Non-deterministic Lifetime Error

lifetime-error-fixed.rs

extern crate graphviz;

use graphviz as dot;
use std::str;

type Nd = uint;
type Ed = (uint, uint);
struct Graph<'a> {
    nodes: Vec<&'a str>,
    edges: Vec<Ed>,
}

impl<'a> dot::Labeller<'a, Nd, Ed> for Graph<'a> {
    fn graph_id(&self) -> dot::Id<'a> {
        dot::Id::new("example3")
    }
    fn node_id(&self, n: &Nd) -> dot::Id {
        dot::Id::new(format!("N{:u}", *n))
    }
    fn node_label<'a>(&'a self, i: &Nd) -> dot::LabelText<'a> {
        dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
    }
}

lifetime-error.rs

extern crate graphviz;

use graphviz as dot;
use std::str;

type Nd = uint;
type Ed = (uint, uint);
struct Graph<'a> {
    nodes: Vec<&'a str>,
    edges: Vec<Ed>,
}

impl<'a> dot::Labeller<'a, Nd, Ed> for Graph<'a> {
    fn graph_id(&self) -> dot::Id<'a> {
        dot::Id::new("example3")
    }
    fn node_id(&self, n: &Nd) -> dot::Id {
        dot::Id::new(format!("N{:u}", *n))
    }
    fn node_label<'a>(&self, i: &Nd) -> dot::LabelText<'a> {
        dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
    }
}

non-deterministic-lifetime-error.txt

Sometimes I get this bad error message:
lifetime-error.rs:21:34: 21:48 error: cannot infer an appropriate lifetime for autoref due to conflicting requirements
lifetime-error.rs:21         dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
                                                      ^~~~~~~~~~~~~~
lifetime-error.rs:20:5: 22:6 note: consider using an explicit lifetime parameter as shown: fn node_label<'a>(&self, i: &Nd) -> dot::LabelText<'a>
lifetime-error.rs:20     fn node_label<'a>(&self, i: &Nd) -> dot::LabelText<'a> {
lifetime-error.rs:21         dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
lifetime-error.rs:22     }
error: aborting due to previous error

Other times I get this good error message:
lifetime-error.rs:21:34: 21:48 error: cannot infer an appropriate lifetime for autoref due to conflicting requirements                
lifetime-error.rs:21         dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
                                                      ^~~~~~~~~~~~~~
lifetime-error.rs:20:5: 22:6 note: consider using an explicit lifetime parameter as shown: fn node_label<'a>(&'a self, i: &Nd) -> dot::LabelText<'a>
lifetime-error.rs:20     fn node_label<'a>(&self, i: &Nd) -> dot::LabelText<'a> {
lifetime-error.rs:21         dot::LabelStr(str::Slice(self.nodes[*i].as_slice()))
lifetime-error.rs:22     }
error: aborting due to previous error

I honestly do not see the difference between the good and the bad error message, and my local diff tool can't see it either. Are you maybe looking at different places?

@tbu-, sorry about that. Fixed now

The difference is lines 5 and 15