Re: Invalid compilation without -fno-strict-aliasing

[Horst von Brand]

Falk Hueffner <[e-mail]> said:
> Horst von Brand <[e-mail]> writes:
> > Jean Tourrilhes <[e-mail]> said:
> > > 	if((stream + event_len) < ends) {
> > > 		iwe->len = event_len;
> > > 		memcpy(stream, (char *) iwe, event_len);
> > > 		stream += event_len;
> > > 	}
> > > 	return stream;
> > > }
> > 
> > The compiler is free to assume char *stream and struct iw_event *iwe
> > point to separate areas of memory, due to strict aliasing.
> 
> The relevant paragraph of the C99 standard is:
> 
> An object shall have its stored value accessed only by an lvalue
> expression that has one of the following types:
[...]
> -- a character type.

(char *) gives you a (pointer to) a character type.

> I can't really spot any lvalue here that might violate this rule.  It
> would be nice if somebody could report a bug with a testcase.

stream and (char *) iwe
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
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