Yes, I did build 1.69 successfully [with thin-lto]. That won't help you, though [as I already gave you all the info].
Getting boost to build with clang-cl has been a long-term process [I've been pushing this for close to 2 years]. It only (mostly) works since [important work, boost 1.69] has been done by Peter Dimov (relatively recent)]. You really should dig
into the archives to see what progress has been made (
https://lists.boost.org/Archives/boost/2018/11/244235.php, but there are many more posts), not all might be perfect yet, we are on
the bleeding edge here. The whole thing of building boost with clang-cl [as clang-cl itself, which is part of the problem, while at the same time MSVC is in significant flux as well] is a WIP (work in progress), so you cannot expect things to be perfect [yet,
but the commitment is there (of all parties involved) and I am sure it will be good at some point in the (near?) future].