src/librustc_error_codes/error_codes/E0533.md

   1 An item which isn't a unit struct, a variant, nor a constant has been used as a
   2 match pattern.
   3
   4 Erroneous code example:
   5
   6 ```compile_fail,E0533
   7 struct Tortoise;
   8
   9 impl Tortoise {
  10     fn turtle(&self) -> u32 { 0 }
  11 }
  12
  13 match 0u32 {
  14     Tortoise::turtle => {} // Error!
  15     _ => {}
  16 }
  17 if let Tortoise::turtle = 0u32 {} // Same error!
  18 ```
  19
  20 If you want to match against a value returned by a method, you need to bind the
  21 value first:
  22
  23 ```
  24 struct Tortoise;
  25
  26 impl Tortoise {
  27     fn turtle(&self) -> u32 { 0 }
  28 }
  29
  30 match 0u32 {
  31     x if x == Tortoise.turtle() => {} // Bound into `x` then we compare it!
  32     _ => {}
  33 }
  34 ```