizer's new "targets" feature makes it really easy to define packaging tasks in its Starlark configuration file. While not much is implemented yet, eventually we should be able to produce MSIs, etc using a `pyoxidizer build` one-liner. We'll get there... Differential Revision: https://phab.mercurial-scm.org/D7450

mergestate: add accessors for local and other nodeid, not just contexts The mergestate can contain invalid nodeids. In that case, `mergestate.localctx` or `mergestate.otherctx` will fail. This patch provides a way of accessing the nodeid without failing in such cases. Differential Revision: https://phab.mercurial-scm.org/D8040

rebase: define base in only place in defineparents() Just a little refactoring to prepare for the next patch. Differential Revision: https://phab.mercurial-scm.org/D7906

tests: use full `uncommit` command name in tests I'm about to add a `hg uncopy`, so the `hg unc` we used for `hg uncommit` would become ambiguous. Differential Revision: https://phab.mercurial-scm.org/D8028

graft: default `base` argument to common case of `ctx.p1()` I also updated the callers that wanted that, partly to simplify and partly to show that it works. Differential Revision: https://phab.mercurial-scm.org/D8027

graft: let caller pass in overlayworkingctx to merge.graft() Passing in a different `wctx` than `repo[None]` is useful because it allows the caller to decide to not touch the working directory. Differential Revision: https://phab.mercurial-scm.org/D8026

copies: fix crash when copy source is not in graft base Differential Revision: https://phab.mercurial-scm.org/D8046

tests: add test showing crash when shelving ghosted rename target When you `hg rename` a file and then delete the rename target, `hg shelve` will give you a traceback. Note that the shelve succeeds and the shelve is correct, it's just the update to the parent that fails (i.e. to the parent of the commit that was created for the shelve). This can be squashed into the next commit if the reviewer prefers. Differential Revision: https://phab.mercurial-scm.org/D8045

resourceutil: correct the root path for file based lookup under py2exe This silly copy/paste error caused "Mercurial" to be truncated from "C:\Program Files". The fact that "helptext" and "defaultrc" are now in a subpackage of "mercurial" added it back on, and everything seemed to work. But that broke if not installed to the default directory, and also caused TortoiseHg to look at Mercurial's config files instead of its own. Differential Revision: https://phab.mercurial-scm.org/D8054

rust-cpython: mark all PyLeaked methods as unsafe Unfortunately, these methods can be abused to obtain the inner 'static reference. The simplest (pseudo-code) example is: let leaked: PyLeaked<&'static _> = shared.leak_immutable(); let static_ref: &'static _ = &*leaked.try_borrow(py)?; // PyLeakedRef::deref() tries to bound the lifetime to itself, but // the underlying data is a &'static reference, so the returned // reference can be &'static. This problem can be easily fixed by coercing the lifetime, but there are many other ways to achieve that, and there wouldn't be a generic solution: let leaked: PyLeaked<&'static [_]> = shared.leak_immutable(); let leaked_iter: PyLeaked<slice::Iter<'static, _>> = unsafe { leaked.map(|v| v.iter()) }; let static_slice: &'static [_] = leaked_iter.try_borrow(py)?.as_slice(); So basically I failed to design the safe borrowing interface. Maybe we'll instead have to add much more restricted interface on top of the unsafe PyLeaked methods? For instance, Iterator::next() could be implemented if its Item type is not &'a (where 'a may be cheated.) Anyway, this seems not an easy issue, so it's probably better to leave the current interface as unsafe, and get broader comments while upstreaming this feature.

rust-cpython: make PySharedRef::try_borrow_mut() return BorrowMutError As I said, it shouldn't be an error of Python layer, but is something like a coding error. Returning BorrowMutError makes more sense. There's a weird hack to propagate the borrow-by-leaked state to RefCell to obtain BorrowMutError. If we don't like it, maybe we can add our own BorrowMutError.

rust-cpython: inline PySharedState::leak_immutable() and PyLeaked::new() For the same reason as the previous patch. The unsafe stuff can be better documented if these functions are inlined.

rust-cpython: inline PySharedState::try_borrow_mut() Since the core borrowing/leaking logic has been moved to PySharedRef* and PyLeaked*, it doesn't make sense that PySharedState had a function named "try_borrow_mut". Let's turn it into a pure data struct.

rust-cpython: add panicking version of borrow_mut() and use it The original borrow_mut() is renamed to try_borrow_mut(). Since leak_immutable() no longer incref the borrow count, the caller should know if the underlying value is borrowed or not. No Python world is involved. That's why we can simply use the panicking borrow_mut().

