Peter Dimov wrote:
Martin Bonner wrote:
Johan Råde wrote:
I still find it hard to believe that the volatile are needed ;-)
It is not.
If volatile is not present, then you can't instantiate the template with T="volatile float" for example. (Similarly you need the "const" so that you can invoke with T="const float".)
template<class T, class S> T binary_cast( S const & s ) { T t; memcpy( &t, &s, sizeof(T) ); return t; }
So you were talking about T. Sorry. :-) Since binary_cast doesn't appear to be safe for use in generic code, it seems reasonable to assume that a programmer invoking binary_cast<const float> or binary_cast<volatile float> expects a return type of const float or volatile float, respectively. But this is impossible. R-values of type float are never cv-qualified. It doesn't make sense to support such incorrect signatures to be produced (even though it's trivially possible by using remove_cv once to remove the error or twice to remove the potential compiler warning about a cv-qualified float return type.)