main.rs

fn main() {
    funvsn(&mut std::io::stdio::stdin().chars());
}

// I'd like to make the function type here as generic as possible. All I really
// care about is getting a character iterator but I have two challenges:
//
//  * this doesn't compile (rust 0.13.0, nightly)
//  * there's a pesky std::io::IoResult in there
fn funvsn<I>(it: I) where I: Iterator<std::io::IoResult<char>> {
    for c in it {
	println!("{}", c);
    }
}

zz_build.txt

> rustc src/main.rs
src/main.rs:93:5: 93:11 error: the trait `core::iter::Iterator<core::result::Result<char,std::io::IoError>>` is not implemented for the type `&mut std::io::Chars<'_,std::io::buffered::BufferedReader<std::io::stdio::StdReader>>`
src/main.rs:93     funvsn(&mut std::io::stdio::stdin().chars());
                   ^~~~~~
src/main.rs:93:5: 93:11 note: the trait `core::iter::Iterator` must be implemented because it is required by `funvsn`
src/main.rs:93     funvsn(&mut std::io::stdio::stdin().chars());
                   ^~~~~~
error: aborting due to previous error