middle-end/9725: Invalid dependency determination

[Richard Earnshaw]

> Indeed, I see. I that case (which I never was really aware of), it would
> be very desirable for a compiler to emit a warning on the non-conforming
> access rather than silently generating code that wasn't intended by the
> programmer. I frequently see this sort of constructs used (not so much
> using it myself since over time I came to avoid casts as much as
> possible), and searching existing code for it will be a pain, though I
> will have to do it to prevent further optimizer issues.
> 
> Thanks for pointing this out to me, and also thanks for considering
> making the compiler emit a diagnostic for questionable casts to point at
> cases where the optimizer may generate unintended code.
> 

We do have such a warning:

	-Wstrict-aliasing

Unfortunately, it doesn't seem trigger for your test case. :-(

Now that could be considered to be a bug 

R.