Error type updates (#258)

Update `isahc::Error` to support taking new variants in a backwards-compatible way, as well as hold more error sources when an error is caused by another.

Note that this is the first 1.0 breaking change to land on `master`. If 0.9 needs a patch fix in the future, we'll have to make a 0.9.x branch for it.

Fixes #182.

src/agent.rs

@@ -8,14 +8,17 @@
 //! Since request executions are driven through futures, the agent also acts as
 //! a specialized task executor for tasks related to requests.
 
-use crate::handler::RequestHandler;
-use crate::task::{UdpWaker, WakerExt};
-use crate::Error;
+use crate::{
+    error::Error,
+    handler::RequestHandler,
+    task::{UdpWaker, WakerExt},
+};
 use crossbeam_utils::sync::WaitGroup;
 use curl::multi::WaitFd;
 use flume::{Receiver, Sender};
 use slab::Slab;
 use std::{
+    io,
     net::UdpSocket,
     sync::Mutex,
     task::Waker,
@@ -54,7 +57,7 @@ impl AgentBuilder {
 
     /// Spawn a new agent using the configuration in this builder and return a
     /// handle for communicating with the agent.
-    pub(crate) fn spawn(&self) -> Result<Handle, Error> {
+    pub(crate) fn spawn(&self) -> io::Result<Handle> {
         let create_start = Instant::now();
 
         // Initialize libcurl, if necessary, on the current thread.

src/body.rs

@@ -10,28 +10,6 @@ use std::{
     task::{Context, Poll},
 };
 
-macro_rules! match_type {
-    {
-        $(
-            <$name:ident as $T:ty> => $branch:expr,
-        )*
-        $defaultName:ident => $defaultBranch:expr,
-    } => {{
-        match () {
-            $(
-                _ if ::std::any::Any::type_id(&$name) == ::std::any::TypeId::of::<$T>() => {
-                    #[allow(unsafe_code)]
-                    let $name: $T = unsafe {
-                        ::std::mem::transmute_copy::<_, $T>(&::std::mem::ManuallyDrop::new($name))
-                    };
-                    $branch
-                }
-            )*
-            _ => $defaultBranch,
-        }
-    }};
-}
-
 /// Contains the body of an HTTP request or response.
 ///
 /// This type is used to encapsulate the underlying stream or region of memory

src/client.rs

@@ -3,13 +3,14 @@
 use crate::{
     agent::{self, AgentBuilder},
     auth::{Authentication, Credentials},
+    body::Body,
     config::internal::{ConfigurableBase, SetOpt},
     config::*,
     default_headers::DefaultHeadersInterceptor,
+    error::{Error, ErrorKind},
     handler::{RequestHandler, ResponseBodyReader},
     headers,
     interceptor::{self, Interceptor, InterceptorObj},
-    Body, Error,
 };
 use futures_lite::{future::block_on, io::AsyncRead, pin};
 use http::{
@@ -343,11 +344,11 @@ impl HttpClientBuilder {
                     self.default_headers.append(key, value);
                 }
                 Err(e) => {
-                    self.error = Some(e.into().into());
+                    self.error = Some(Error::new(ErrorKind::ClientInitialization, e.into()));
                 }
             },
             Err(e) => {
-                self.error = Some(e.into().into());
+                self.error = Some(Error::new(ErrorKind::ClientInitialization, e.into()));
             }
         }
         self
@@ -450,20 +451,22 @@ impl HttpClientBuilder {
 
         #[cfg(not(feature = "cookies"))]
         let inner = Inner {
-            agent: self.agent_builder.spawn()?,
+            agent: self.agent_builder.spawn().map_err(|e| Error::new(ErrorKind::ClientInitialization, e))?,
             defaults: self.defaults,
             interceptors: self.interceptors,
         };
 
         #[cfg(feature = "cookies")]
         let inner = Inner {
-            agent: self.agent_builder.spawn()?,
+            agent: self.agent_builder.spawn().map_err(|e| Error::new(ErrorKind::ClientInitialization, e))?,
             defaults: self.defaults,
             interceptors: self.interceptors,
             cookie_jar: self.cookie_jar,
         };
 
-        Ok(HttpClient { inner: Arc::new(inner) })
+        Ok(HttpClient {
+            inner: Arc::new(inner),
+        })
     }
 }
 
@@ -896,7 +899,10 @@ impl HttpClient {
         builder: http::request::Builder,
         body: Body,
     ) -> ResponseFuture<'_> {
-        ResponseFuture::new(async move { self.send_async_inner(builder.body(body)?).await })
+        ResponseFuture::new(async move {
+            self.send_async_inner(builder.body(body).map_err(Error::from_any)?)
+                .await
+        })
     }
 
     /// Actually send the request. All the public methods go through here.

src/config/mod.rs

@@ -170,7 +170,8 @@ pub trait Configurable: internal::ConfigurableBase {
     /// decode the HTTP response body for known and available compression
     /// algorithms. If the server returns a response with an unknown or
     /// unavailable encoding, Isahc will return an
-    /// [`InvalidContentEncoding`](crate::Error::InvalidContentEncoding) error.
+    /// [`InvalidContentEncoding`](crate::error::ErrorKind::InvalidContentEncoding)
+    /// error.
     ///
     /// If you do not specify a specific value for the
     /// [`Accept-Encoding`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding)