run-tests: alias hg to hg.exe on Windows To enable legacy stdio mode on Windows, hg.exe needs to be updated. But before that, we actually have to use it when running the tests. I *think* what was happening before was when MSYS invoked `hg`, it looked at the shbang line and ran python.exe found there. The test harness must be updating $PATH to include the python used to launch it, and therefore it ran py3. As a side note, this also fixed `py -3 run-tests.py` (without --local), which complained about the space in the shbang line before this. This should also help in WSL, because the explicit '.exe' is needed to invoke a Windows app instead of invoking the Linux app. I have no idea why this change capitalizes Lib in the tests, as it was previously lowercase for both py2 and py3.

py3: conditionalize the python version in test-install.t

tests: followup on network related errors on Debian 9 First, update test-clonebundles.t which was failing since the introduction of the `$EADDRNOTAVAIL$` common pattern. Also update two tests from 8695fbe17f7c with a more compact condition line. Differential Revision: https://phab.mercurial-scm.org/D5445

py3: unimplement RevlogError.__str__() On Python 2, str(exc) would crash if __str__() returned a unicode containing non-ASCII characters.

py3: use forcebytestr() to stringify hook exception This fixes test-narrow-exchange.t.

color: fix a documentation typo

py3: quote $PYTHON in test-patchbomb.t for Windows I couldn't get the quoting right in the environment variable, so now it's a function.

rust-cpython: testing the bindings from Python This is easier and more convincing than doing the same tests from a Rust tests module. Differential Revision: https://phab.mercurial-scm.org/D5437

rust-cpython: build via HGWITHRUSTEXT=cpython The existing behaviour, building the direct ffi bindings if HGIWTHRUSTEXT is just set is unchanged, but if HGWITHRUSTEXT is cpython, then the cpython bindings (aka mercurial/rustext.so) are built. Differential Revision: https://phab.mercurial-scm.org/D5436

rust: better treatment of cargo/rustc errors Differential Revision: https://phab.mercurial-scm.org/D5435

rust-cpython: start cpython crate bindings This changeset introduces the hg-cpython crate, that compiles as a shared library holding a whole Python package (mercurial.rustext), with only the empty 'ancestor' submodule for now. Such bindings will be easier and safer to develop and maintain that those of `hg-direct-ffi`. They don't involve C code, only unsafe Rust that's mostly isolated within the cpython crate. The long-term goal would be to import the provided modules, such as rustext.ancestor with mercurial.policy.importmod, same as we already do with cext modules. Differential Revision: https://phab.mercurial-scm.org/D5434

rust-cpython: exclude hgcli from workspace hgcli uses a specific rust-cpython commit by indygreg, of which a PR has been derived which is not merged nor released yet. But we can't use several versions of the sys-python2.7 crate in a single workspace: it makes for a build error. Since hgcli does not at the time being need anything from hg-core, whereas the upcoming hg-cpython will. So for now we're moving hgcli aside, hoping we could base all of them on the same version of rust-cpython again in the future. Differential Revision: https://phab.mercurial-scm.org/D5433

sparse-revlog: protect C code against delta chain including nullrev For unclear reasons, some repositories include nullrev (-1). Re-computing delta for such repo remove nullrev from all chain, so some older versions have been creating them. This currently raise an IndexError with the new C code doing chain slicing as it expect all item to be positive. Both python and C code for reading delta chain preserve nullrev, and the Python code for chain slicing handle the case fine. So we take the safe route and make the new C code works fine in that case.

sparse-revlog: handle nullrev in index_get_length The more generic index_get method handle nullrev fine, we apply the same logic here.

sparse-revlog: handle nullrev in index_get_start The more generic index_get method handle nullrev fine, we apply the same logic here.

revlog: introduce a constant for nullrev in `revlog.c` The value is important enough to be explicitly tracked.

