src/test/compile-fail/wf-static-method.rs

   1 // Copyright 2015 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 // check that static methods don't get to assume their trait-ref
  12 // is well-formed.
  13 // FIXME(#27579): this is just a bug. However, our checking with
  14 // static inherent methods isn't quite working - need to
  15 // fix that before removing the check.
  16
  17 trait Foo<'a, 'b, T>: Sized {
  18     fn make_me() -> Self { loop {} }
  19     fn static_evil(u: &'b u32) -> &'a u32;
  20 }
  21
  22 struct Evil<'a, 'b: 'a>(Option<&'a &'b ()>);
  23
  24 impl<'a, 'b> Foo<'a, 'b, Evil<'a, 'b>> for () {
  25     fn make_me() -> Self { }
  26     fn static_evil(u: &'b u32) -> &'a u32 {
  27         u //~ ERROR E0312
  28     }
  29 }
  30
  31 struct IndirectEvil<'a, 'b: 'a>(Option<&'a &'b ()>);
  32
  33 impl<'a, 'b> Foo<'a, 'b, ()> for IndirectEvil<'a, 'b> {
  34     fn make_me() -> Self { IndirectEvil(None) }
  35     fn static_evil(u: &'b u32) -> &'a u32 {
  36         let me = Self::make_me(); //~ ERROR lifetime bound not satisfied
  37         loop {} // (`me` could be used for the lifetime transmute).
  38     }
  39 }
  40
  41 impl<'a, 'b> Evil<'a, 'b> {
  42     fn inherent_evil(u: &'b u32) -> &'a u32 {
  43         u //~ ERROR E0312
  44     }
  45 }
  46
  47 // while static methods don't get to *assume* this, we still
  48 // *check* that they hold.
  49
  50 fn evil<'a, 'b>(b: &'b u32) -> &'a u32 {
  51     <()>::static_evil(b) //~ ERROR cannot infer an appropriate lifetime
  52 }
  53
  54 fn indirect_evil<'a, 'b>(b: &'b u32) -> &'a u32 {
  55     <IndirectEvil>::static_evil(b)
  56     //~^ ERROR cannot infer an appropriate lifetime
  57 }
  58
  59 fn inherent_evil<'a, 'b>(b: &'b u32) -> &'a u32 {
  60     <Evil>::inherent_evil(b) // bug? shouldn't this be an error
  61 }
  62
  63
  64 fn main() {}