rust/src/test/compile-fail/trivial_casts.rs

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2015-03-23 04:28:57 +00:00
// 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.
// Test the trivial_cast and trivial_numeric_cast lints. For each error we also
// check that the cast can be done using just coercion.
#![deny(trivial_cast, trivial_numeric_cast)]
trait Foo {
fn foo(&self) {}
}
pub struct Bar;
impl Foo for Bar {}
pub fn main() {
// Numeric
let _ = 42_i32 as i32; //~ ERROR trivial numeric cast: `i32` as `i32`
let _: i32 = 42_i32;
let _ = 42_u8 as u8; //~ ERROR trivial numeric cast: `u8` as `u8`
let _: u8 = 42_u8;
// & to * pointers
let x: &u32 = &42;
let _ = x as *const u32; //~ERROR trivial cast: `&u32` as `*const u32`
let _: *const u32 = x;
let x: &mut u32 = &mut 42;
let _ = x as *mut u32; //~ERROR trivial cast: `&mut u32` as `*mut u32`
let _: *mut u32 = x;
// unsize array
let x: &[u32; 3] = &[42, 43, 44];
let _ = x as &[u32]; //~ERROR trivial cast: `&[u32; 3]` as `&[u32]`
let _ = x as *const [u32]; //~ERROR trivial cast: `&[u32; 3]` as `*const [u32]`
let _: &[u32] = x;
let _: *const [u32] = x;
let x: &mut [u32; 3] = &mut [42, 43, 44];
let _ = x as &mut [u32]; //~ERROR trivial cast: `&mut [u32; 3]` as `&mut [u32]`
let _ = x as *mut [u32]; //~ERROR trivial cast: `&mut [u32; 3]` as `*mut [u32]`
let _: &mut [u32] = x;
let _: *mut [u32] = x;
let x: Box<[u32; 3]> = Box::new([42, 43, 44]);
let _ = x as Box<[u32]>; //~ERROR trivial cast: `Box<[u32; 3]>` as `Box<[u32]>`
let x: Box<[u32; 3]> = Box::new([42, 43, 44]);
let _: Box<[u32]> = x;
// unsize trait
let x: &Bar = &Bar;
let _ = x as &Foo; //~ERROR trivial cast: `&Bar` as `&Foo`
let _ = x as *const Foo; //~ERROR trivial cast: `&Bar` as `*const Foo`
let _: &Foo = x;
let _: *const Foo = x;
let x: &mut Bar = &mut Bar;
let _ = x as &mut Foo; //~ERROR trivial cast: `&mut Bar` as `&mut Foo`
let _ = x as *mut Foo; //~ERROR trivial cast: `&mut Bar` as `*mut Foo`
let _: &mut Foo = x;
let _: *mut Foo = x;
let x: Box<Bar> = Box::new(Bar);
let _ = x as Box<Foo>; //~ERROR trivial cast: `Box<Bar>` as `Box<Foo>`
let x: Box<Bar> = Box::new(Bar);
let _: Box<Foo> = x;
// functions
fn baz(_x: i32) {}
let _ = &baz as &Fn(i32); //~ERROR trivial cast: `&fn(i32) {main::baz}` as `&core::ops::Fn(i32)`
let _: &Fn(i32) = &baz;
let x = |_x: i32| {};
let _ = &x as &Fn(i32); //~ERROR trivial cast
let _: &Fn(i32) = &x;
}
// subtyping
pub fn test_subtyping<'a, 'b: 'a>(a: &'a Bar, b: &'b Bar) {
let _ = a as &'a Bar; //~ERROR trivial cast
let _: &'a Bar = a;
let _ = b as &'a Bar; //~ERROR trivial cast
let _: &'a Bar = b;
let _ = b as &'b Bar; //~ERROR trivial cast
let _: &'b Bar = b;
}