Consider the following code:

$ cat test.cc
template<int>
struct duration
{
    constexpr duration() : r(0) {}

    template<int TPeriod>
    constexpr duration(duration<TPeriod> x) : r(x.count()) {}

    constexpr int count() { return 0; }

    int r;
};

struct Config {
    duration<1> timeout { duration<2>() };
};

Config make_config()
{
    return {};
}

struct ConfigArray {
    ConfigArray();
    Config all_configs[1];
};

ConfigArray::ConfigArray()
{
}

When trying to compile it with GCC 5.1 or trunk r222403 using the following options:
$ g++ -c -std=c++11 ./test.cc

I get the following error:
./test.cc: In constructor 'ConfigArray::ConfigArray()':
./test.cc:28:26:   in constexpr expansion of 'Config()'
./test.cc:28:26:   in constexpr expansion of 'duration<1>(duration<2>())'
./test.cc:7:58:   in constexpr expansion of 'x.duration<<anonymous> >::count<2>()'
./test.cc:28:26: internal compiler error: in cxx_eval_call_expression, at cp/constexpr.c:1331
 ConfigArray::ConfigArray()
                          ^
0x7eb08e cxx_eval_call_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:1331
0x7ebf0c cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3038
0x7ef0ca cxx_eval_store_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:2651
0x7ec869 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3112
0x7ec052 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3365
0x7ec310 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3229
0x7ec310 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3229
0x7ebf64 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3406
0x7f229e cxx_eval_statement_list
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:2828
0x7ec76c cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3400
0x7eb188 cxx_eval_call_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:1365
0x7ebf0c cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3038
0x7ecc94 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3097
0x7ef0ca cxx_eval_store_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:2651
0x7ec869 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3112
0x7ec052 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3365
0x7ec310 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3229
0x7ec310 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3229
0x7ebf64 cxx_eval_constant_expression
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:3406
0x7f229e cxx_eval_statement_list
        /home/miyuki/gcc/src/gcc/cp/constexpr.c:2828
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.