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SubjectRe: Invalid compilation without -fno-strict-aliasing
Date
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Falk Hueffner <falk.hueffner@student.uni-tuebingen.de> said:
> Horst von Brand <vonbrand@inf.utfsm.cl> writes:
> > Jean Tourrilhes <jt@bougret.hpl.hp.com> 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
Departamento de Informatica Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria +56 32 654239
Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513
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