[Bug c++/60517] warning/error for taking address of member of a temporary object

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60517

--- Comment #7 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #6)
> (In reply to Marc Glisse from comment #5)
> > I would need a different (middle-end) warning that
> > detects return &local_var,
> 
> To confirm this, I looked at the last dangling reference I debugged,
> recompiled it with -O3 -fkeep-inline-functions, and a grep for "return &" in
> the .optimized dump showed:
>   return &one;
>   return &one;
>   return &D.495451.c_;
> (where "one" is a global variable, but D.495451 is a local variable)
> so even this trivial version of the warning would be useful.

To avoid duplicates, the front-end could just return something else, like NULL,
when it detects this case (I guess the behavior is undefined and we can do
whatever we want, no?).