clang compile error using tuple with a single parameter - c++11

Question

I don't understand why clang will not compile the following code but gcc does. No args or more than one arg to tuple works, a single arg does not.
#include <tuple>
int main(int , char *[])
{
// fails
std::tuple<int> a;
// works
std::tuple<> b;
std::tuple<int,int> c;
return 0;
}
The clang error
$ clang++ -std=c++14 tuple.cpp
In file included from tuple.cpp:1:
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:483:62: error: pack
expansion contains parameter packs '_Elements' and '_UElements' that have different lengths
(1 vs. 0)
return __and_<is_constructible<_Elements, _UElements&&>...>::value;
~~~~~~~~~ ~~~~~~~~~~ ^
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:631:21: note: in
instantiation of function template specialization 'std::_TC<true,
int>::_MoveConstructibleTuple<>' requested here
_MoveConstructibleTuple<_UElements...>()
^
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:636:19: note: while
substituting prior template arguments into non-type template parameter [with _UElements = <>]
constexpr tuple(_UElements&&... __elements)
^~~~~
tuple.cpp:5:21: note: while substituting deduced template arguments into function template 'tuple'
[with _UElements = <>, $1 = (no value)]
std::tuple<int> a;
^
In file included from tuple.cpp:1:
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:489:60: error: pack
expansion contains parameter packs '_UElements' and '_Elements' that have different lengths
(0 vs. 1)
return __and_<is_convertible<_UElements&&, _Elements>...>::value;
~~~~~~~~~~ ~~~~~~~~~ ^
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:633:21: note: in
instantiation of function template specialization 'std::_TC<true,
int>::_ImplicitlyMoveConvertibleTuple<>' requested here
_ImplicitlyMoveConvertibleTuple<_UElements...>()
^
/usr/lib/gcc/x86_64-redhat-linux/6.1.1/../../../../include/c++/6.1.1/tuple:636:19: note: while
substituting prior template arguments into non-type template parameter [with _UElements = <>]
constexpr tuple(_UElements&&... __elements)
^~~~~
tuple.cpp:5:21: note: while substituting deduced template arguments into function template 'tuple'
[with _UElements = <>, $1 = (no value)]
std::tuple<int> a;
^
2 errors generated.