src/test/ui/traits/alias/object-wf.rs

   1 // check-pass
   2
   3 // This test checks that trait objects involving trait aliases are well-formed.
   4
   5 #![feature(trait_alias)]
   6
   7 trait Obj {}
   8
   9 trait _0 = Send + Sync;
  10
  11 // Just auto traits:
  12
  13 trait _1 = _0 + Send + Sync;
  14
  15 use std::marker::Unpin;
  16
  17 fn _f0() {
  18     let _: Box<dyn _0>;
  19     let _: Box<dyn _1>;
  20     let _: Box<dyn Unpin + _1 + Send + Sync>;
  21 }
  22
  23 // Include object safe traits:
  24
  25 fn _f1() {
  26     let _: Box<dyn Obj + _0>;
  27     let _: Box<dyn Obj + _1>;
  28     let _: Box<dyn Obj + _1 + _0>;
  29 }
  30
  31 // And when the object safe trait is in a trait alias:
  32
  33 trait _2 = Obj;
  34
  35 fn _f2() {
  36     let _: Box<dyn _2 + _0>;
  37     let _: Box<dyn _2 + _1>;
  38     let _: Box<dyn _2 + _1 + _0>;
  39 }
  40
  41 // And it should also work when that trait is has auto traits to the right of it.
  42
  43 trait _3 = Obj + Unpin;
  44
  45 fn _f3() {
  46     let _: Box<dyn _3 + _0>;
  47     let _: Box<dyn _3 + _1>;
  48     let _: Box<dyn _3 + _1 + _0>;
  49 }
  50
  51 // Nest the trait deeply:
  52
  53 trait _4 = _3;
  54 trait _5 = _4 + Sync + _0 + Send;
  55 trait _6 = _5 + Send + _1 + Sync;
  56
  57 fn _f4() {
  58     let _: Box<dyn _6 + _0>;
  59     let _: Box<dyn _6 + _1>;
  60     let _: Box<dyn _6 + _1 + _0>;
  61 }
  62
  63 // Just nest the trait alone:
  64
  65 trait _7 = _2;
  66 trait _8 = _7;
  67 trait _9 = _8;
  68
  69 fn _f5() {
  70     let _: Box<dyn _9>;
  71 }
  72
  73 // First bound is auto trait:
  74
  75 trait _10 = Send + Obj;
  76 trait _11 = Obj + Send;
  77 trait _12 = Sync + _11;
  78 trait _13 = Send + _12;
  79
  80 fn f6() {
  81     let _: Box<dyn _10>;
  82     let _: Box<dyn _13>;
  83 }
  84
  85 fn main() {}