Rust .msi installer ignores current install

[abonander]

One of the convenient features of the defunct .exe installer is it would remove old library archives before installing new ones, so that one could update Rust just by running over the current install. The .msi installer does not do this, it just naively installs the new libraries next to the old ones, and Rust can't figure out which to use:

rustbook\src\main.rs:1:1: 1:1 error: multiple matching crates for `std`
rustbook\src\main.rs:1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
                       ^
note: candidates:
note: path: \\?\C:\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib\std-d855c359.dll
note: path: \\?\C:\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib\libstd-d855c359.rlib
note: crate name: std
note: path: \\?\C:\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib\std-74fa456f.dll
note: path: \\?\C:\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib\libstd-74fa456f.rlib
note: crate name: std
rustbook\src\main.rs:1:1: 1:1 error: found staticlib `std` instead of rlib or dylib
rustbook\src\main.rs:1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
                       ^
rustbook\src\main.rs:1:1: 1:1 help: please recompile this crate using --crate-type lib
rustbook\src\main.rs:1:1: 1:1 note: crate `std` path #1: C:\Rust\bin\rustlib\x86_64-pc-windows-gnu\lib\libstdc++.a
error: aborting due to 2 previous errors
Could not compile `rustbook`.

To learn more, run the command again with --verbose.

I can't simply update my Rust install anymore. I have to remove the old libraries either manually or by running the Rust uninstaller. This is a major convenience discrepancy compared to using Rust on the Unix-based platforms.

[abonander]

Note: this issue is about installing a new version of Rust over an old version in the same folder. It doesn't concern installing separate versions of Rust in separate folders. An "Update" option to the installer that automatically selects the current Rust install path would be great as well, as it currently suggests something rather arbitrary, C:\Program Files\Rust nightly update 1.3 or something like that.

[retep998]

I think because the name of the software changes with each version of Rust, the msi installation system ends up thinking that they are two different pieces of software and thus doesn't recognize the old version to ask you what you want to do with it. Ideally the installer would detect if there is an existing installation of Rust in the folder you're installing to and automatically uninstall the old one, but I'm not sure how to do that with msi.

[abonander]

It's disappointing because the .exe installer did this. It was my preferred method of updating when it was still available.

[retep998]

cc @brson @vadimcn

[vadimcn]

The .msi installer only updates versions which have the same (platform,channel,major,minor) tuple. For example it will update nightly 1.3.X -> 1.3.Y in-place. Everything else is treated as different software version - to enable installing them side-by side (which the .exe version did not allow). The detection is based on versions stored in the registry, not on the installation path.
In other words, this is by design. In order to gain something (side-by-side installs) you lose something (ease of upgrade for users who don't care about side-by-side)...

[abonander]

That's an issue because I only really bother to update when the minor version gets bumped, as I expect is the same with many people. And, like I said, this is a pretty big discrepancy when you look at how easy it is to install and update Rust on the *nixes, package manager or otherwise.

Why does the Rust installer care about side-by-side installs anyways? Can't multirust be updated to support Windows for this? Is the .exe installer still being built but just doesn't have a link provided for it?

[vadimcn]

Why does the Rust installer care about side-by-side installs anyways?

This is based partly on my own preferences and partly because Python also does upgrades this way.

Can't multirust be updated to support Windows for this?

Multirust is a shell script that uses a bunch of unix command line tools, so it won't work on Windows without msys.

[brson]

Nominating because this is surprising behavior to a lot of people.

[alexcrichton]

triage: P-medium

Would love to fix, but doesn't seem super high priority right now.