Function syntax::ext::source_util::expand_file

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

🔬 This is a nightly-only experimental API. (rustc_private)

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

file!(): expands to the current filename */ The filemap (loc.file) contains a bunch more information we could spit out if we wanted.