An issue with alias

[Daniel]

Code below compiled with vs2015:

#include <vector>

struct SomeTraits
{
template <class T>
using vec = std::vector<T, std::allocator<T>>;
};

template <class Traits>
struct A
{

typedef typename Traits::vec<int> v1_t; // (1)

using v2_t = typename Traits::vec<int>; // (2)
};

int main()
{
typedef SomeTraits::vec<int> v_t1;
using v_t2 = SomeTraits::vec<int>;

v_t1 v1; // OK
v_t2 v2; // OK

A<SomeTraits> a; // Not OK
}

Instantiating A<SomeTraits> results in "syntax error: '<'" for both (1) and (2).
Is that expected?

Thanks,
Daniel

[Alf P. Steinbach]

Yes.

You have to tell the compiler about dependent names when they're types
(you've done that, added `typename`) and when they're templates (need to
add `template`):

template <class Traits>
struct A
{

typedef typename Traits::template vec<int> v1_t; // (1)
using v2_t = typename Traits::template vec<int>; // (2)
};

Cheers & hth.,

- Alf

[Daniel]

On Wednesday, December 7, 2016 at 7:00:57 PM UTC-5, Alf P. Steinbach wrote:
> You have to tell the compiler about dependent names when they're types
> (you've done that, added `typename`) and when they're templates (need to
> add `template`):

Thanks!
Daniel