rust: translation of missingancestors This is as direct as possible a translation of the ancestor.missingancestors Python class in pure Rust. The goal for this changeset is to make it easy to compare with the Python version. We also add to Python tests the cases that helped us develop and debug this implementation. Some possible optimizations are marked along the way as TODO comments Differential Revision: https://phab.mercurial-scm.org/D5416

contrib: provide a small script that draw performance plot We have been using this script to look into the result of various runs of the `hg perfrevlogwrite` command. It seems useful enough to be shared more widely.

delta: filter nullrev out first When picking a potential candidate, we filter them on various criteria. The "different from nullrev" criteria is very fast to compute and we should process it first.

perf: report more of the higher range in perfrevlogwrite Since the delta chain length is limited to 1000 revisions, we get a new snapshot about every 1000 revisions. If we assume that the snapshot will be most of the slowest revision, the current display (99% and max) are not very precise in their area. We now include more information about this space in the default report.

help: present boolean arguments as "--[no-]foo" This should make it much more discoverable (we document it in `hg help flags`, but most users don't think to look there). Note that flags that default to None (and not False) will not get this new presentation. We can change the defaults to False later for flags where it makes sense (probably almost all boolean flags). Differential Revision: https://phab.mercurial-scm.org/D5432

help: show "default: off" for boolean flags that default to off Differential Revision: https://phab.mercurial-scm.org/D5431

help: use "default: on" instead of "default: True" "True" feels like a Python thing and not something that users should see. Differential Revision: https://phab.mercurial-scm.org/D5430

check-commit: disallow capitalization only right after topic It should be okay to write "topic: change 'default: True' to 'default: on'". Differential Revision: https://phab.mercurial-scm.org/D5429

absorb: don't prompt to apply changes when there are none to apply Differential Revision: https://phab.mercurial-scm.org/D5428

py3: add a b'' prefix in tests/test-remotefilelog-pull-noshallow.t This makes the test pass on Python 3. # skip-blame because just b'' prefix. Differential Revision: https://phab.mercurial-scm.org/D5427

error: implement __str__ on RevlogError to fix some output defects on Py3 We open-code encoding.unimethod here to avoid cycles, and do a local import of encoding when someone str()s a RevlogError. It's not my favorite solution, but it gets the job done. Differential Revision: https://phab.mercurial-scm.org/D5426

perf: add two more missing b prefixes for Python 3 # skip-blame just two more b prefixes Differential Revision: https://phab.mercurial-scm.org/D5425

match: fix doctest to use bytes instead of str Fixes doctests on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5423

py3: use pycompat.bytechr() instead of chr() in test-fastannotate-revmap.py This makes the test pass on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5422

py3: add a missing b'' prefix in contrib/perf.py # skip-blame because just b'' prefixes This fixes test-contrib-perf.t on Python 3 which started failing. Differential Revision: https://phab.mercurial-scm.org/D5421

py3: use '%d' for integers instead of '%s' This should fix test-rebase-inmemory.t which started failing on Python 3 after recent changes. Differential Revision: https://phab.mercurial-scm.org/D5420

py3: whitelist another passing test caught by buildbot Differential Revision: https://phab.mercurial-scm.org/D5419

py3: fix bad escapes of sub() replacement pattern in test-template-basic.t Python 3.7 starts complaining about it. We have to double the backslash or '\x5c' to get around.

perfdiscovery: benching findcommonheads() This works between the local repo and any peer given by its path, and should be useful for further work on discovery Differential Revision: https://phab.mercurial-scm.org/D5418

merge with stable

templatefuncs: specialize "no match" value of search() to allow % operation If Python had Maybe or Option, the type of the search() result would be Option<Mapping>, which can be considered as a 0/1 container of a Mapping. So it makes sense that {search(r'no match pattern', x) % "whatever"} is mapped to an empty string.

