ICE when using macro as for loop parameter

[milesrout]

macro_rules! foo {
    () => ()
}

pub fn main () {
    for foo!() in (1..) {
    }
}

error:

error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'fold_mac disabled by default', /home/rustbuild/src/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libsyntax/fold.rs:190


playpen: application terminated with error code 101

version is whatever is considered stable by play.rust-lang.org at 3:30pm UTC+12 13/07/2015, but also for the nightly and beta releases.

[Aatch]

I haven't looked yet, but I assume that this is due to the order in which expansions happen. With the for expansion happening before macro expansions. I'm not familiar enough with the code to know if simply doing macro expansion first is a sensible fix or not.