view relnotes/5.7 @ 50336:cf4d2f31660d stable

chg: populate CHGHG if not set

Normally, chg determines which `hg` executable to use by first consulting the
`$CHGHG` and `$HG` environment variables, and if neither are present defaults
to the `hg` found in the user's `$PATH`. If built with the `HGPATHREL` compiler
flag, chg will instead assume that there exists an `hg` executable in the same
directory as the `chg` binary and attempt to use that.

This can cause problems in situations where there are multiple actively-used
Mercurial installations on the same system. When a `chg` client connects to a
running command server, the server process performs some basic validation to
determine whether a new command server needs to be spawned. These checks include
things like checking certain "sensitive" environment variables and config
sections, as well as checking whether the mtime of the extensions, hg's
`__version__.py` module, and the Python interpreter have changed.

Crucially, the command server doesn't explicitly check whether the executable it
is running from matches the executable that the `chg` client would have
otherwise invoked had there been no existing command server process. Without
`HGPATHREL`, this still gets implicitly checked during the validation step,
because the only way to specify an alternate hg executable (apart from `$PATH`)
is via the `$CHGHG` and `$HG` environment variables, both of which are checked.

With `HGPATHREL`, however, the command server has no way of knowing which hg
executable the client would have run. This means that a client located at
`/version_B/bin/chg` will happily connect to a command server running
`/version_A/bin/hg` instead of `/version_B/bin/hg` as expected. A simple
solution is to have the client set `$CHGHG` itself, which then allows the
command server's environment validation to work as intended.

I have tested this manually using two locally built hg installations and it
seems to work with no ill effects. That said, I'm not sure how to write an
automated test for this since the `chg` available to the tests isn't even built
with the `HGPATHREL` compiler flag to begin with.

== 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`.