**The `Error` is now an opaque struct**, which allows for more variants to
be added freely, and the internal representation to change without being
breaking changes.
For inspecting an `Error`, there are several `is_*` methods to check for
certain classes of errors, such as `Error::is_parse()`. The `cause` can
also be inspected, like before. This likely seems like a downgrade, but
more inspection can be added as needed!
The `Error` now knows about more states, which gives much more context
around when a certain error occurs. This is also expressed in the
description and `fmt` messages.
**Most places where a user would provide an error to hyper can now pass
any error type** (`E: Into<Box<std::error::Error>>`). This error is passed
back in relevant places, and can be useful for logging. This should make
it much clearer about what error a user should provide to hyper: any it
feels is relevant!
Closes#1128Closes#1130Closes#1431Closes#1338
BREAKING CHANGE: `Error` is no longer an enum to pattern match over, or
to construct. Code will need to be updated accordingly.
For body streams or `Service`s, inference might be unable to determine
what error type you mean to return. Starting in Rust 1.26, you could
just label that as `!` if you never return an error.
If a request sees an error on a pooled connection before ever writing
any bytes, it will now retry with a new connection.
This can be configured with `Config::retry_canceled_requests(bool)`.
Currently, if the remote closes the connection at the same time that the
pool selects it to use for a new request, the connection may actually
hang. This fix will now more allow the keep-alive read to check the
socket even when the `Conn` think it's busy.
If the connection was closed before the request write happened, returns
back an `Error::Cancel`, letting the user know they could safely retry
it.
Closes#1439
