help.rs

use std::hashmap::HashMap;

enum Thing { Foo, Bar }

struct Context<'self> {
    scope: HashMap<&'self str, Thing>,
    parent: &'self Option<Context<'self>>
}

impl<'self> Context<'self> {
    fn get(&self, identifier: &str) -> Option<&'self Thing> {
        match self.scope.find_equiv(&identifier) {
            Some(thing) => Some(thing),
            None => match (*self.parent) {
                Some(parent) => parent.get(identifier),
                None => None
            }
        }
    }
}

fn main() {}

help.rs:12:14: 12:50 error: cannot infer an appropriate lifetime due to conflicting requirements
help.rs:12         match self.scope.find_equiv(&identifier) {
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
help.rs:13:27: 13:39 note: first, the lifetime cannot outlive the call at 13:27...
help.rs:13             Some(thing) => Some(thing),
                                      ^~~~~~~~~~~~
help.rs:13:27: 13:39 note: ...due to the following expression
help.rs:13             Some(thing) => Some(thing),
                                      ^~~~~~~~~~~~
help.rs:12:14: 12:24 note: but, the lifetime must be valid for the expression at 12:14...
help.rs:12         match self.scope.find_equiv(&identifier) {
                         ^~~~~~~~~~
help.rs:12:14: 12:24 note: ...due to the following expression
help.rs:12         match self.scope.find_equiv(&identifier) {
                         ^~~~~~~~~~
error: aborting due to previous error