tests/ui/single-use-lifetime/fn-types.rs

   1 #![deny(single_use_lifetimes)]
   2 #![allow(dead_code)]
   3 #![allow(unused_variables)]
   4
   5 // Test that we DO warn when lifetime name is used only
   6 // once in a fn argument.
   7
   8 struct Foo {
   9   a: for<'a> fn(&'a u32), //~ ERROR `'a` only used once
  10   b: for<'a> fn(&'a u32, &'a u32), // OK, used twice.
  11   c: for<'a> fn(&'a u32) -> &'a u32, // OK, used twice.
  12   d: for<'a> fn() -> &'a u32, // OK, used only in return type.
  13     //~^ ERROR return type references lifetime `'a`, which is not constrained by the fn input types
  14 }
  15
  16 fn main() { }