Floating point rounding modes: we should restrict them slightly

[Walter Bright]

bearophile wrote:
> An important purpose of a not bug-prone language is remove as many
> undefined situations as possible.

That's right.

> If you add that to D2 specs, can
> the compiler catch at compile time all cases of violations to that
> rule?

Unlikely. But that has to be weighed against the former behavior being 
defined in a useless way.


> D has something for the actions that must be done before the function
> exits, the scope(exit). Can something like that be used to
> automatically avoid undefined rounding situations?

Using an RAII object to do it might be better.