minimum compiler requirements - fast enumeration

A few years ago we declared gcc-4.0 as our minimum supported compiler version.
Does anyone know if gcc-4.0 support for fast enumeration actually works?
If it does, it would be good to start using fast enumeration internally (in gnustep-base for instance).
I'd like to do that as it gives us not only more readable/maintainable code, but also faster code in almost all cases.