https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67541
--- Comment #2 from Jamie Bayne <jamiebayne at hotmail dot com> --- Ah, so it's fixed in trunk. Thanks for the info. RE the warnings making sense: floating-point promotions may not lose data, but they do have an associated runtime cost (about equivalent to an add on recent Intel architectures), which can be important for code optimisation.
