struct S
{
    char	x[2];
    unsigned	y;
};

constexpr bool func(const S s)
{
    return s.x[0] != 42 || s.x[1] != 0;
}

static_assert(!func({{42, 7}, 0}), "bla");

---

Compiled with -std=c++11 -O on various compilers (http://gcc.godbolt.org/)
starting with 4.7.1 up to 7 I get an ICE:

Example with 5.4:
12 : in constexpr expansion of 'func(S{char [2]{'*', '\007'}, 0u})'
12 : internal compiler error: in cxx_eval_bit_field_ref, at cp/constexpr.c:2090
static_assert(!func({{42, 7}, 0}), "bla");