rustup self update doesn't update DisplayVersion

[ave9858]

Problem

When updating rustup from a prior release using rustup update, the DisplayVersion in the registry isn't updated from the old release version. This will result in tools like winget thinking rustup is outdated, and might confuse users.

Steps

1. Install an older release of rustup that sets DisplayVersion such as 1.26.0
2. Run rustup update, and check that rustup is updated to the latest version
3. Open the "Uninstall a program" menu in control panel or check HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Rustup in the registry to see the outdated version number

Possible Solution(s)

Maybe do_add_to_programs isn't called for updates? I haven't checked the code yet.

Notes

Related to #3047 and #3055

Rustup version

rustup 1.27.0 (bbb9276d2 2024-03-08)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.77.0 (aedd173a2 2024-03-17)`

Installed toolchains

Default host: x86_64-pc-windows-msvc
rustup home:  C:\Users\User\.rustup

stable-x86_64-pc-windows-msvc (default)
rustc 1.77.0 (aedd173a2 2024-03-17)

[rami3l]

@ave9858 Thanks for filing this issue!

Unfortunately I don't currently use Windows and I wonder how exactly winget expect DisplayVersion to change, and I'm curious about how we would be able to verify the fix if it's ever made. @jedieaston maybe you as the original author of #3047 can provide more context on this one?

https://github.com/rust-lang/rustup/pull/3047/files only handles the addition of DisplayVersion on installation. I think running do_add_to_programs() during a self update may be overwhelming though, and a better thing to do would be extracting the addition into a function and use it in both rustup-init and rustup self update.

[djc]

Also cc @ChrisDenton as our resident Windows expert?

[ChrisDenton]

Looking at

rustup/src/cli/self_update/windows.rs

Line 503 in 0c501d5

pub(crate) fn do_add_to_programs() -> Result<()> {

@rami3l's plan looks good to me. It seems like updating the DisplayVersion would be enough but I guess the only tricky thing would be to make sure it doesn't overwrite another installation of rustup. Not that rustup particularly supports having two concurrent installs.