Added support for 'Sync' compatible error

CHANGELOG.md

@@ -1,3 +1,6 @@
+# 0.12.5
+- [Added the 'Sync' trait so that errors can propogate across threads (e.g. usage within tokio)](https://github.com/john-sharratt/error-chain)
+
 # 0.12.4
 - [executable bits to support build platform linters](https://github.com/rust-lang-nursery/error-chain/pull/289)
 

Cargo.toml

@@ -1,11 +1,12 @@
 [package]
 name = "error-chain"
-version = "0.12.4" # remember to update html_root_url
+version = "0.12.5" # remember to update html_root_url
 authors = [ "Brian Anderson <[email protected]>",
             "Paul Colomiets <[email protected]>",
             "Colin Kiegel <[email protected]>",
             "Yamakaky <[email protected]>",
-            "Andrew Gauger <[email protected]>"]
+            "Andrew Gauger <[email protected]>",
+            "Johnathan Sharratt <[email protected]>"]
 description = "Yet another error boilerplate library."
 keywords = ["error"]
 categories = ["rust-patterns"]
@@ -17,8 +18,9 @@ readme = "README.md"
 license = "MIT/Apache-2.0"
 
 [features]
-default = ["backtrace", "example_generated"]
+default = ["backtrace", "example_generated", "sync"]
 example_generated = []
+sync = []
 
 [dependencies]
 backtrace = { version = "0.3.3", optional = true }

src/error_chain.rs

@@ -218,7 +218,10 @@ macro_rules! impl_error_chain_processed {
             pub $crate::State,
         );
 
-        impl $crate::ChainedError for $error_name {
+        impl $crate::trait_alias::TraitCheck for $error_name { }
+
+        impl $crate::ChainedError for $error_name
+        {
             type ErrorKind = $error_kind_name;
 
             fn new(kind: $error_kind_name, state: $crate::State) -> $error_name {
@@ -231,7 +234,7 @@ macro_rules! impl_error_chain_processed {
 
             fn with_chain<E, K>(error: E, kind: K)
                 -> Self
-                where E: ::std::error::Error + Send + 'static,
+                where E: $crate::trait_alias::StdError + 'static,
                       K: Into<Self::ErrorKind>
             {
                 Self::with_chain(error, kind)
@@ -273,15 +276,15 @@ macro_rules! impl_error_chain_processed {
             /// Constructs a chained error from another error and a kind, and generates a backtrace.
             pub fn with_chain<E, K>(error: E, kind: K)
                 -> $error_name
-                where E: ::std::error::Error + Send + 'static,
+                where E: $crate::trait_alias::StdError + 'static,
                       K: Into<$error_kind_name>
             {
                 $error_name::with_boxed_chain(Box::new(error), kind)
             }
-
+            
             /// Construct a chained error from another boxed error and a kind, and generates a backtrace
             #[allow(unknown_lints, bare_trait_objects)]
-            pub fn with_boxed_chain<K>(error: Box<::std::error::Error + Send>, kind: K)
+            pub fn with_boxed_chain<K>(error: $crate::trait_alias::BoxError, kind: K)
                 -> $error_name
                 where K: Into<$error_kind_name>
             {
@@ -290,7 +293,7 @@ macro_rules! impl_error_chain_processed {
                     $crate::State::new::<$error_name>(error, ),
                 )
             }
-
+            
             /// Returns the kind of the error.
             pub fn kind(&self) -> &$error_kind_name {
                 &self.0
@@ -426,7 +429,7 @@ macro_rules! impl_error_chain_processed {
                       EK: Into<$error_kind_name>;
         }
 
-        impl<T, E> $result_ext_name<T> for ::std::result::Result<T, E> where E: ::std::error::Error + Send + 'static {
+        impl<T, E> $result_ext_name<T> for ::std::result::Result<T, E> where E: $crate::trait_alias::StdError + 'static {
             fn chain_err<F, EK>(self, callback: F) -> ::std::result::Result<T, $error_name>
                 where F: FnOnce() -> EK,
                       EK: Into<$error_kind_name> {

src/lib.rs

@@ -553,6 +553,8 @@ pub use quick_main::ExitCode;
 mod backtrace;
 #[cfg(feature = "example_generated")]
 pub mod example_generated;
+#[doc(hidden)]
+pub mod trait_alias;
 pub use backtrace::Backtrace;
 #[doc(hidden)]
 pub use backtrace::InternalBacktrace;
@@ -592,7 +594,9 @@ impl<'a> Iterator for Iter<'a> {
 
 /// This trait is implemented on all the errors generated by the `error_chain`
 /// macro.
-pub trait ChainedError: error::Error + Send + 'static {
+pub trait ChainedError: crate::trait_alias::StdError + 'static
+where Self: crate::trait_alias::TraitCheck
+{
     /// Associated kind type.
     type ErrorKind;
 
@@ -605,7 +609,7 @@ pub trait ChainedError: error::Error + Send + 'static {
     fn with_chain<E, K>(error: E, kind: K) -> Self
     where
         Self: Sized,
-        E: ::std::error::Error + Send + 'static,
+        E: crate::trait_alias::StdError + 'static,
         K: Into<Self::ErrorKind>;
 
     /// Returns the kind of the error.
@@ -675,7 +679,7 @@ where
 #[allow(unknown_lints, bare_trait_objects)]
 pub struct State {
     /// Next error in the error chain.
-    pub next_error: Option<Box<error::Error + Send>>,
+    pub next_error: Option<trait_alias::BoxError>,
     /// Backtrace for the current error.
     pub backtrace: InternalBacktrace,
 }
@@ -692,7 +696,7 @@ impl Default for State {
 impl State {
     /// Creates a new State type
     #[allow(unknown_lints, bare_trait_objects)]
-    pub fn new<CE: ChainedError>(e: Box<error::Error + Send>) -> State {
+    pub fn new<CE: ChainedError>(e: trait_alias::BoxError) -> State {
         let backtrace = CE::extract_backtrace(&*e).unwrap_or_else(InternalBacktrace::new);
         State {
             next_error: Some(e),

src/trait_alias.rs

@@ -0,0 +1,23 @@
+#[doc(hidden)]
+#[cfg(feature = "sync")]
+pub trait StdError: std::error::Error + Send + Sync { }
+#[doc(hidden)]
+#[cfg(not(feature = "sync"))]
+pub trait StdError: std::error::Error + Send { }
+#[cfg(feature = "sync")]
+impl<E> StdError for E where E: std::error::Error + Send + Sync { }
+#[cfg(not(feature = "sync"))]
+impl<E> StdError for E where E: std::error::Error + Send { }
+#[doc(hidden)]
+#[cfg(feature = "sync")]
+pub type BoxError = Box<dyn std::error::Error + Send + Sync>;
+#[doc(hidden)]
+#[cfg(not(feature = "sync"))]
+pub type BoxError = Box<dyn std::error::Error + Send>;
+
+#[doc(hidden)]
+#[cfg(feature = "sync")]
+pub trait TraitCheck: Send + Sync { }
+#[doc(hidden)]
+#[cfg(not(feature = "sync"))]
+pub trait TraitCheck: Send { }