[Bug c/20709] strict aliasing warning with float pointer pointing to int pointer

[segher at kernel dot crashing dot org]

------- Additional Comments From segher at kernel dot crashing dot org  
2005-04-05 23:32 -------
Subject: Re:  strict aliasing warning with float pointer pointing to int pointer

> Aka this is valid and defined (even though we warn):
> float a(float b)
> {
>   int i;
>   *(float*)&i = b;
>   return *(float*)&i;
> }

Here, you access the object 'i' of type int, as an object of type
float.  This is not allowed; see 6.5/7.

Perhaps you meant something like:


int a;

float *f(void)
{
        return (float *)&a;
}

int g(void)
{
        return *(int *)f();
}


which is fine, but we indeed warn.

Note it doesn't matter for the validity of this code that float
fits in the same object as int; it is important that float * can
represent the address of an int, though (6.3.2.3/7).



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20709