Mercurial 7.1rc0 (2025-07-16)

Mercurial 7.1rc0 (2025-07-16)#

⚠️ These are notes for a release candidate version. Anything and everything below is subject to change before the actual 7.1 release.

This release is the first that does not support Python 3.8.

As always, a lot of patches don’t make it to the release notes.

New Features#

  • share: add a --share-source argument to hg root

  • fastexport: make it possible to ignore .gitmodules in the source repository

Many Rust-related changes

  • rust-revset: support resolving wdir()

  • rhg: allow --repo as abbreviation for --repository

  • rhg: support basic aliases

  • rhg: support -0 flag in rhg files

  • rust-annotate: support -Tjson

  • rust-annotate: support --rev wdir()

  • rust-annotate: allow --follow

Better profiling options, Rust tracebacks and tracing framework

  • profiling: support writing profiles to a directory

  • tracing: add a way of calling the Rust tracing framework from Python

  • rust-errors: add support for a runtime-configured backtrace

  • dispatch: enable Rust traceback processing when using --tracing

Improvement to debug commands

  • debugcommands: bring over functionality from debugshell extension

  • debugindexdot: add flags for more control over graph

Other noteworthy performance work

  • rhg annotate is up to 61 times faster in certain pathological cases

  • Improved performance of the low-level Rust storage primitive

  • Removed a lot of syscalls when listing things from storage with high-level APIs

  • merge: save one status in certain cases

  • merge: improve detection of subrepos in Rust fast path

  • Improved the delta encoding algorithm by avoiding computation, using better heuristics and folding deltas

  • hgtags-fnode-cache: fast path full warm when no tag exists

Developer tooling

  • setup-dev-tools: add a first version of script that install dev tools

  • setup-dev-tools: add make target to format the working copy using fix

  • setup-dev-tools: add make target to format the current stack using fix

Default Format Change#

No default format changes this version.

New Experimental Features#

Following last version’s “update from null”, this is a Rust version of the update logic when all tracked files are clean and we are not merging. It is on by default if you have Rust enabled: if you encounter any problems use rust.update-from-clean=no to disable it, and please let us know what the problem is.

  • rust: add an “update from clean” fast-path

New flags are being added to the revlog and transmitted over the network to help with copytracing and delta encoding.

  • revlog: introduce a FLAG_FILELOG_META revlog flag and requirements

  • changegroup: use REVIDX_HASMETA in changegroup ‘04’

  • revlog: add a delta-info-flag requirements

  • changegroup: transmit snapshot level information in cg4

  • delta-search: add a option to ignore suspicious delta

A temporary store encoding that should only exist for one version of Mercurial, until we get a better solution to a very specific problem that you probably don’t have.

  • store: add a first version of a “plain” encoding

  • rust: add support for plain encoding

Bug Fixes#

  • diff: fix function name context detection (issue6965)

  • merge: filter ambiguous files and/or wait for fs tick in applyupdates

  • rust: handle censored revisions according to the config

  • changelog: also disable sparse-revlog when disabling generaldelta

  • rust-repo: unconditionally load the dirstate before loading the changelog

  • revlog: fix a bytes vs str crash when emitting a deprecation warning

  • rust-annotate: prefix abort messages with “abort:”

  • debugshell: return an exit code 1 on exception

Backwards Compatibility Changes#

  • fastexport: add support for Git subrepositories (BC)

  • pycompat: drop support for Python 3.8 (BC)

  • annotate: use exit code 255 for missing files

  • contrib: delete debugshell extension

  • rust: update minimum Rust supported version to 1.85.1 for the 7.1 cycle

Internal API Changes#

  • revlog: add “writable” parameter to revlog

  • revlog: enforce that filelog get the writable parameter passed

Miscellaneous#

As with every release for a while, there were a ton of patches helping with adding typing information to our Python code, and catching bugs while doing so. The Pytype CI job itself was upgraded to be more helpful.

We’ve migrated our Rust<->Python bridge from using the deprecated rust-cpython to the new standard PyO3.

  • rust: remove hg-cpython

  • rust: move from log to tracing-based logging

We’ve upgraded our CI to be much easier to update, more up-to-date and use smaller images

  • ci: switch the “checks” job to a “v3.0” images

Other mentions

  • debugnodemap: print a message when no action was specified

  • pyproject: SPDX license expression and license-files (PEP 639)

  • apache-server: update the setup from Wheezy to Buster

  • apache-server: update the README, add Anubis, add notes about ProxyPass

  • rust-pyo3: raise proper Exceptions in more cases