Over the last couple of years the appetite for bringin Rust into the
codebase has grown significantly across the developer base. Introducing
Rust is a major change though and has ramifications for the whole
ecosystem:
- Some platforms haven't yet been able to implement a Rust toolchain,
even though it is possible in theory.
- Some platforms don't have any support for Rust at all.
- Some platforms may have to figure out how to fit Rust into their
bootstrapping sequence.
Due to this, and given that Git is a critical piece of infrastructure
for the whole industry, we cannot just introduce such a heavyweight
dependency without doing our due diligence.
Instead, preceding commits have introduced a test balloon into our build
infrastructure that convert one tiny subsystem to use Rust. For now,
using Rust to build that subsystem is entirely optional -- if no Rust
support is available, we continue to use the C implementation. This test
balloon has the intention to give distributions time and let them ease
into our adoption of Rust.
Having multiple implementations of the same subsystem is not sustainable
though, and the plan is to eventually be able to use Rust freely all
across our codebase. As such, there is the intent to make Rust become a
mandatory part of our build process.
Add an announcement to our breaking changes that Rust will become
mandatory in Git 3.0. A (very careful and non-binding) estimate might be
that this major release might be released in the second half of next
year, which should give distributors enough time to prepare for the
change.
Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
Documentation/BreakingChanges.adoc | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/Documentation/BreakingChanges.adoc b/Documentation/BreakingChanges.adoc
index f8d2eba061..b72c4dd4a0 100644
--- a/Documentation/BreakingChanges.adoc
+++ b/Documentation/BreakingChanges.adoc
@@ -165,6 +165,26 @@ A prerequisite for this change is that the ecosystem is ready to support the
"reftable" format. Most importantly, alternative implementations of Git like
JGit, libgit2 and Gitoxide need to support it.
+* Git will require Rust as a mandatory part of the build process. While Git
+ already started to adopt Rust in the Git 2.52, all parts written in Rust are
+ optional for the time being. This includes:
++
+ ** Subsystems that have an alternative implementation in Rust to test
+ interoperability between our C and Rust codebase.
+ ** Newly written features that are not mission critical for a fully functional
+ Git client.
++
+Meson auto-detects the availability of a Rust toolchain and, if available,
+builds the optional Rust code. This can be changed by executing `meson configure
+-Drust=(enabled|disabled|auto)`.
++
+These changes are meant as test balloons to allow distributors of Git to prepare
+for Rust becoming a mandatory part of the build process. Once Git 3.0 is out,
+Rust becomes mandatory and it will not be possible anymore to build Git without
+it. The Git project will declare the last version before Git 3.0 to be a
+long-term support release that is maintained until alternate Rust backends like
+gcc-rs are able to build Git.
+
=== Removals
* Support for grafting commits has long been superseded by git-replace(1).
--
2.51.0.417.g1ba7204a04.dirty
