src/test/ui/in-band-lifetimes.rs

   1 // run-pass
   2
   3 #![allow(warnings)]
   4 #![feature(in_band_lifetimes)]
   5
   6 fn foo(x: &'x u8) -> &'x u8 { x }
   7 fn foo2(x: &'a u8, y: &u8) -> &'a u8 { x }
   8
   9 fn check_in_band_can_be_late_bound() {
  10     let _: for<'x> fn(&'x u8, &u8) -> &'x u8 = foo2;
  11 }
  12
  13 struct ForInherentNoParams;
  14
  15 impl ForInherentNoParams {
  16     fn foo(x: &'a u32, y: &u32) -> &'a u32 { x }
  17 }
  18
  19 struct X<'a>(&'a u8);
  20
  21 impl<'a> X<'a> {
  22     fn inner(&self) -> &'a u8 {
  23         self.0
  24     }
  25
  26     fn same_lifetime_as_parameter(&mut self, x: &'a u8) {
  27         self.0 = x;
  28     }
  29 }
  30
  31 impl X<'b> {
  32     fn inner_2(&self) -> &'b u8 {
  33         self.0
  34     }
  35
  36     fn reference_already_introduced_in_band_from_method_with_explicit_binders<'a>(
  37         &'b self, x: &'a u32
  38     ) {}
  39 }
  40
  41 struct Y<T>(T);
  42
  43 impl Y<&'a u8> {
  44     fn inner(&self) -> &'a u8 {
  45         self.0
  46     }
  47 }
  48
  49 trait MyTrait<'a> {
  50     fn my_lifetime(&self) -> &'a u8;
  51     fn any_lifetime() -> &'b u8;
  52     fn borrowed_lifetime(&'b self) -> &'b u8;
  53     fn default_impl(&self, x: &'b u32, y: &u32) -> &'b u32 { x }
  54     fn in_band_def_explicit_impl(&self, x: &'b u8);
  55 }
  56
  57 impl MyTrait<'a> for Y<&'a u8> {
  58     fn my_lifetime(&self) -> &'a u8 { self.0 }
  59     fn any_lifetime() -> &'b u8 { &0 }
  60     fn borrowed_lifetime(&'b self) -> &'b u8 { &*self.0 }
  61     fn in_band_def_explicit_impl<'b>(&self, x: &'b u8) {}
  62 }
  63
  64 fn test_hrtb_defined_lifetime_where<F>(_: F) where for<'a> F: Fn(&'a u8) {}
  65 fn test_hrtb_defined_lifetime_polytraitref<F>(_: F) where F: for<'a> Fn(&'a u8) {}
  66
  67 fn reference_in_band_from_locals(x: &'test u32) -> &'test u32 {
  68     let y: &'test u32 = x;
  69     y
  70 }
  71
  72 fn in_generics_in_band<T: MyTrait<'a>>(x: &T) {}
  73 fn where_clause_in_band<T>(x: &T) where T: MyTrait<'a> {}
  74 fn impl_trait_in_band(x: &impl MyTrait<'a>) {}
  75
  76 // Tests around using in-band lifetimes within existential traits.
  77
  78 trait FunkyTrait<'a> { }
  79 impl<'a, T> FunkyTrait<'a> for T { }
  80 fn ret_pos_impl_trait_in_band_outlives(x: &'a u32) -> impl ::std::fmt::Debug + 'a {
  81     x
  82 }
  83 fn ret_pos_impl_trait_in_band_param(x: &'a u32) -> impl FunkyTrait<'a> {
  84     x
  85 }
  86 fn ret_pos_impl_trait_in_band_param_static(x: &'a u32) -> impl FunkyTrait<'static> + 'a {
  87     x
  88 }
  89 fn ret_pos_impl_trait_in_band_param_outlives(x: &'a u32) -> impl FunkyTrait<'a> + 'a {
  90     x
  91 }
  92 fn ret_pos_impl_trait_in_band_higher_ranked(x: &'a u32) -> impl for<'b> FunkyTrait<'b> + 'a {
  93     x
  94 }
  95
  96 fn main() {}