OpenMP project or runtime?

[chapuni]

The same holds true for libcxx, compiler-rt, and libunwind.

False for host bootstrapping.
I suppose RUNTIMES build would be just for convenience.

[RFC] RUNTIMES may be built in-tree and be linked to tools

Abstract The most extreme case in RUNTIMES is libcxx. It affects almost all artifacts under compilation. Assume RUNTIMES as libcxx hereafter. (I know libcxx requires libcxxabi) tools means LLVM tools, like llvm, clang, etc., including their development libraries. Don’t build libcxx in LLVM_ENABLE_RUNTIMES for the host. Configure and build libcxx in-tree. Configure tools assuming in-tree libcxx Build tools with -nostdinc++ and -isystem libcxx Link tools to in-tree libcxx This RFC will ma…

Ideally, each PROJECTS build should check capabilities of the host compiler and should reject if the host compiler wasn’t capable. (OTOH RUNTIMES build may assume just-built clang should be able of building each RUNTIMES)