ICE: Autoderef but type not derefable on fmt!("%?", None)

[ben0x539]

This is probably bad code because there's no way for the compiler to guess the complete type of None, but maybe it could be an explicit failure.

foo.rs:1:17: 1:21 error: internal compiler error: Autoderef but type not derefable: [type error]
foo.rs:1 fn main() { fmt!("%?", None); }
                          ^~~~
note: in expansion of fmt!
foo.rs:1:12: 1:29 note: expansion site

[catamorphism]

Not critical for 0.6; de-milestoning

[pnkfelix]

Nominating for Maturity Milestone 5: "Production Ready"

[graydon]

Bug, yeah. Accepted for production ready.