OPENMP llvm10 doesn't compile because of a typo that was fixed in llvm11: https://github.com/llvm/llvm-project/commit/ea99c09963488130ec0a61ef39df3fd0fcecad3c#diff-6cdf4fa5bc62fbff781fbaba8e5fd806L289 Probably a good idea to backport the patch.
I'm confused. The stray `<` doesn't appear in the checked out source and in fact that commit has the llvmorg-11.0.0-rc1 tag.
Oh, sorry, it's been a long day. You want this fixed in llvm10.
A commit references this bug: Author: brooks Date: Wed Aug 5 22:14:17 UTC 2020 New revision: 544246 URL: https://svnweb.freebsd.org/changeset/ports/544246 Log: Minor fixes. Unbreak OPENMP in some cases. Fix C++ library selection for some target values. PR: 248384, 248386 Submitted by: Greg V Differential Revision: https://reviews.freebsd.org/D24420 Changes: head/devel/llvm10/Makefile head/devel/llvm10/files/clang/patch-D77776 head/devel/llvm10/files/openmp/ head/devel/llvm10/files/openmp/patch-ea99c09