------- Comment #9 from pdimov at gmail dot com 2010-05-17 20:12 ------- But the standard says in [basic.types] that "For any trivially copyable type T, if two pointers to T point to distinct T objects obj1 and obj2, where neither obj1 nor obj2 is a base-class subobject, if the underlying bytes (1.7) making up obj1 are copied into obj2,40 obj2 shall subsequently hold the same value as obj1."
"float" is a trivially copyable type. Copying X results in copying the bytes of X::data (because the default copy constructor of a class does a memberwise copy, and the default copy constructor of an array does an elementwise copy). Therefore, the underlying bytes of the object of type float, initialized at x1.data, are copied into x2.data, which then must, if interpreted as a float, hold the same value as the original object. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44164
