rustc: Anonymous lifetimes within structs are refused too rigorously

[Florob]

I have the following code:

#[deriving(Clone)]
pub struct Foo {
    priv f: fn(char, |char|)
}

impl Foo {
    fn bar(&self) {
        ((*self).f)('a', |c: char| { println!("{}", c); });
    }
}

fn bla(c: char, cb: |char|) {
    cb(c);
}

pub fn make_foo() -> Foo {
    Foo {
        f: bla
    }
}

fn main() {
    let a = make_foo();

    a.bar();
}

Which currently produces this error:

test.rs:3:10: 3:29 error: mismatched types: expected `fn(char, |char|)` but found `fn(char, |char|)` (expected concrete lifetime, but found bound lifetime parameter &)
test.rs:3     priv f: fn(char, |char|)
                   ^~~~~~~~~~~~~~~~~~~
note: expected concrete lifetime is lifetime ReInfer(ReVar(middle::ty::RegionVid{id: 22u}))
error: aborting due to previous error

This is apparently caused by the closure passed to the referenced function not having a lifetime.
IMHO this should be perfectly legal, because the struct does not actually reference the closure itself.

[nikomatsakis]

Dup of #10501 -- this was never fixed, but the corresponding check in the code was buggy