rhg: Return an error code for `rhg config Section.idontexist` This is what Python-based hg does. Differential Revision: https://phab.mercurial-scm.org/D10145

rhg: Fall back to Python for --version Clap has some built-in support for printing something on --version, but it looks different than what Pytho-based hg does. Also, at the moment we’re not giving version numbers to rhg separate from the Mercurial version. Differential Revision: https://phab.mercurial-scm.org/D10144

rhg: Exit with an error code if `files` finds nothing This matches the behavior of Python-based hg. Differential Revision: https://phab.mercurial-scm.org/D10143

rhg: `cat` command: print error messages for missing files And exit with an error code if no file was matched. This matches the behavior of Python-based hg. Differential Revision: https://phab.mercurial-scm.org/D10142

rhg: Silently ignore missing files in config %include … instead of aborting with an error message. This is what Python-based hg does. Differential Revision: https://phab.mercurial-scm.org/D10141

rhg: Add support for environment variables in config include paths Some tests rely on this. Differential Revision: https://phab.mercurial-scm.org/D10140

rhg: Add support for the HGRCSKIPREPO environment variable It’s easy enough and affects tests, well, that test that feature. Differential Revision: https://phab.mercurial-scm.org/D10139

rhg: Don’t make repository path absolute too early Some error messages want to include a relative path, which affects the output of some tests. Differential Revision: https://phab.mercurial-scm.org/D10138

rhg: Fall back to Python if ui.relative-paths is configured This feature is not supported yet, and affects the output of some tests. Differential Revision: https://phab.mercurial-scm.org/D10137

tests: clarify some missing output in test-merge-subrepos This makes the test behavior clearer, especially, why the output are inconsistent. Differential Revision: https://phab.mercurial-scm.org/D10136

tests: Adapt expected output for minor differences with rhg Differential Revision: https://phab.mercurial-scm.org/D10135

rhg: Add support for --cwd This affect the meaning of relative paths in `--repository`, which are resolved "early" by rhg in order to load config which is needed before fallback to Python is considered. An incorrect path could cause errors when loading a non-existent repo, leading to failing tests even when fallback is enabled. Differential Revision: https://phab.mercurial-scm.org/D10134

rhg: Align with Python on some more error messages Differences can cause some tests to fail Differential Revision: https://phab.mercurial-scm.org/D10133

rhg: Add an allow-list of ignored extensions Because rhg doesn’t know how a Python extension would affect behavior it implements in Rust, when an unsupported extension is enabled it conservatively falls back to Python-based hg. However many users will have unsupported extensions enabled in practice. Maybe they don’t actually affect rhg behavior, but we don’t know. This adds a `rhg.ignored-extensions` configuration that lets users list extensions that rhg can safely ignore and proceed even if they’re not supported in Rust. Differential Revision: https://phab.mercurial-scm.org/D10188

rhg: Fall back to Python if unsupported extensions are enabled Extensions might affect behavior in ways we can’t anticipate, so just ignoring them is not correct. Later we’ll add opt-in configuration to ignore specific extensions. Differential Revision: https://phab.mercurial-scm.org/D10112

rhg: Sort config files when adding a directory For example in `/etc/mercurial/hgrc.d/` or with `HGRCPATH=some-directory`. Previously files where parsed in the order returned by the filesystem, which is undefined. But order is significant when multiple files define the same configuration key: the "last" one wins. Differential Revision: https://phab.mercurial-scm.org/D10111

rhg: Align config file parse error formatting with Python Differences can cause tests to fail Differential Revision: https://phab.mercurial-scm.org/D10110

rhg: Fall back to Python for bundle repositories rhg does not support bundles at all, yet. Differential Revision: https://phab.mercurial-scm.org/D10102

rhg: Fall back to Python on --repository with an URL A low-hanging fruit to improve on this would be to properly parse and handle `file:` URLs. But other Python-based hg supports some other URL schemes for features that rhg does not support yet. Differential Revision: https://phab.mercurial-scm.org/D10101

rhg: Print non-absolutized path in "repository {} not found" errors … like Python does. Differences in ouput can cause tests to fail. Differential Revision: https://phab.mercurial-scm.org/D10100

rhg: Align "malformed --config" error message with Python Differences in error message formatting can cause tests to fail. Differential Revision: https://phab.mercurial-scm.org/D10099

rhg: Fall back to Python on unsupported `rhg config <section>` Printing an entire section (as opposed to a single value with `rhg config foo.bar`) is not supported yet in Rust only. Differential Revision: https://phab.mercurial-scm.org/D10098

rhg: Fall back to Python for unsupported revset syntax rhg only supports a small subset of the syntax. On parse error, this gives Python a chance instead of aborting immediately. Differential Revision: https://phab.mercurial-scm.org/D10097

tests: Add `rhg` and `no-rhg` for #require and #if in .t files With this we can allow some small differences in expected output between Rust-based and Python-based code paths. Differential Revision: https://phab.mercurial-scm.org/D10096

tests: Enable rhg fallback to Python by default in tests This premise of `run-tests.py --rhg`: fallback should make `rhg` behave the same as `hg`, except faster in some cases. To test run the whole test suite with installed `rhg` as `hg` and with fallback enabled. Differential Revision: https://phab.mercurial-scm.org/D10187

rhg: Add environment variables for fallback configuration For the `rust-tests.py --rhg` we want every `hg` command in tests to run `rhg` with fallback enabled, but other methods of setting configuration are limited or disruptive as discussed in code comment. Differential Revision: https://phab.mercurial-scm.org/D10186

paths: add a `*` special path to define default sub option Differential Revision: https://phab.mercurial-scm.org/D10163

ui: pass a `ui` object to `paths.getpath` I want to introduce more path's suboption and make it possible to use default value for them. Processing theses sub-options might result in warnings. We need a `ui` object to issue such warnings. To make things simpler, we add an helper method on the `ui` object. Differential Revision: https://phab.mercurial-scm.org/D10162

configitems: add TODOs blocking the move out of experimental for revlogv2 These are the todos so far, we probably will have more, but we might as well list them while they're fresh in our minds. Differential Revision: https://phab.mercurial-scm.org/D10216

sidedata-exchange: rewrite sidedata on-the-fly whenever possible When a A exchanges with B, the difference of their supported sidedata categories is made, and the responsibility is always with the client to generated it: - If A pushes to B and B requires category `foo` that A does not have, A will need to generate it when sending it to B. - If A pulls from B and A needs category `foo`, it will generate `foo` before the end of the transaction. - Any category that is not required is removed. If peers are not compatible, abort. It is forbidden to rewrite sidedata for a rev that already has sidedata, since that would introduce unreachable (garbage) data in the data file, something we're not prepared for yet. Differential Revision: https://phab.mercurial-scm.org/D10032