src/librustc_error_codes/error_codes/E0436.md

   1 The functional record update syntax is only allowed for structs. (Struct-like
   2 enum variants don't qualify, for example.)
   3
   4 Erroneous code example:
   5
   6 ```compile_fail,E0436
   7 enum PublicationFrequency {
   8     Weekly,
   9     SemiMonthly { days: (u8, u8), annual_special: bool },
  10 }
  11
  12 fn one_up_competitor(competitor_frequency: PublicationFrequency)
  13                      -> PublicationFrequency {
  14     match competitor_frequency {
  15         PublicationFrequency::Weekly => PublicationFrequency::SemiMonthly {
  16             days: (1, 15), annual_special: false
  17         },
  18         c @ PublicationFrequency::SemiMonthly{ .. } =>
  19             PublicationFrequency::SemiMonthly {
  20                 annual_special: true, ..c // error: functional record update
  21                                           //        syntax requires a struct
  22         }
  23     }
  24 }
  25 ```
  26
  27 Rewrite the expression without functional record update syntax:
  28
  29 ```
  30 enum PublicationFrequency {
  31     Weekly,
  32     SemiMonthly { days: (u8, u8), annual_special: bool },
  33 }
  34
  35 fn one_up_competitor(competitor_frequency: PublicationFrequency)
  36                      -> PublicationFrequency {
  37     match competitor_frequency {
  38         PublicationFrequency::Weekly => PublicationFrequency::SemiMonthly {
  39             days: (1, 15), annual_special: false
  40         },
  41         PublicationFrequency::SemiMonthly{ days, .. } =>
  42             PublicationFrequency::SemiMonthly {
  43                 days, annual_special: true // ok!
  44         }
  45     }
  46 }
  47 ```