New experimental LLVM project for validation of LLVM packaging

A few months ago, Serge and I were chatting about validation of the
packaging of the LLVM toolchain in our respective distros
(Fedora & Debian/Ubuntu). While doing so, we noticed that we were facing
the same problems and we were coming with very similar solutions.

So, instead of reinventing a Fedora wheel and a Debian wheel, we created
this project:
https://github.com/opencollab/llvm-toolchain-integration-test-suite/
to verify that packaging of LLVM/Clang/Compiler-rt and other projects is
working as expected. It’s basically a collection of integration tests.

In theory, this new testsuite has to be run outside of the llvm-project
source tree, on installed binaries. Running it is as easy as:

> mkdir _build && cd _build
> cmake -DCLANG_BINARY=/usr/bin/clang ..
> cmake --build .

LLVM toolchain 10.0.1 rc4 uploaded in Debian unstable [1] now uses this
feature (as well as the llvm 11 snapshot packages).
Fedora rawhide package also uses it for validating LLVM 10.0.0.

We are looking for other packagers who would be interested in using and
contributing new tests to this testsuite. And, if it makes sense for the
community, integrate in in the LLVM repo.

Serge & Sylvestre

[1] https://ci.debian.net/packages/l/llvm-toolchain-10/unstable/amd64/ / grep “Expected Passes”