[Bug c++/60976] Compilation with G++ 4.9.0 is 2-3 times slower than with 4.8.2

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60976

--- Comment #23 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Giuseppe Ottaviano from comment #22)
> Yes I referred to the trailing return type. Unfortunately it's not trivial
> to test it with our code because alloc_traits.h is not anymore a drop-in
> replacement. Maybe the test code included in this bug is enough? Is r225244
> already included in a GCC release?

No, only on trunk. It depends on the additions in r225242, so to use the new
alloc_traits.h you would only need the new code in
https://gcc.gnu.org/viewcvs/gcc/trunk/libstdc%2B%2B-v3/include/std/type_traits?r1=225242&r2=225241&pathrev=225242
(which could be added to the top of alloc_traits.h just in order to test, if
that's easier).