src/doc/unstable-book/src/language-features/universal-impl-trait.md

   1 # `universal_impl_trait`
   2
   3 The tracking issue for this feature is: [#34511].
   4
   5 [#34511]: https://github.com/rust-lang/rust/issues/34511
   6
   7 --------------------
   8
   9 The `universal_impl_trait` feature extends the [`conservative_impl_trait`]
  10 feature allowing the `impl Trait` syntax in arguments (universal
  11 quantification).
  12
  13 [`conservative_impl_trait`]: ./language-features/conservative-impl-trait.html
  14
  15 ## Examples
  16
  17 ```rust
  18 #![feature(universal_impl_trait)]
  19 use std::ops::Not;
  20
  21 fn any_zero(values: impl IntoIterator<Item = i32>) -> bool {
  22     for val in values { if val == 0 { return true; } }
  23     false
  24 }
  25
  26 fn main() {
  27     let test1 = -5..;
  28     let test2 = vec![1, 8, 42, -87, 60];
  29     assert!(any_zero(test1));
  30     assert!(bool::not(any_zero(test2)));
  31 }
  32 ```