compiler/rustc_error_codes/src/error_codes/E0436.md

   1 The functional record update syntax was used on something other than a struct.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0436
   6 enum PublicationFrequency {
   7     Weekly,
   8     SemiMonthly { days: (u8, u8), annual_special: bool },
   9 }
  10
  11 fn one_up_competitor(competitor_frequency: PublicationFrequency)
  12                      -> PublicationFrequency {
  13     match competitor_frequency {
  14         PublicationFrequency::Weekly => PublicationFrequency::SemiMonthly {
  15             days: (1, 15), annual_special: false
  16         },
  17         c @ PublicationFrequency::SemiMonthly{ .. } =>
  18             PublicationFrequency::SemiMonthly {
  19                 annual_special: true, ..c // error: functional record update
  20                                           //        syntax requires a struct
  21         }
  22     }
  23 }
  24 ```
  25
  26 The functional record update syntax is only allowed for structs (struct-like
  27 enum variants don't qualify, for example). To fix the previous code, rewrite the
  28 expression without functional record update syntax:
  29
  30 ```
  31 enum PublicationFrequency {
  32     Weekly,
  33     SemiMonthly { days: (u8, u8), annual_special: bool },
  34 }
  35
  36 fn one_up_competitor(competitor_frequency: PublicationFrequency)
  37                      -> PublicationFrequency {
  38     match competitor_frequency {
  39         PublicationFrequency::Weekly => PublicationFrequency::SemiMonthly {
  40             days: (1, 15), annual_special: false
  41         },
  42         PublicationFrequency::SemiMonthly{ days, .. } =>
  43             PublicationFrequency::SemiMonthly {
  44                 days, annual_special: true // ok!
  45         }
  46     }
  47 }
  48 ```