config: add experimental argument to the config registrar Until now, there are almost 28 config items which are considered as `experimental` but, not present in the `experimental` section of the registrar. This patch adds an `experimental` argument to the config registrar to mark such config items. Differential Revision: https://phab.mercurial-scm.org/D6728 Differential Revision: https://phab.mercurial-scm.org/D6746

tests: split joint repo/changelog fake into one for each type I'm just not comfortable with fakes that get overloaded for multiple types: too often it gets out of hand and becomes difficult to trace. Differential Revision: https://phab.mercurial-scm.org/D6725

fix: pass line ranges as value instead of callback The callback no longer takes any arguments from the inner function, so we might as well call it sooner and pass the value instead. Note the value still needs to be recomputed every iteration to account for the previous iteration's changes to the file content. Differential Revision: https://phab.mercurial-scm.org/D6727

fix: correctly parse the :metadata subconfig It's being handled as a string instead of a bool, though the thruthiness of the string makes the feature still essentially work. Added a regression test. Differential Revision: https://phab.mercurial-scm.org/D6726

fix: allow tools to use :linerange, but also run if a file is unchanged The definition of "unchanged" here is subtle, because pure deletion diff hunks are ignored. That means this is different from using the --whole flag. This change allows you to configure, for example, a code formatter that: 1. Formats specific line ranges if specified via flags 2. Does not format the entire file when there are no line ranges provided 3. Performs some other kind of formatting regardless of provided line ranges This sounds a little far fetched, but it is meant to address a specific corner case encountered in Google's use of the fix extension. The default behavior is kept because it exists to prevent mistakes that could erase uncommitted changes. Differential Revision: https://phab.mercurial-scm.org/D6723

rust-dirstate: call rust dirstatemap from Python Since Rust-backed Python classes cannot be used as baseclasses (for rust-cpython anyway), we use composition rather than inheritance. This also allows us to keep the IO operations in the Python side, removing (for now) the need to rewrite VFS in Rust, which would be a heavy undertaking. Differential Revision: https://phab.mercurial-scm.org/D6634

rust-dirstate: rust-cpython bridge for dirstatemap This change also showcases the limitations of the `py_shared_ref!` macro. See the previous commit 'rust-dirstate: rust implementation of dirstatemap` for an explanation for the TODOs in the code. Differential Revision: https://phab.mercurial-scm.org/D6633

rust-dirstate: rust implementation of dirstatemap The `dirstatemap` is one of the last building blocks needed to get to a `dirstate.walk` Rust implementation. Disclaimer: This change is part of a big (10) series of patches, all of which started as one big changeset that took a long time to write. This `dirstatemap` implementation is a compromise in terms of complexity both for me and for the reviewers. I chose to submit this patch right now because while it is not perfect, it works and is simple enough (IMHO) to be reviewed. The Python implementation uses a lot of lazy propertycaches, breaks encapsulation and is used as an iterator in a lot of places, all of which dictated the somewhat unidiomatic patterns in this change. Like written in the comments, rewriting this struct to use the typestate pattern might be a good idea, but this is a good first step. Differential Revision: https://phab.mercurial-scm.org/D6632

rust-cpython: add macro for sharing references Following an experiment done by Georges Racinet, we now have a working way of sharing references between Python and Rust. This is needed in many points of the codebase, for example every time we need to expose an iterator to a Rust-backed Python class. In a few words, references are (unsafely) marked as `'static` and coupled with manual reference counting; we are doing manual borrow-checking. This changes introduces two declarative macro to help reduce boilerplate. While it is better than not using macros, they are not perfect. They need to: - Integrate with the garbage collector for container types (not needed as of yet), as stated in the docstring - Allow for leaking multiple attributes at the same time - Inject the `py_shared_state` data attribute in `py_class`-generated structs - Automatically namespace the functions and attributes they generate For at least the last two points, we will need to write a procedural macro instead of a declarative one. While this reference-sharing mechanism is being ironed out I thought it best not to implement it yet. Lastly, and implementation detail renders our Rust-backed Python iterators too strict to be proper drop-in replacements, as will be illustrated in a future patch: if the data structure referenced by a non-depleted iterator is mutated, an `AlreadyBorrowed` exception is raised, whereas Python would allow it, only to raise a `RuntimeError` if `next` is called on said iterator. This will have to be addressed at some point. Differential Revision: https://phab.mercurial-scm.org/D6631

rust-docstrings: add missing module docstrings Differential Revision: https://phab.mercurial-scm.org/D6630