[Dune-devel] Dune with Visual Studio 2019 (16.2 Preview 2)

[Jö Fahlke]

Thanks,

looks like they managed to get the built-in comma operator wrong.  Basically
the result of the comma operator should have the same type and value category
as the second argument, but if the second argument is a `char &&` xvalue, in
msvc the result of the comma operator becomes a `char` prvalue.

See https://www.godbolt.org/z/DI0bHQ:
```c++
#include <type_traits>

template<class> struct PrintType;

int main()
{
  using T1 = char &;
  using T2 = char &&;
  using Result = decltype((std::declval<T1>(), std::declval<T2>()));
  //PrintType<decltype(std::declval<T2>())>{};
  //PrintType<Result>{};
  static_assert(std::is_same<Result, T2>::value, "fail");
}
```

Does msvc have an issue tracker?

In addition I guess the test for the comma operator can also be thrown out of
the simd testsuite; its mostly in there to alert me to some simd library
overloading the comma operator in funny ways.

Regards,
Jö.

-- 
Jorrit (Jö) Fahlke, Institute for Computational und Applied Mathematics,
University of Münster, Orleans-Ring 10, D-48149 Münster
Tel: +49 251 83 35146 Fax: +49 251 83 32729

featured product: Debian GNU/Linux - http://www.debian.org
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