Add a Sync bounds to errors

CHANGELOG.md

@@ -1,5 +1,7 @@
 # Unreleased
 
+- [Add a `Sync` bound to errors](https://github.com./brson/error-chain/pul/110)
+
 # 0.7.2
 
 - Add `quick_main!` (#88).

src/error_chain.rs

@@ -280,7 +280,7 @@ macro_rules! error_chain_processed {
                       EK: Into<$error_kind_name>;
         }
 
-        impl<T, E> $result_ext_name<T, E> for ::std::result::Result<T, E> where E: ::std::error::Error + Send + 'static {
+        impl<T, E> $result_ext_name<T, E> for ::std::result::Result<T, E> where E: ::std::error::Error + Sync + Send + 'static {
             fn chain_err<F, EK>(self, callback: F) -> ::std::result::Result<T, $error_name>
                 where F: FnOnce() -> EK,
                       EK: Into<$error_kind_name> {
@@ -373,7 +373,7 @@ macro_rules! impl_extract_backtrace {
     ($error_name: ident
      $error_kind_name: ident
      $([$link_error_path: path, $(#[$meta_links: meta])*])*) => {
-        fn extract_backtrace(e: &(::std::error::Error + Send + 'static))
+        fn extract_backtrace(e: &(::std::error::Error + Sync + Send + 'static))
             -> Option<::std::sync::Arc<$crate::Backtrace>> {
             if let Some(e) = e.downcast_ref::<$error_name>() {
                 return e.1.backtrace.clone();

src/lib.rs

@@ -45,7 +45,7 @@
 //! * Conversions between error types are done in an automatic and
 //!   consistent way - `From` conversion behavior is never specified
 //!   explicitly.
-//! * Errors implement Send.
+//! * Errors implement `Sync` and `Send`.
 //! * Errors can carry backtraces.
 //!
 //! Similar to other libraries like [error-type] and [quick-error],
@@ -61,11 +61,11 @@
 //! * Instead of defining the custom `Error` type as an enum, it is a
 //!   struct containing an `ErrorKind` (which defines the
 //!   `description` and `display` methods for the error), an opaque,
-//!   optional, boxed `std::error::Error + Send + 'static` object
+//!   optional, boxed `std::error::Error + Sync + Send + 'static` object
 //!   (which defines the `cause`, and establishes the links in the
 //!   error chain), and a `Backtrace`.
 //! * The macro also defines a `ResultExt` trait that defines a
-//!   `chain_err` method. This method on all `std::error::Error + Send + 'static`
+//!   `chain_err` method. This method on all `std::error::Error + Sync + Send + 'static`
 //!   types extends the error chain by boxing the current
 //!   error into an opaque object and putting it inside a new concrete
 //!   error.
@@ -86,7 +86,7 @@
 //!   requiring an `Into` or `From` conversion; as well as slightly
 //!   more cumbersome to match on errors with another layer of types
 //!   to match.
-//! * Because the error type contains `std::error::Error + Send + 'static` objects,
+//! * Because the error type contains `std::error::Error + Sync + Send + 'static` objects,
 //!   it can't implement `PartialEq` for easy comparisons.
 //!
 //! ## Declaring error types
@@ -261,7 +261,7 @@
 //! ```
 //!
 //! `chain_err` can be called on any `Result` type where the contained
-//! error type implements `std::error::Error + Send + 'static`.  If
+//! error type implements `std::error::Error + Sync + Send + 'static`.  If
 //! the `Result` is an `Err` then `chain_err` evaluates the closure,
 //! which returns *some type that can be converted to `ErrorKind`*,
 //! boxes the original error to store as the cause, then returns a new
@@ -416,7 +416,7 @@ pub fn make_backtrace() -> Option<Arc<Backtrace>> {
 
 /// This trait is implemented on all the errors generated by the `error_chain`
 /// macro.
-pub trait ChainedError: error::Error + Send + 'static {
+pub trait ChainedError: error::Error + Sync + Send + 'static {
     /// Associated kind type.
     type ErrorKind;
 
@@ -440,7 +440,7 @@ pub trait ChainedError: error::Error + Send + 'static {
     /// of the errors from `foreign_links`.
     #[cfg(feature = "backtrace")]
     #[doc(hidden)]
-    fn extract_backtrace(e: &(error::Error + Send + 'static)) -> Option<Arc<Backtrace>>
+    fn extract_backtrace(e: &(error::Error + Sync + Send + 'static)) -> Option<Arc<Backtrace>>
         where Self: Sized;
 }
 
@@ -449,7 +449,7 @@ pub trait ChainedError: error::Error + Send + 'static {
 #[doc(hidden)]
 pub struct State {
     /// Next error in the error chain.
-    pub next_error: Option<Box<error::Error + Send>>,
+    pub next_error: Option<Box<error::Error + Sync + Send>>,
     /// Backtrace for the current error.
     #[cfg(feature = "backtrace")]
     pub backtrace: Option<Arc<Backtrace>>,
@@ -473,7 +473,7 @@ impl Default for State {
 impl State {
     /// Creates a new State type
     #[cfg(feature = "backtrace")]
-    pub fn new<CE: ChainedError>(e: Box<error::Error + Send>) -> State {
+    pub fn new<CE: ChainedError>(e: Box<error::Error + Sync + Send>) -> State {
         let backtrace = CE::extract_backtrace(&*e).or_else(make_backtrace);
         State {
             next_error: Some(e),
@@ -483,7 +483,7 @@ impl State {
 
     /// Creates a new State type
     #[cfg(not(feature = "backtrace"))]
-    pub fn new<CE: ChainedError>(e: Box<error::Error + Send>) -> State {
+    pub fn new<CE: ChainedError>(e: Box<error::Error + Sync + Send>) -> State {
         State { next_error: Some(e) }
     }