member offsets (should be distinct):
====================================
i: 0
letter: 1
data: 2

member values:
==============
i: 0
letter: 56
data:

write to m->data[] and use copy ctor (m2's data should be zeros):
=================================================================
m->data[]: 49494949494949494949
m2->data[]: 0000000000

member values (m2's letter should be 56):
=========================================
i: 0
letter: 56
data: