What's wrong with this inline initialization of std::array?

Consider the following declaration:

#include <array>

struct X
{
    //std::array<bool,3> arr={false,false,false};
    bool brr[3]={false,false,false};
};

As is, it compiles normally by g++ 5.2. But if I uncomment the std::array, I get an error:

test.cpp:5:46: error: array must be initialized with a brace-enclosed initializer
     std::array<bool,3> arr={false,false,false};
                                              ^
test.cpp:5:46: error: too many initializers for ‘std::array<bool, 3u>’

OTOH, this declaration works without problems inside main(). Also, the following initialization does work inside struct X:

std::array<bool,3> arr={{false,false,false}};

Why can't I use the simple initialization with single braces in struct definition?