< Project:LLVM
Project:LLVM/LLVM slotting
Starting with 4.0.0, the LLVM packages are once more slotted. This means it is now possible to have multiple versions of LLVM/clang installed simultaneously.
Why slot?
Slotting serves three goals:
- Making it possible to upgrade split clang package without intermediate breakage. In particular, when upgrading from clang-X to clang-Y, the package manager must not uninstall llvm-X before clang-Y is installed.
- Making it possible to use multiple versions of clang simultaneously, e.g. to test your programs against multiple versions of the compiler.
- Making it possible to at least partially upgrade to a newer version of LLVM before all software supports it. Previously, a single package not supporting a newer LLVM version prevented the system from upgrading to a newer one.
Which packages are slotted?
There are degrees of slotting applied to various LLVM packages:
- packages that are not slotted -- only one version can be installed,
- packages that are slotted by major version -- one release of every major version can be installed (i.e. LLVM x),
- packages that are slotted by full version -- one revision of every full version can be installed (i.e. LLVM x.y.z).
The use of slotting is summarized in the table following.
| Package | Slotting | Dep type | Required LLVM version | Notes |
|---|---|---|---|---|
| Toolchain packages | ||||
| sys-devel/llvm | by major | - | - | |
| sys-devel/clang | by major | revdep of LLVM | exact match | |
| dev-util/lldb | no | revdep of LLVM+clang | exact match | |
| sys-devel/lld | no | revdep of LLVM | exact match | |
| Auxiliary packages | ||||
| dev-ml/llvm-ocaml | no | revdep of LLVM | exact match | |
| dev-python/clang-python | no | revdep of clang | any? | dlopen()s clang libraries without SONAME, probably dangerous |
| dev-python/lit | no | dep of most pkgs | exact match | required for tests only, can cause conflict when trying to install multiple LLVM versions simultaneously |
| sys-devel/clang-common | no | dep of clang | any | |
| sys-devel/llvm-common | no | dep of LLVM | any | |
| sys-devel/llvmgold | no | circ pdep of LLVM | any | just a symlink to the newest version for binutils' ar & nm |
| Runtime packages | ||||
| sys-devel/clang-runtime | by fullver | pdep of LLVM | exact match | |
| sys-libs/compiler-rt | by fullver | dep of clang-runtime | exact match | strictly speaking, does not require exact match to clang version but needs to be installed in path containing fullver |
| sys-libs/compiler-rt-sanitizers | ||||
| sys-libs/libcxx | no | dep of clang-runtime | any | |
| sys-libs/libcxxabi | no | dep of clang-runtime | any | |
| sys-libs/libomp | no | dep of clang-runtime | any | |
| sys-libs/llvm-libunwind | no | dep of clang-runtime | any | |
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