Hi,

some idea of what is behind this error

http://www.boost.org/development/tests/develop/developer/output/BenPope%20x86_64%20Ubuntu-boost-bin-v2-libs-thread-test-test_11053-test-clang-linux-3-7~ubsan~c14_libc++-debug-threading-multi.html

==14475==Sanitizer CHECK failed: /home/ben/development/llvm/trunk/llvm/projects/compiler-rt/lib/ubsan/ubsan_init.cc:60 ((UBSAN_MODE_UNKNOWN)) != ((ubsan_mode)) (0, 0)

Vicente