More rustc/combine lifetime issue

#1
  1. Here is my code:

use combine_language::LanguageEnv;
use combine::stream::easy;
use core::fmt;
use std::fmt::Formatter;
use std::error::Error;
use combine::Parser;
use combine::choice;
use combine::parser::combinator::no_partial;
use combine::parser::char::string;


pub struct Foo<'a> {
    data: Vec<MyParser<'a, String>>,
}

impl <'a> Foo<'a> {

    pub fn new() -> Foo<'a> {
        let data = "1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16"
                .split_whitespace()
                .map(|s: & str| {
                    let t =
                        no_partial(string(s)).map(|s: & str| s.to_string());
                    Box::new(t )  as MyParser<'a, String> } )
                .collect::<Vec<_>>();
        Foo { data }
    }

    pub fn make_parser(&mut self) -> impl Parser<Input=easy::Stream<&'a str>, Output=String, PartialState=()> {
        let t = choice(self.data.as_mut_slice());
        return no_partial(t);
        // return Box::new(no_partial(t));
    }
}

pub type MyParser<'a, T> = Box<Parser<Input=easy::Stream<&'a str>, Output=T, PartialState=()> + 'a>;


#[test]
fn empty () {

}
  1. Here is the error:
   |
30 |         let t = choice(self.data.as_mut_slice());
   |                                  ^^^^^^^^^^^^
   |
note: first, the lifetime cannot outlive the anonymous lifetime #1 defined on the method body at 29:5...

   |
29 | /     pub fn make_parser(&mut self) -> impl Parser<Input=easy::Stream<&'a str>, Output=String, PartialState=()> {
30 | |         let t = choice(self.data.as_mut_slice());
31 | |         return no_partial(t);
32 | |         // return Box::new(no_partial(t));
33 | |     }
   | |_____^
note: ...so that reference does not outlive borrowed content

   |
30 |         let t = choice(self.data.as_mut_slice());
   |                        ^^^^^^^^^
note: but, the lifetime must be valid for the lifetime 'a as defined on the impl at 16:7...

What am I doing wrong here? The .as_mut_slice is on the data field of the struct, so it should live atleast 'a.