[Bug c/50459] alignof doesn't work on plain old constant, works with expressions containing it

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50459

--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> ---
Creating a function definitely makes sense, I should have done it when I
touched the default_conversion calls. Do you think your function could also
handle the call to default_conversion (with the tests that protect it)?