vendor/serde/src/std_error.rs

   1 use crate::lib::{Debug, Display};
   2
   3 /// Either a re-export of std::error::Error or a new identical trait, depending
   4 /// on whether Serde's "std" feature is enabled.
   5 ///
   6 /// Serde's error traits [`serde::ser::Error`] and [`serde::de::Error`] require
   7 /// [`std::error::Error`] as a supertrait, but only when Serde is built with
   8 /// "std" enabled. Data formats that don't care about no\_std support should
   9 /// generally provide their error types with a `std::error::Error` impl
  10 /// directly:
  11 ///
  12 /// ```edition2021
  13 /// #[derive(Debug)]
  14 /// struct MySerError {...}
  15 ///
  16 /// impl serde::ser::Error for MySerError {...}
  17 ///
  18 /// impl std::fmt::Display for MySerError {...}
  19 ///
  20 /// // We don't support no_std!
  21 /// impl std::error::Error for MySerError {}
  22 /// ```
  23 ///
  24 /// Data formats that *do* support no\_std may either have a "std" feature of
  25 /// their own:
  26 ///
  27 /// ```toml
  28 /// [features]
  29 /// std = ["serde/std"]
  30 /// ```
  31 ///
  32 /// ```edition2021
  33 /// #[cfg(feature = "std")]
  34 /// impl std::error::Error for MySerError {}
  35 /// ```
  36 ///
  37 /// ... or else provide the std Error impl unconditionally via Serde's
  38 /// re-export:
  39 ///
  40 /// ```edition2021
  41 /// impl serde::ser::StdError for MySerError {}
  42 /// ```
  43 pub trait Error: Debug + Display {
  44     /// The underlying cause of this error, if any.
  45     fn source(&self) -> Option<&(Error + 'static)> {
  46         None
  47     }
  48 }