[llvm-dev] Proposal: introduce dependency on abseil when building benchmarks

[Matthias Braun via llvm-dev]

> On Sep 30, 2021, at 10:07 AM, Mircea Trofin via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> TL;DR; When either of LLVM_BUILD_BENCHMARKS or LIBCXX_INCLUDE_BENCHMARKS are enabled, as well as for llvm-test-suite, a dependency to abseil would either be auto-downloaded by the build system, or need to be user-specifiable, or provided in the source tree.

FWIW: I'm not a fan of auto-downloading stuff. That's just a sneaky to add a dependency that sure may not give trouble to the users where the auto-download succeeds. But many companies have their build farms isolated from the internet and security people would not be happy if we just download a blob of code from a separate project that can change somewhat unnoticed by users of LLVM.

Can't we copy the thing into the LLVM repository (aka vendoring) like we copied the benchmark library? I feel that things become a different story when we actually add dependencies...

- Matthias