&fn is non-copyable

[nikomatsakis]

This test suggests that &fn is noncopyable. I do not believe this should be the case.

type ErrPrinter = &fn(&str, &str);

fn example_err(prog: &str, arg: &str) {
    io::println(fmt!("%s: %s", prog, arg))
}

fn exit(+print: ErrPrinter, prog: &str, arg: &str) {
    print(prog, arg);
}

struct X {
    mut err: ErrPrinter
}

impl X {
    fn boom() {
        exit(self.err, "prog", "arg");
    }
}

fn main(){
    let val = &X{
        err: example_err,
    };
    val.boom();
}

The test yields:

Running /Users/nmatsakis/versioned/rust-gold/build/x86_64-apple-darwin/stage2/bin/rustc:
/Users/nmatsakis/tmp/foo.rs:17:13: 17:21 error: copying a noncopyable value
/Users/nmatsakis/tmp/foo.rs:17         exit(self.err, "prog", "arg");
                                            ^~~~~~~~
/Users/nmatsakis/tmp/foo.rs:17:13: 17:21 note: function arguments must be copyable
/Users/nmatsakis/tmp/foo.rs:17         exit(self.err, "prog", "arg");

[nikomatsakis]

Careful about &once fn etc.

[catamorphism]

Reproduced with 737e115 (though the error is now "moving out of mutable field", it reflects the same issue).

[nikomatsakis]

This is fixed.