Format! Padding strange utf-8 characters

[decentninja]

This produces only spaces and does not terminate.

fn main() {
    println!("{:2}", "☃")
}

Output (lots of spaces)

☃                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
^C

I guess that the counting of the padding is incorrect when dealing double with unicode characters.

I run OSX 10.10 Beta x86_64

[bluss]

I'd suspect wraparound and a loop that's trying to count to 2**64-1. Looks like line 760 of libcore/fmt/mod.rs -- .char_len() vs .len()

[kmcallister]

Seems to be fixed.