http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46488
Joe Orton <jorton at redhat dot com> changed:
What |Removed |Added
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CC| |jorton at redhat dot com
--- Comment #19 from Joe Orton <jorton at redhat dot com> 2010-11-29 11:02:26
UTC ---
(In reply to comment #18)
> Using
>
> #define APR_RING_SENTINEL(hp, elem, link) \
> (struct elem *)((char *)(hp) - APR_OFFSETOF(struct elem, link))
>
> should be safer wrt strict aliasing.
We changed the macro from that to the current definition to avoid strict
aliasing warnings from gcc:
http://svn.apache.org/viewvc?view=revision&revision=662299
Does the cast through a char * not have the desired effect of allowing the
pointer to alias any other pointer regardless of type? That is one of the
exceptions in C99 6.5/par 7.
Why specifically does this result in an C99 aliasing violation anyway? The
pointers to which this macro evaluates are never dereferenced, only compared
for equality.
