[libcxx-commits] [PATCH] D144363: [libcxx] <experimental/simd> Added simd width functions, simd_size traits and related tests

[Nikolas Klauser via Phabricator via libcxx-commits]

philnik added a comment.

In D144363#4488881 <https://reviews.llvm.org/D144363#4488881>, @Joy12138 wrote:

> @philnik Hi, we have added the SFINAE false test for `simd_size`. But the error messages seem not easy to read. Do you have any suggestions?

I think you did something wrong. You shouldn't need a `.verify.cpp` for SFINAE testing, and looking at the error message the types don't SFINAE away.

Something like

  template <class T, class U, class = void>
  struct check_sfinae : false_type {};
  
  template <class T, class U>
  struct check_sfinae<void_t<ex::simd_size<T, U>>> : true_type {};
  
  static_assert(!check_sfinae<int , ex::native_simd<int>>::value);

should work just fine in a normal `.pass.cpp`. If you get an error, either I did something wrong in the SFINAE test, or the implementation of `ex::simd_size` is wrong (because it doesn't SFINAE away).

I'm pretty sure that variable templates can't SFINAE away.


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