| // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| // Various unsuccessful attempts to put the unboxed closure kind |
| // inference into an awkward position that might require fixed point |
| // iteration (basically where inferring the kind of a closure `c` |
| // would require knowing the kind of `c`). I currently believe this is |
| // impossible. |
| |
| fn a() { |
| // This case of recursion wouldn't even require fixed-point |
| // iteration, but it still doesn't work. The weird structure with |
| // the `Option` is to avoid giving any useful hints about the `Fn` |
| // kind via the expected type. |
| let mut factorial: Option<Box<Fn(u32) -> u32>> = None; |
| |
| let f = |x: u32| -> u32 { |
| let g = factorial.as_ref().unwrap(); |
| //~^ ERROR `factorial` does not live long enough |
| if x == 0 {1} else {x * g(x-1)} |
| }; |
| |
| factorial = Some(Box::new(f)); |
| } |
| |
| fn b() { |
| let mut factorial: Option<Box<Fn(u32) -> u32 + 'static>> = None; |
| |
| let f = |x: u32| -> u32 { |
| //~^ ERROR closure may outlive the current function, but it borrows `factorial` |
| let g = factorial.as_ref().unwrap(); |
| if x == 0 {1} else {x * g(x-1)} |
| }; |
| |
| factorial = Some(Box::new(f)); |
| } |
| |
| fn main() { } |