templatefuncs: add regexp search() function that extracts substring This can be used to extract an issue number from a commit message, for example: {search(r'\(issue([0-9]*)\)', desc) % '{1}'}

rust: changed Graph.parents to return [Revision; 2] This will allow for simple iteration on parent revisions, such as: for parent in graph.parents(rev)?.iter().cloned() This seems to be a zero overhead abstraction once built in release mode. Differential Revision: https://phab.mercurial-scm.org/D5415

rust: improved docstring In the previous wording, rustfmt wanted to cut at the == which is not very readable in my taste. Differential Revision: https://phab.mercurial-scm.org/D5414

revset: move subscript relation functions to its own dict This will help adding more relation functions in extensions. We skip short names (that consist of one letter) while raising UnknownIdentifier because such names cannot be suggested anyway: the similarity cutoff in dispatch._getsimilar() is currently 0.6.

py3: teach run-tests.py to handle exe with spaces when --local isn't specified This was the reason that no amount of quoting worked in test-hghave.t. `os.popen()` needed to be swapped out because while the added quoting around line 3124 worked on py3, it failed on py2. See 38d51371792b. The problem with `os.system()` was wrongly splitting the command on the space in 'Program Files', regardless of quoting. It looks like there are a few other instances of `os.system()` in core code, so presumably those should be replaced?

rust: adapted hg-core tests for iteration over Result Now AncestorsIterator iters on Result<Revision, GraphError>

win32: close the handles associated with a spawned child process Probably not a big deal because at this point, the call is only used when spawning a daemonized server. In that case, the parent process goes away first, so it won't prevent the child from being cleaned up.

rust: remove comment about error handling of AncestorsIterator To be align with 443eb4bc41af "rust: propagate error of index_get_parents() properly." Spotted by Georges Racinet.

perf: add perfprogress command I've noticed that progress bars can add significant overhead to tight loops. Let's add a perf command that attempts to isolate that overhead. With a default hgrc, iteration over 1M items appears to take ~3.75s on my machine. Profiling reveals ~28% of time is spent in ui.configbool() resolving the value of the progress.debug config option. Even if I set progress.disable=true, execution still takes ~2.60s, with ~59% of the time spent in ui.configbool(). Differential Revision: https://phab.mercurial-scm.org/D5407

wireprotov2: unify file revision collection and linknode derivation The old mechanism for choosing which file revisions to send in the haveparents=True case was buggy in multiple ways - the most severe of which being that file revisions were excluded when they shouldn't have been. This commit unifies the logic for deriving the filenodes that will be sent by the "filesdata" command. We now consistently read files data from manifests. The "haveparents" argument now controls whether we iterate ctx.files() or use the full manifest to derive relevant files. The logic here is still woefully lacking to fully support shallow clones. It will require an API break to fully address. This commit should at least make the server APIs emit proper data, which is strictly better than before. Differential Revision: https://phab.mercurial-scm.org/D5406

wireprotov2: send linknodes to emitfilerevisions() Previously, linknodes were calculated within emitfilerevisions() by using filectx.introrev(), which would always use the linkrev/linknode as recorded by storage. This is wrong for cases where the receiver doesn't have the changeset the linknode refers to. This commit changes the logic for linknode emission so the mapping of filenode to linknode is computed by the caller and passed into emitfilerevisions(). As part of the change, linknodes for "filesdata" in the haveparents=False case are now correct: the existing code performed a manifest walk and it was trivial to plug in the correct linknode. However, behavior for the haveparents=True case is still wrong because it relies on filtering linkrevs against the outgoing set in order to determine what to send. This will be fixed in a subsequent commit. The change test test-wireproto-exchangev2-shallow.t is a bit wonky. The test repo has 6 revisions. The changed test is performing a shallow clone with depth=1. So, only file data for revision 5 is present locally. So, the new behavior of associating the linknode with revision 5 for every file revision seems correct. Of course, when backfilling old revisions, we'll want to update the linknode. But this problem requires wire protocol support and we'll cross that bridge later. Differential Revision: https://phab.mercurial-scm.org/D5405