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[rustc.git] / src / test / compile-fail / trivial_casts.rs
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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 the trivial_casts and trivial_numeric_casts lints. For each error we also
12// check that the cast can be done using just coercion.
13
14#![deny(trivial_casts, trivial_numeric_casts)]
15
16trait Foo {
17 fn foo(&self) {}
18}
19
20pub struct Bar;
21
22impl Foo for Bar {}
23
24pub fn main() {
25 // Numeric
26 let _ = 42_i32 as i32; //~ ERROR trivial numeric cast: `i32` as `i32`
27 let _: i32 = 42_i32;
28
29 let _ = 42_u8 as u8; //~ ERROR trivial numeric cast: `u8` as `u8`
30 let _: u8 = 42_u8;
31
32 // & to * pointers
33 let x: &u32 = &42;
34 let _ = x as *const u32; //~ERROR trivial cast: `&u32` as `*const u32`
35 let _: *const u32 = x;
36
37 let x: &mut u32 = &mut 42;
38 let _ = x as *mut u32; //~ERROR trivial cast: `&mut u32` as `*mut u32`
39 let _: *mut u32 = x;
40
41 // unsize array
42 let x: &[u32; 3] = &[42, 43, 44];
43 let _ = x as &[u32]; //~ERROR trivial cast: `&[u32; 3]` as `&[u32]`
44 let _ = x as *const [u32]; //~ERROR trivial cast: `&[u32; 3]` as `*const [u32]`
45 let _: &[u32] = x;
46 let _: *const [u32] = x;
47
48 let x: &mut [u32; 3] = &mut [42, 43, 44];
49 let _ = x as &mut [u32]; //~ERROR trivial cast: `&mut [u32; 3]` as `&mut [u32]`
50 let _ = x as *mut [u32]; //~ERROR trivial cast: `&mut [u32; 3]` as `*mut [u32]`
51 let _: &mut [u32] = x;
52 let _: *mut [u32] = x;
53
54 let x: Box<[u32; 3]> = Box::new([42, 43, 44]);
55 let _ = x as Box<[u32]>; //~ERROR trivial cast: `Box<[u32; 3]>` as `Box<[u32]>`
56 let x: Box<[u32; 3]> = Box::new([42, 43, 44]);
57 let _: Box<[u32]> = x;
58
59 // unsize trait
60 let x: &Bar = &Bar;
61 let _ = x as &Foo; //~ERROR trivial cast: `&Bar` as `&Foo`
62 let _ = x as *const Foo; //~ERROR trivial cast: `&Bar` as `*const Foo`
63 let _: &Foo = x;
64 let _: *const Foo = x;
65
66 let x: &mut Bar = &mut Bar;
67 let _ = x as &mut Foo; //~ERROR trivial cast: `&mut Bar` as `&mut Foo`
68 let _ = x as *mut Foo; //~ERROR trivial cast: `&mut Bar` as `*mut Foo`
69 let _: &mut Foo = x;
70 let _: *mut Foo = x;
71
72 let x: Box<Bar> = Box::new(Bar);
73 let _ = x as Box<Foo>; //~ERROR trivial cast: `Box<Bar>` as `Box<Foo>`
74 let x: Box<Bar> = Box::new(Bar);
75 let _: Box<Foo> = x;
76
77 // functions
78 fn baz(_x: i32) {}
54a0048b 79 let _ = &baz as &Fn(i32); //~ERROR trivial cast: `&fn(i32) {main::baz}` as `&std::ops::Fn(i32)`
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80 let _: &Fn(i32) = &baz;
81 let x = |_x: i32| {};
82 let _ = &x as &Fn(i32); //~ERROR trivial cast
83 let _: &Fn(i32) = &x;
84}
85
86// subtyping
87pub fn test_subtyping<'a, 'b: 'a>(a: &'a Bar, b: &'b Bar) {
88 let _ = a as &'a Bar; //~ERROR trivial cast
89 let _: &'a Bar = a;
90 let _ = b as &'a Bar; //~ERROR trivial cast
91 let _: &'a Bar = b;
92 let _ = b as &'b Bar; //~ERROR trivial cast
93 let _: &'b Bar = b;
94}