rust-index: using the `hg::index::Index` in ancestors iterator and lazy set
Since there is no Rust implementation for REVLOGV2/CHANGELOGv2, we declare
them to be incompatible with Rust, hence indexes in these formats will use
the implementations from Python `mercurial.ancestor`. If this is an unacceptable
performance hit for current users of these formats, we can later on add Rust
implementations based on the C index for them or implement these formats for
the Rust indexes.
Among the challenges that we had to meet, we wanted to avoid taking the GIL each
time the inner (vcsgraph) iterator has to call the parents function. This would probably
still be acceptable in terms of performance with `AncestorsIterator`, but not with
`LazyAncestors` nor for the upcoming change in `MissingAncestors`.
Hence we enclose the reference to the index in a `PySharedRef`, leading to more
rigourous checking of mutations, which does pass now that there no logically immutable
methods of `hg::index::Index` that take a mutable reference as input.
== New Features ==
* There is a new config section for templates used by hg commands. It
is called `[command-templates]`. Some existing config options have
been deprecated in favor of config options in the new
section. These are: `ui.logtemplate` to `command-templates.log`,
`ui.graphnodetemplate` to `command-templates.graphnode`,
`ui.mergemarkertemplate` to `command-templates.mergemarker`,
`ui.pre-merge-tool-output-template` to
`command-templates.pre-merge-tool-output`.
* There is a new set of config options for the template used for the
one-line commit summary displayed by various commands, such as `hg
rebase`. The main one is `command-templates.oneline-summary`. That
can be overridden per command with
`command-templates.oneline-summary.<command>`, where `<command>`
can be e.g. `rebase`. As part of this effort, the default format
from `hg rebase` was reorganized a bit.
* `hg purge` is now a core command using `--confirm` by default.
* `hg diff` and `hg extdiff` now support `--from <rev>` and `--to <rev>`
arguments as clearer alternatives to `-r <revs>`. `-r <revs>` has been
deprecated.
* The memory footprint per changeset during pull/unbundle
operations has been further reduced.
* There is a new internal merge tool called `internal:mergediff` (can
be set as the value for the `merge` config in the `[ui]`
section). It resolves merges the same was as `internal:merge` and
`internal:merge3`, but it shows conflicts differently. Instead of
showing 2 or 3 snapshots of the conflicting pieces of code, it
shows one snapshot and a diff. This may be useful when at least one
side of the conflict is similar to the base. The new marker style
is also supported by "premerge" as
`merge-tools.<tool>.premerge=keep-mergediff`.
* External hooks are now called with `HGPLAIN=1` preset. This has the side
effect of ignoring aliases, templates, revsetaliases, and a few other config
options in any `hg` command spawned by the hook. The previous behavior
can be restored by setting HGPLAINEXCEPT appropriately in the parent process.
See `hg help environment` for the list of items, and how to set it.
* The `branchmap` cache is updated more intelligently and can be
significantly faster for repositories with many branches and changesets.
* The `rev-branch-cache` is now updated incrementally whenever changesets
are added.
== New Experimental Features ==
* `experimental.single-head-per-branch:public-changes-only` can be used
restrict the single head check to public revision. This is useful for
overlay repository that have both a publishing and non-publishing view
of the same storage.
== Bug Fixes ==
== Backwards Compatibility Changes ==
* `--force-lock` and `--force-wlock` options on `hg debuglock` command are
renamed to `--force-free-lock` and `--force-free-wlock` respectively.
== Internal API Changes ==
* `changelog.branchinfo` is deprecated and will be removed after 5.8.
It is superseded by `changelogrevision.branchinfo`.