Problems with PR 21210

[Gabriel Dos Reis]

Zack Weinberg <zack@codesourcery.com> writes:

| > This also depends on somebody not myself doing a not-insubstantial
| > amount of core compiler work to make it happen; and somebody else
| > jimmying the libstdc++ headers to match, presumably a lesser task.
| 
| I gotta wonder how much of the way there it would get us if we could
| write
| 
|   template <typename T> class complex;
|   template <>
|   typedef _Complex double complex<double>;

If we do that, we mutate C++ because we would have now introduced an
implicit conversion of a std:complex<double> to its real part, where
it did not exist before.

-- Gaby