On Tue, 2007-11-06 at 07:58 -0800, Ian Lance Taylor wrote:
> Joe Buck <[EMAIL PROTECTED]> writes:
> In particular people really do write code like
> int addr = 0x12345678;
> char* p = (char*)&addr;
> *p = 1;
> and
> int f[2] = { 0x80000000, 0 };
> double d = *(double*)f;
> This is not valid C/C++ code.
What you mean is that it is not strictly conforming C code.
[You cannot say that for C++, there is no notion of strictly
conforming C++ code]
> But since there is quite a lot of it
> out there, the -fno-strict-aliasing rule makes it work correctly.
Yes. This is overkill for me: making that work would disable
too many optimisations for my taste.
BTW: gcc handles these rules very cleverly indeed. I have
played with some code and things like union-ing an unsigned
char array correctly defeat the optimisations. I'm quite
surprised, this is very hard to get right.
--
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net