setup: don't skip the search for global hg.exe if there is no local instance The point of trying not to blindly execute `hg` on Windows is that the local hg.exe would be given precedence, and if py3 isn't on PATH, it errors out with a modal dialog. But that's not a problem if there is no local executable that could be run. The problem that I recently ran into was I upgraded the repo format to use zstd. But doing a `make clean` deletes all of the supporting libraries, causing the next run to abort with a message about not understanding the `revlog-compression-zstd` requirement. By getting rid of the local executable in the previous commit when cleaning, we avoid leaving a broken executable around, and avoid the py3 PATH problem too. There is still a small hole in that `hg.exe` needs to be deleted before switching between py2/py3/PyOxidizer builds, because the zstd module won't load. But that seems like good hygiene anyway. Differential Revision: https://phab.mercurial-scm.org/D8038

make: also delete hg.exe when cleaning This will be needed for the next patch, which has more details. It has to come before the call into setup.py because even `python setup.py clean` calls hg to generate the version file. Differential Revision: https://phab.mercurial-scm.org/D8037

merge: start using the per-side copy dicts The point of this patch is mostly to clarify `manifestmerge()`. I find it much easier to reason about now. Differential Revision: https://phab.mercurial-scm.org/D7990

copies: define a type to return from mergecopies() We'll soon return two instances of many of the dicts from `copies.mergecopies()`. That will mean that we need to return 9 different dicts, which is clearly not manageable. This patch instead encapsulates the 4 dicts we'll duplicate in a new type. For now, we still just return one instance of it (plus the separate `diverge` dict). Differential Revision: https://phab.mercurial-scm.org/D7989

merge: move initialization of copy dicts to one place Differential Revision: https://phab.mercurial-scm.org/D7988

copies: print debug information about copies per side/branch Differential Revision: https://phab.mercurial-scm.org/D7987

copies: make mergecopies() distinguish between copies on each side I find it confusing that most of the dicts returned from `mergecopies()` have entries specific to one branch of the merge, but they're still combined into dict. For example, you can't tell if `copy = {"bar": "foo"}` means that "foo" was copied to "bar" on the first branch or the second. It also feels like there are bugs lurking here because we may mistake which side the copy happened on. However, for most of the dicts, it's not possible that there is disagreement. For example, `renamedelete` keeps track of renames that happened on one side of the merge where the other side deleted the file. There can't be a disagreement there (because we record that in the `diverge` dict instead). For regular copies/renames, there can be a disagreement. Let's say file "foo" was copied to "bar" on one branch and file "baz" was copied to "bar" on the other. Beacause we only return one `copy` dict, we end up replacing the `{"bar": "foo"}` entry by `{"bar": "baz"}`. The merge code (`manifestmerge()`) will then decide that that means "both renamed from 'baz'". We should probably treat it as a conflict instead. The next few patches will make `mergecopies()` return two instances of most of the returned copies. That will lead to a bit more code (~40 lines), but I think it makes both `copies.mergecopies()` and `merge.manifestmerge()` clearer. Differential Revision: https://phab.mercurial-scm.org/D7986

pathutil: mark parent directories as audited as we go Before 0b7ce0b16d8a (pathauditor: change parts verification order to be root first, 2016-02-11), we used to validate child directories before parents. It was then important to only mark the child audited only after we had audited its parent (ancestors). I'm pretty sure we don't need to do that any more, now that we audit parents before children. Differential Revision: https://phab.mercurial-scm.org/D8002

cmdutil: change check_incompatible_arguments() *arg to single iterable This makes it clearer on the call-sites that the first argument is special. Thanks to Yuya for the suggestion. Differential Revision: https://phab.mercurial-scm.org/D8018

rust: remove an unnecessary set of parentheses My build complained about this. I guess it started after I upgraded rustc. Differential Revision: https://phab.mercurial-scm.org/D8020

profiling: flush stdout before writing profile to stderr On py3, stdout and stderr appear to be buffered and this causes my command's output to be intermixed with the profiling output. Differential Revision: https://phab.mercurial-scm.org/D8024

rust: re-format with nightly rustfmt This fixes test-check-rust-format.t. Differential Revision: https://phab.mercurial-scm.org/D8025

tests: stablize test-rename-merge1.t on Windows This goes with d7622fdec3b5. Differential Revision: https://phab.mercurial-scm.org/D8036

rust-cpython: make sure PySharedRef::borrow_mut() never panics Since it returns a Result, it shouldn't panic depending on where the borrowing fails. PySharedRef::borrow_mut() will be renamed to try_borrow_mut() by the next patch.

rust-cpython: remove useless wrappers from PyLeaked, just move by map() This series prepares for migrating to the upstreamed version of PySharedRef. I found this last batch wasn't queued while rewriting the callers. While Option<T> was historically needed, it shouldn't be required anymore. I wasn't aware that each filed can be just moved.