Should std::byte copy-list-initialization fail?

[Jonathan Wakely]

On 13 July 2017 at 18:58, Jeffrey Walton wrote:
> I'm working on Fedora 26 with GCC 7.1.1. I'm testing some C++17 code
> and learning where some of the pain points are.
>
> $ cat test.cxx
> #include <cstddef>
> int main(int argc, char* argv[])
> {
>   std::byte b1 {0x65};
>   std::byte b2 = {0x66};
>   return 0;
> }
>
> test.cxx: In function ‘int main(int, char**)’:
> test.cxx:5:23: error: cannot convert ‘int’ to ‘std::byte’ in initialization
>    std::byte b2 = {0x66};
>                        ^
>
> It seems like there should be enough information for the compiler to
> determine the list argument type and avoid the error (for b2) like in
> the first example (for b1).
>
> Is the copy-list-initialization failure expected?

Yes. You can't initialize a scoped enumeration type with an implicit conversion.

enum class E { };
E e = { 0 };  // error
E e{ 0 }; // ok in C++17, error in C++14