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This is why I wish more package managers had a (more) formalized versions of what Gentoo calls "slots". One of the major uses of slots in Gentoo is to represent

This is why I wish more package managers had a (more) formalized versions of what Gentoo calls "slots". One of the major uses of slots in Gentoo is to represent major versions of libraries, s.t. LLVM 3.5 would be in the "3.5" slot, and LLVM 4 would be in the "4" slot. Dependencies are declared against slots, and the standard *nix naming convention for shared objects trivially lets multiple slots be installed at the same time. (Other package managers tend to emulate slots by simply having multiple packages with the slot number embedded in the package name itself. Debian/Ubuntu, for example, does this, and it isn't clear to me why their scheme would preclude having multiple LLVMs installed. That said, Gentoo always seems to have difficultly with clang/llvm, so my gut wonders if there is something more at play here.)

int_19h 10y ago
Debian does exactly that - the unstable repo currently has: llvm-3.4 llvm-3.5 llvm-3.6 llvm-3.7 llvm-3.8 llvm-3.9 llvm-4.0 Note that these are all package names. Each is then versioned separately - e.g. 4.0 is currently at v4.0-1, and 3.8 is at 3.8.1-18.
slrz 10y ago
It's not a technical problem. All distro package managers allow for parallel-installed libraries one way or another. What's necessary for your distro to actually ship multiple versions is someone stepping up to actually maintain the thing, dealing with bug reports and monitoring security issues. For libraries with many users that happens all the time. See the parallel packages for OpenSSL 1.0 and 1.1 in most distro repositories. For less popular libraries it's often easier to just patch all users and only ship the most recent version. Nowadays LLVM seems firmly placed in the first camp, as patching programs to work with different LLVM versions can be a lot of work and there are quite a lot of them. Looking into the Debian repos, you find packages for LLVM 3.7, 3.8, 3.9 and 4.0, in addition there's even a 5.0 pre-release snapshot. It's similar with Fedora and probably other distributions.

int_19h 10y ago

Debian does exactly that - the unstable repo currently has: llvm-3.4 llvm-3.5 llvm-3.6 llvm-3.7 llvm-3.8 llvm-3.9 llvm-4.0 Note that these are all package names. Each is then versioned separately - e.g. 4.0 is currently at v4.0-1, and 3.8 is at 3.8.1-18.

slrz 10y ago

It's not a technical problem. All distro package managers allow for parallel-installed libraries one way or another. What's necessary for your distro to actually ship multiple versions is someone stepping up to actually maintain the thing, dealing with bug reports and monitoring security issues. For libraries with many users that happens all the time. See the parallel packages for OpenSSL 1.0 and 1.1 in most distro repositories. For less popular libraries it's often easier to just patch all users and only ship the most recent version. Nowadays LLVM seems firmly placed in the first camp, as patching programs to work with different LLVM versions can be a lot of work and there are quite a lot of them. Looking into the Debian repos, you find packages for LLVM 3.7, 3.8, 3.9 and 4.0, in addition there's even a 5.0 pre-release snapshot. It's similar with Fedora and probably other distributions.