Internal compiler error passing an iterator as a parameter.

[dradtke]

While practicing my Rust skills by writing a version of GNU cat, I ran into an error that told me to report the results here. The file and the error are included in this gist:

https://gist.github.com/dradtke/7458284

The error only occurs when I try to have cat_files accept an Iterator. If I refactor the code so that it accepts a borrowed pointer to an owned vector of owned strings, then it works.

[alexcrichton]

What version of the compiler were you running this with? If you updated to the most recent version of master, I think that you'll probably see a better error (not certain, just a guess from looking at the program)

[huonw]

With rustc 0.9-pre (825b127 2013-11-12 18:56:13 -0800), I see

10467.rs:5:4: 5:13 error: internal compiler error: Cannot relate bound region: ReLateBound(6, BrNamed(syntax::ast::DefId{crate: 0, node: 20}, self)) <= ReInfer(70)
This message reflects a bug in the Rust compiler. 
We would appreciate a bug report: https://github.com/mozilla/rust/wiki/HOWTO-submit-a-Rust-bug-report
10467.rs:5     cat_files(&args.iter().skip(1));
               ^~~~~~~~~
task 'rustc' failed at 'explicit failure', /home/huon/rust/src/libsyntax/diagnostic.rs:75
task '<main>' failed at 'explicit failure', /home/huon/rust/src/librustc/lib.rs:396

when running on the reduced

fn cat_files<'self, T: Iterator<&'self ~str>>(_: &T) {}

fn main() {
    let args = [~"foo"];
    cat_files(&args.iter().skip(1));
}

It's the same error message as #10391, but appears to be a possibly different cause.

[nikomatsakis]

cc me. I've been negligent and not looked at #10391 yet, I'll see if I can peel off some time today to look at both of these.

[nikomatsakis]

This is in fact a dup of #5121

[nikomatsakis]

In particular we don't (yet) support a function like:

fn cat_files<'self, T: Iterator<&'self ~str>>(_: &T) {}

because 'self appears within the trait bound for T.