Bug#1115227: libllvm19: Installing libllvm19:i386 on a AMD64 system with libllvm19 already installed will force apt to remove libllvm19 and dependent packages.

[Simon McVittie]

On Sun, 14 Sep 2025 at 17:09:17 +0200, Sebastian Ramacher wrote:
>On 2025-09-14 14:19:00 +0200, Sebastian Ramacher wrote:
>> On 2025-09-14 12:31:48 +0100, Bogdans Krutilins wrote:
>> > - Attempted to install libllvm19:i386 as it is a requirement for Steam.
>> > - I ran "sudo apt install libllvm19:i386". This caused apt to state that it
>> > will be removing libllvm19, xorg, nvidia-driver ffmpeg, clang, chromium etc.

This was caused by an overly general solution to #1100981. 
https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/commit/fb68d9241f1338333cf5260136378e4a7ef43308 
removed "Multi-Arch: same" from the packages that were not multiarch 
co-installable (such as libmlir-19, which is not co-installable because 
it contains /usr/lib/llvm-19/lib/libMLIR.so.19.1), but also removed that 
annotation from the packages that *were* multiarch co-installable, such 
as libllvm19 (which is co-installable, because it only contains 
non-colliding paths like /usr/lib/x86_64-linux-gnu/libLLVM.so.19.1).

It would be useful if maintainers of packages that are involved in the 
multiarch graphics stack, like LLVM and Mesa, could keep both the :amd64 
and :i386 flavours of a package like mesa-vulkan-drivers installed on 
their development machines (assuming they use x86, which I imagine that 
most still do) - that would avoid this sort of thing getting uploaded 
and regressing end-user systems.

Thanks,
     smcv