src/test/compile-fail/dst-bad-assign.rs

   1 // Copyright 2014 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 // Forbid assignment into a dynamically sized type.
  12
  13 struct Fat<T: ?Sized> {
  14     f1: isize,
  15     f2: &'static str,
  16     ptr: T
  17 }
  18
  19 #[derive(PartialEq,Eq)]
  20 struct Bar;
  21
  22 #[derive(PartialEq,Eq)]
  23 struct Bar1 {
  24     f: isize
  25 }
  26
  27 trait ToBar {
  28     fn to_bar(&self) -> Bar;
  29     fn to_val(&self) -> isize;
  30 }
  31
  32 impl ToBar for Bar1 {
  33     fn to_bar(&self) -> Bar {
  34         Bar
  35     }
  36     fn to_val(&self) -> isize {
  37         self.f
  38     }
  39 }
  40
  41 pub fn main() {
  42     // Assignment.
  43     let f5: &mut Fat<ToBar> = &mut Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
  44     // FIXME (#22405): Replace `Box::new` with `box` here when/if possible.
  45     let z: Box<ToBar> = Box::new(Bar1 {f: 36});
  46     f5.ptr = Bar1 {f: 36};
  47     //~^ ERROR mismatched types
  48     //~| expected `ToBar`
  49     //~| found `Bar1`
  50     //~| expected trait ToBar
  51     //~| found struct `Bar1`
  52     //~| ERROR the trait `core::marker::Sized` is not implemented for the type `ToBar`
  53 }