/usr/share/rustc change from directory to symlink

[Skia]

Hello Max!

Here is your bug about the upgrade path for /usr/share/rustc change from being a directory in whatever older rust-default version to being a symlink in the newest ones.
Basically we'll need to make sure that the newest packages will remove any existing directory to be able to replace it with a symlink.

For the context, I faced that situation on my Ubuntu devel (right now resolute) laptop, that is basically rolling release, so I'm not sure how normal users are affected right now.

Happy bug fixing :-)

[Max Gilmour (maxgmr)]

Hi Skia, thanks for the report!

Confirmed — the upgrade story is broken when transitioning from pre-versioned rustc (provided by the rustc source package) to versioned rustc (provided by rust-defaults).

Currently, this is only possible when upgrading from Noble to Plucky or Noble to Resolute.

==============
24.04 to 25.04
==============
root@rust-upgrade:~# lsb_release -d
No LSB modules are available.
Description: Ubuntu 24.04.3 LTS
root@rust-upgrade:~# apt update && apt upgrade -y
[...]
root@rust-upgrade:~# apt install -y rustc
[...]
root@rust-upgrade:~# ls -l /usr/share | grep rustc
drwxr-xr-x 3 root root 4096 Nov 14 16:54 rustc

root@rust-upgrade:~# sed -i 's/Prompt=lts/Prompt=normal/g' /etc/update-manager/release-upgrades
root@rust-upgrade:~# do-release-upgrade
[...]

root@rust-upgrade:~# lsb_release -d
Description: Ubuntu 25.04
root@rust-upgrade:~# ls -l /usr/share | grep rustc
drwxr-xr-x 2 root root 4096 Nov 14 16:59 rustc
drwxr-xr-x 3 root root 4096 Nov 14 16:59 rustc-1.84
root@rust-upgrade:~# ls -Ll /usr/share/rustc
total 0

==============
24.04 to devel
==============
root@rust-upgrade-lts:~# lsb_release -d
No LSB modules are available.
Description: Ubuntu 24.04.3 LTS
root@rust-upgrade-lts:~# apt update && apt upgrade -y
[...]
root@rust-upgrade-lts:~# apt install -y rustc
[...]
root@rust-upgrade-lts:~# ls -l /usr/share | grep rustc
drwxr-xr-x 3 root root 4096 Nov 14 17:07 rustc

root@rust-upgrade-lts:~# do-release-upgrade -d
[...]

root@rust-upgrade-lts:~# lsb_release -d
Description: Ubuntu Resolute Raccoon (development branch)
root@rust-upgrade-lts:~# ls -l /usr/share | grep rustc
drwxr-xr-x 2 root root 4096 Nov 14 17:14 rustc
drwxr-xr-x 3 root root 4096 Nov 14 17:14 rustc-1.88
root@rust-upgrade-lts:~# ls -Ll /usr/share/rustc
total 0

===================================================
Expected contents of /usr/share/rustc after upgrade
===================================================
root@expected:~# lsb_release -d
Description: Ubuntu Resolute Raccoon (development branch)
root@expected:~# apt update && apt upgrade -y
[...]
root@expected:~# apt install rustc -y
[...]
root@expected:~# ls -Ll /usr/share/rustc
total 8
-rw-r--r-- 1 root root 684 Aug 22 22:42 architecture.mk
drwxr-xr-x 2 root root 4096 Nov 14 17:09 bin

[Petrichor Park (petrakat)]

Hello, this is currently blocking me from continuing to package cargo-audit. I upgraded from Noble to Questing and can't get /usr/share/rustc/architecture.mk to work.

Do we have a workaround?

[Max Gilmour (maxgmr)]

> Hello, this is currently blocking me from continuing to package cargo-audit. I upgraded from > Noble to Questing and can't get /usr/share/rustc/architecture.mk to work.
>
> Do we have a workaround?

The workaround is reinstalling the package:

root@test:~# lsb_release -d
Description: Ubuntu 25.10
root@test:~# apt-cache policy rustc
rustc:
  Installed: 1.85.1ubuntu1
  Candidate: 1.85.1ubuntu1
  Version table:
 *** 1.85.1ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu questing/main amd64 Packages
        100 /var/lib/dpkg/status
root@test:~# ls -lL /usr/share/rustc
total 0
root@test:~# apt remove -y rustc && apt install rustc -y
[...]
root@test:~# ls -lL /usr/share/rustc
total 8
-rw-r--r-- 1 root root 684 Aug 19 20:50 architecture.mk
drwxr-xr-x 2 root root 4096 Dec 8 18:32 bin