I was working on a fix for #48739 (https://bugs.llvm.org/show_bug.cgi?id=48739), which is about an assertion failure triggered by PointerToMember. Going by the docs for PointerToMember at https://clang.llvm.org/doxygen/classclang_1_1ento_1_1nonloc_1_1PointerToMember.html#details, the list of CXXBaseSpecifiers is for holding the history of casts applied. However, it seems that the list also holds a list of the base classes of the class whose member we are pointing to. My reasoning is summarised at https://reviews.llvm.org/D95307 on my comment on Jan 26.
Am I missing something or is my analysis right?