[Bug c/87307] Implicit conversion from int to vector works, explicit is an error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87307

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>However when you try to perform explicit conversion, you will gen an error.
Right there is another reason why we don't want to support that is because we
support bitwise conversion between vector types and integer types of the same
size.  For an example:
uint64_t a;
__attribute__((vector_size(sizeof(uint64_t) ) )) uint16_t b = (uint64_t)a;