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[Bug tree-optimization/78035] Inconsistency between address comparison and alias analysis


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78035

--- Comment #6 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 19 Oct 2016, amonakov at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78035
> 
> Alexander Monakov <amonakov at gcc dot gnu.org> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |amonakov at gcc dot gnu.org
> 
> --- Comment #5 from Alexander Monakov <amonakov at gcc dot gnu.org> ---
> Note that for external function symbols from the standard library there's an
> old DR that clarifies that their addresses may compare equal, since the library
> may be implemented in a language other than C. See point c) in
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_078.html

"Not implemented in C" would apply to any extern function pair as the
compiler does not know wheter it's part of a "standard library"
(I think restricting the answer to standard library function is
misguided).

> But that is only for function declarations, I don't know if for object
> declarations it's the same or different. Credit goes to Szabolcs Nagy for
> pointing me to this DR.

Usually it's out of the scope of the C standard but we generally try
to honor ELF possibilities.

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