Comparing pointers to functions for constexpr fails with gcc not with clang

[Tadeus Prastowo <tadeus.prastowo@xxxxxxxx>]

Hi!

Using http://godbolt.org, I see that the following program compiles in
any clang version that supports -std=c++14 switch (>= 3.5) but fails
in any GCC version >= 5.1 while compiles in any GCC version <= 4.9.4
that supports -std=c++14 switch (>= 4.8.5):

template<typename T, T v>
struct carrier {
  static constexpr T value = v;
};

template<typename T>
inline constexpr bool nontype_nontemplate_args_eq(T arg1, T arg2) {
  return arg1 == arg2;
}
template<typename T1, typename T2>
inline constexpr bool nontype_nontemplate_args_eq(T1, T2) {
  return false;
}

int fn1() {
  return 2;
}

int fn2() {
  return 17;
}

int main() {
  return carrier<bool, nontype_nontemplate_args_eq(&fn1, &fn2)>::value;
}

Is this GCC bug?

Thanks.

--
Best regards,
Tadeus