Git 3.0, Rust and other timelines

[rimrul]

Git 3.0 will most likely require Rust. This comes with a couple of minor challenges for Git for Windows. While there is no fixed release date for Git 3.0 yet, I'd like to discuss how we want to approach these, so we are prepared for Git 3.0.

ARM64

I don't see any challenges for ARM64, we could probably start building WITH_RUST right now.

Windows 8.1 support

We're currently still supporting Windows 8.1. Rust raised the requirements for the regular *-windows-gnu targets to Windows 10 in version 1.76.

Theoretically we could stick to an older (unmaintained) version. Git currently only requires 1.49 or newer. We'd probably have to build our own mingw-w64-rust package (based on Msys2s old PKGBUILD).

We could also switch to the new tier 3 *-win7-windows-gnu targets available since version 1.86. Being tier 3 targets, rust doesn't guarrantee that these even build. We'd also have to build our own mingw-w64-rust package (based on MSYS2s current PKGBUILD).

We could also drop support for Windows 8.1, but I'm not sure how intertwined our 32-bit MinGit timeline until 2029, VS2019s EOL in 2029 and Git Credential Managers Windows 8.1 Support until 2029 are.

32-bit support

There are efforts in MSYS2 to drop the 32-bit *-windows-gnu targets. Our options in that case are pinning an old (i.e. before the dropping) rust version or building our own mingw-w64-rust package.

@dscho @mjcheetham , what are your thoughts?

[rimrul]

GCM are adjusting their Windows 8.1 timeline

This is planned to be the last release major release that supports Windows 7 and 8.x. We will be moving off of .NET Framework to .NET (Core) on Windows this year.

[mjcheetham]

Correct. Our plan for Windows 8.1 - for VS2019's sake and usage - is to provide a special release branch, release/v2.7 (exact name undecided) and make only security releases until 2029.

[mjcheetham]

Given Git for Windows is providing a specific MinGit i686 package, fixed to an older MSYS2 runtime, for VS to consume, could we not also apply the same plan for Windows 8.1 support, in that only 32-bit MinGit will support Windows 8.1, and will forever be a Git 2.x release? Git 3.x requiring Rust and Win10+ (and 64-bit Intel/ARM).

[rimrul]

We could. That would mean a mingw-w64-git2 package and minGit only releases, but it could be done.

[dscho]

I could also imagine simply dropping full Windows 8.1 support (and only continue to support it via i686 MinGit v2.x, a "forever release").

We have to be mindful of the remaining human resources to maintain this complex software, and I don't think that we can afford to maintain a proper LTS release, certainly not when the Git maintainer himself is totally unwilling to maintain an LTS version or even let anyone maintain such an LTS version within the Git project itself (even though the complexity of the Git project is substantially lower than Git for Windows, given that it releases only source code tags, not even having to worry about any dependencies). The absence of such an upstream commitment makes it even less tenable for this downstream project.

[dscho]

I think I'm pretty settled on this plan: With Git 3.0, Git for Windows will only support Windows 10, via x64 and arm64 variants. There will be a last MinGit v2.x release train that will be maintained as best as we can until 2029.

This also allows us to switch to UCRT builds even for x64, which we'll need to do sooner or later anyway because MSYS2 deprecated MINGW64.