re PR c++/68508 (Internal compiler error with parentheses around return value in C++14 with ASan enabled)
PR c++/68508
* cp-tree.h (cp_ubsan_maybe_instrument_downcast): Add INTYPE argument.
* cp-ubsan.c (cp_ubsan_maybe_instrument_downcast): Likewise. Use
it instead of or in addition to TREE_TYPE (op). Use
is_properly_derived_from, return NULL_TREE if TREE_TYPE (intype) and
TREE_TYPE (type) are the same type minus qualifiers.
* typeck.c (build_static_cast_1): Adjust callers.