src/test/ui/type-alias-bounds.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 // Test ignored_generic_bounds lint warning about bounds in type aliases
  12
  13 // must-compile-successfully
  14 #![allow(dead_code)]
  15
  16 use std::rc::Rc;
  17
  18 type SVec<T: Send+Send> = Vec<T>;
  19 //~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
  20 type S2Vec<T> where T: Send = Vec<T>;
  21 //~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]
  22 type VVec<'b, 'a: 'b+'b> = (&'b u32, Vec<&'a i32>);
  23 //~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
  24 type WVec<'b, T: 'b+'b> = (&'b u32, Vec<T>);
  25 //~^ WARN bounds on generic parameters are not enforced in type aliases [type_alias_bounds]
  26 type W2Vec<'b, T> where T: 'b, T: 'b = (&'b u32, Vec<T>);
  27 //~^ WARN where clauses are not enforced in type aliases [type_alias_bounds]
  28
  29 static STATIC : u32 = 0;
  30
  31 fn foo<'a>(y: &'a i32) {
  32     // If any of the bounds above would matter, the code below would be rejected.
  33     // This can be seen when replacing the type aliases above by newtype structs.
  34     // (The type aliases have no unused parameters to make that a valid transformation.)
  35     let mut x : SVec<_> = Vec::new();
  36     x.push(Rc::new(42)); // is not send
  37
  38     let mut x : S2Vec<_> = Vec::new();
  39     x.push(Rc::new(42)); // is not send
  40
  41     let mut x : VVec<'static, 'a> = (&STATIC, Vec::new());
  42     x.1.push(y); // 'a: 'static does not hold
  43
  44     let mut x : WVec<'static, &'a i32> = (&STATIC, Vec::new());
  45     x.1.push(y); // &'a i32: 'static does not hold
  46
  47     let mut x : W2Vec<'static, &'a i32> = (&STATIC, Vec::new());
  48     x.1.push(y); // &'a i32: 'static does not hold
  49 }
  50
  51 // Bounds are not checked either, i.e. the definition is not necessarily well-formed
  52 struct Sendable<T: Send>(T);
  53 type MySendable<T> = Sendable<T>; // no error here!
  54
  55 // However, bounds *are* taken into account when accessing associated types
  56 trait Bound { type Assoc; }
  57 type T1<U: Bound> = U::Assoc; //~ WARN not enforced in type aliases
  58 type T2<U> where U: Bound = U::Assoc;  //~ WARN not enforced in type aliases
  59
  60 // This errors
  61 // type T3<U> = U::Assoc;
  62 // Do this instead
  63 type T4<U> = <U as Bound>::Assoc;
  64
  65 // Make sure the help about associatd types is not shown incorrectly
  66 type T5<U: Bound> = <U as Bound>::Assoc;  //~ WARN not enforced in type aliases
  67 type T6<U: Bound> = ::std::vec::Vec<U>;  //~ WARN not enforced in type aliases
  68
  69 fn main() {}