Second sorting was not following strict weak ordering as it does not follow transitivity of equivalence property. If you build llvm with libcxx at head as a standard library with -D_LIBCPP_DEBUG_STRICT_WEAK_ORDERING_CHECK and -D_LIBCPP_ENABLE_DEBUG_MODE, then tests like llvm/test/tools/llvm-readtapi/compare-right-single-inline.test.test will fail I don't have commit rights. Danila Kutenin kudanila@yandex.ru Reviewed By: cishida Differential Revision: https://reviews.llvm.org/D157958