template< typename T, unsigned int n > struct array { constexpr T at(unsigned int i) const { return i < n ? T() : throw 0; } };
template< int m > struct check { static int get() { return m; } };
int main(int, char*[]) { array< int, 5 > arr; check< arr.at(10) > a; return a::get(); }
produces the following error:
./constexpr_test.cpp: In function ‘int main(int, char**)’: ./constexpr_test.cpp:19:21: in constexpr expansion of ‘arr.array<T, n>::at [with T = int, unsigned int n = 5u](10u)’ ./constexpr_test.cpp:6:36: error: expression ‘<throw-expression>’ is not a constant-expression This is expected. Not ideal, but that's what you currently get from constexpr-capable compilers. Clang isn't much different. ./constexpr_test.cpp:19:26: error: invalid type in declaration before ‘;’ token This is just stupid. ./constexpr_test.cpp:20:12: error: ‘a’ is not a class, namespace, or enumeration This is your own fault. You want a.get(), not a::get(). Or maybe the
On 10.01.2013 15:46, Andrey Semashev wrote: line above was supposed to be a typedef? Sebastian