src/test/ui/span/issue28498-reject-passed-to-fn.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Demonstrate that a type param in negative position causes dropck to reject code
  12 // that might indirectly access previously dropped value.
  13 //
  14 // Compare with run-pass/issue28498-ugeh-with-passed-to-fn.rs
  15
  16 #[derive(Debug)]
  17 struct ScribbleOnDrop(String);
  18
  19 impl Drop for ScribbleOnDrop {
  20     fn drop(&mut self) {
  21         self.0 = format!("DROPPED");
  22     }
  23 }
  24
  25 struct Foo<T>(u32, T, Box<for <'r> fn(&'r T) -> String>);
  26
  27 impl<T> Drop for Foo<T> {
  28     fn drop(&mut self) {
  29         // Use of `unsafe_destructor_blind_to_params` is unsound,
  30         // because we pass `T` to the callback in `self.2`
  31         // below, and thus potentially read from borrowed data.
  32         println!("Dropping Foo({}, {})", self.0, (self.2)(&self.1));
  33     }
  34 }
  35
  36 fn callback(s: & &ScribbleOnDrop) -> String { format!("{:?}", s) }
  37
  38 fn main() {
  39     let (last_dropped, foo0);
  40     let (foo1, first_dropped);
  41
  42     last_dropped = ScribbleOnDrop(format!("last"));
  43     first_dropped = ScribbleOnDrop(format!("first"));
  44     foo0 = Foo(0, &last_dropped, Box::new(callback));
  45     //~^ ERROR `last_dropped` does not live long enough
  46     foo1 = Foo(1, &first_dropped, Box::new(callback));
  47     //~^ ERROR `first_dropped` does not live long enough
  48
  49     println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1);
  50 }