------- Comment #5 from rguenth at gcc dot gnu dot org 2009-11-26 16:39 ------- The frontend code should indeed be able to unconditionally warn for ((union ieee_double_extract *)&(x.d))->s.exp because it can see both the underlying object and the access through the non-conflicting type.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42179