src/test/run-pass/trivial_casts.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 // Test that all coercions can actually be done using casts (modulo the lints).
  12
  13 #![allow(trivial_casts, trivial_numeric_casts)]
  14
  15 trait Foo {
  16     fn foo(&self) {}
  17 }
  18
  19 pub struct Bar;
  20
  21 impl Foo for Bar {}
  22
  23 pub fn main() {
  24     // Numeric
  25     let _ = 42_i32 as i32;
  26     let _ = 42_u8 as u8;
  27
  28     // & to * pointers
  29     let x: &u32 = &42;
  30     let _ = x as *const u32;
  31
  32     let x: &mut u32 = &mut 42;
  33     let _ = x as *mut u32;
  34
  35     // unsize array
  36     let x: &[u32; 3] = &[42, 43, 44];
  37     let _ = x as &[u32];
  38     let _ = x as *const [u32];
  39
  40     let x: &mut [u32; 3] = &mut [42, 43, 44];
  41     let _ = x as &mut [u32];
  42     let _ = x as *mut [u32];
  43
  44     let x: Box<[u32; 3]> = Box::new([42, 43, 44]);
  45     let _ = x as Box<[u32]>;
  46
  47     // unsize trait
  48     let x: &Bar = &Bar;
  49     let _ = x as &Foo;
  50     let _ = x as *const Foo;
  51
  52     let x: &mut Bar = &mut Bar;
  53     let _ = x as &mut Foo;
  54     let _ = x as *mut Foo;
  55
  56     let x: Box<Bar> = Box::new(Bar);
  57     let _ = x as Box<Foo>;
  58
  59     // functions
  60     fn baz(_x: i32) {}
  61     let _ = &baz as &Fn(i32);
  62     let x = |_x: i32| {};
  63     let _ = &x as &Fn(i32);
  64 }
  65
  66 // subtyping
  67 pub fn test_subtyping<'a, 'b: 'a>(a: &'a Bar, b: &'b Bar) {
  68     let _ = a as &'a Bar;
  69     let _ = b as &'a Bar;
  70     let _ = b as &'b Bar;
  71 }