CODEWITHSUNDEEP
c++templatesgcctype-traits
topisani
topisani

Reputation: 405

GCC 7 not choosing the correct type trait specialization

I am having some issues with gcc 7.2. I have this type trait

template<typename T>
struct audio_frame_channels {}

template<int N>
struct audio_frame_channels<std::array<float, N>> {
  static constexpr auto value = N;
};

And then i use it like this:

  template<typename T>
  auto redirect(T& buf) ->
  ProcessData<audio_frame_channels<std::remove_reference_t<
                                     decltype(buf[0])>>::value>;

clang 6 has no issue with this, but gcc 7.2 complains that ‘value’ is not a member of ‘top1::audio::audio_frame_channels<std::array<float, 1> >’ Have i gotten something wrong, or is this what you get on experimental compilers?

Edit: Obligatory godbolting:

https://godbolt.org/g/Y1EFYC

Upvotes: 0

Views: 60

Answers (1)

TartanLlama
TartanLlama

Reputation: 65770

The second template parameter for std::array is a std::size_t, not int. You need to change it like so:

template<std::size_t N> //instead of int N
struct audio_frame_channels<std::array<float, N>> {
  static constexpr auto value = N;
};

Upvotes: 1

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