src/test/run-pass/issue-20055-box-trait.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 // See Issues #20055 and #21695.
  12
  13 // We are checking here that the temporaries `Box<[i8, k]>`, for `k`
  14 // in 1, 2, 3, 4, that are induced by the match expression are
  15 // properly handled, in that only *one* will be initialized by
  16 // whichever arm is run, and subsequently dropped at the end of the
  17 // statement surrounding the `match`.
  18
  19 trait Boo {
  20     fn dummy(&self) { }
  21 }
  22
  23 impl Boo for [i8; 1] { }
  24 impl Boo for [i8; 2] { }
  25 impl Boo for [i8; 3] { }
  26 impl Boo for [i8; 4] { }
  27
  28 pub fn foo(box_1: fn () -> Box<[i8; 1]>,
  29            box_2: fn () -> Box<[i8; 2]>,
  30            box_3: fn () -> Box<[i8; 3]>,
  31            box_4: fn () -> Box<[i8; 4]>,
  32             ) {
  33     println!("Hello World 1");
  34     let _: Box<Boo> = match 3 {
  35         1 => box_1(),
  36         2 => box_2(),
  37         3 => box_3(),
  38         _ => box_4(),
  39     };
  40     println!("Hello World 2");
  41 }
  42
  43 pub fn main() {
  44     fn box_1() -> Box<[i8; 1]> { Box::new( [1; 1] ) }
  45     fn box_2() -> Box<[i8; 2]> { Box::new( [1; 2] ) }
  46     fn box_3() -> Box<[i8; 3]> { Box::new( [1; 3] ) }
  47     fn box_4() -> Box<[i8; 4]> { Box::new( [1; 4] ) }
  48
  49     foo(box_1, box_2, box_3, box_4);
  50 }