src/test/compile-fail/regions-fn-subtyping-return-static.rs

   1 // Copyright 2012 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 // In this fn, the type `F` is a function that takes a reference to a
  12 // struct and returns another reference with the same lifetime.
  13 //
  14 // Meanwhile, the bare fn `foo` takes a reference to a struct with
  15 // *ANY* lifetime and returns a reference with the 'static lifetime.
  16 // This can safely be considered to be an instance of `F` because all
  17 // lifetimes are sublifetimes of 'static.
  18
  19 #![allow(dead_code)]
  20 #![allow(unused_variables)]
  21
  22 struct S;
  23
  24 // Given 'cx, return 'cx
  25 type F = for<'cx> fn(&'cx S) -> &'cx S;
  26 fn want_F(f: F) { }
  27
  28 // Given anything, return 'static
  29 type G = for<'cx> fn(&'cx S) -> &'static S;
  30 fn want_G(f: G) { }
  31
  32 // Should meet both.
  33 fn foo(x: &S) -> &'static S {
  34     panic!()
  35 }
  36
  37 // Should meet both.
  38 fn bar<'a,'b>(x: &'a S) -> &'b S {
  39     panic!()
  40 }
  41
  42 // Meets F, but not G.
  43 fn baz(x: &S) -> &S {
  44     panic!()
  45 }
  46
  47 fn supply_F() {
  48     want_F(foo);
  49
  50     // FIXME(#33684) -- this should be a subtype, but current alg. rejects it incorrectly
  51     want_F(bar); //~ ERROR E0308
  52
  53     want_F(baz);
  54 }
  55
  56 fn supply_G() {
  57     want_G(foo);
  58     want_G(bar);
  59     want_G(baz);
  60     //~^ ERROR mismatched types
  61     //~| expected type `for<'cx> fn(&'cx S) -> &'static S`
  62     //~| found type `for<'r> fn(&'r S) -> &'r S {baz}`
  63     //~| expected concrete lifetime, found bound lifetime parameter 'cx
  64 }
  65
  66 pub fn main() {
  67 }