src/test/compile-fail/destructure-trait-ref.rs

   1 // Copyright 2012-2014 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 // The regression test for #15031 to make sure destructuring trait
  12 // reference work properly.
  13
  14 #![feature(box_patterns)]
  15 #![feature(box_syntax)]
  16
  17 trait T { fn foo(&self) {} }
  18 impl T for isize {}
  19
  20 fn main() {
  21     // For an expression of the form:
  22     //
  23     //      let &...&x = &..&SomeTrait;
  24     //
  25     // Say we have n `&` at the left hand and m `&` right hand, then:
  26     // if n < m, we are golden;
  27     // if n == m, it's a derefing non-derefable type error;
  28     // if n > m, it's a type mismatch error.
  29
  30     // n < m
  31     let &x = &(&1isize as &T);
  32     let &x = &&(&1isize as &T);
  33     let &&x = &&(&1isize as &T);
  34
  35     // n == m
  36     let &x = &1isize as &T;      //~ ERROR type `&T` cannot be dereferenced
  37     let &&x = &(&1isize as &T);  //~ ERROR type `&T` cannot be dereferenced
  38     let box x = box 1isize as Box<T>; //~ ERROR `T: std::marker::Sized` is not satisfied
  39
  40     // n > m
  41     let &&x = &1isize as &T;
  42     //~^ ERROR mismatched types
  43     //~| expected `T`
  44     //~| found `&_`
  45     //~| expected trait T
  46     //~| found &-ptr
  47     let &&&x = &(&1isize as &T);
  48     //~^ ERROR mismatched types
  49     //~| expected `T`
  50     //~| found `&_`
  51     //~| expected trait T
  52     //~| found &-ptr
  53     let box box x = box 1isize as Box<T>;
  54     //~^ ERROR mismatched types
  55     //~| expected `T`
  56     //~| found `Box<_>`
  57     //~| expected trait T
  58     //~| found box
  59 }