Function syntax::ext::source_util::expand_include

Important traits for Box<R>

impl<R> Read for Box<R> where
    R: Read + ?Sized, impl<W> Write for Box<W> where
    W: Write + ?Sized, impl<I> Iterator for Box<I> where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

pub fn expand_include<'cx>(
    cx: &'cx mut ExtCtxt, 
    sp: Span, 
    tts: &[TokenTree]
) -> Box<MacResult + 'cx>

include! : parse the given file as an expr This is generally a bad idea because it's going to behave unhygienically.