Currently users need to set call using namespace llvm;, with this change it's no longer needed.
Sponsored by <The NetBSD Foundation>
Related review: D29288
If we want to make this namespace aware, I wonder if we shouldn't also be explicitly and use ::llvm::once_flag etc. But in general, LGTM.
LGTM, but I will let other LLVM folks give it the final approval.
The idea of this seems fine as-is, but it should be clang-formatted to fit in 80 columns.
Break line to fit the 80-cols limit.
I'd go with @joerg suggestion though (but you don't need to submit another patch, just go ahead and commit).
Use ::lvm namespace.