Convert code to anyhow

The main UI impact is that using the anyhow formatters removes some
custom code at a slight UI change - rather than repeating the err! macro
output around each item in the backtrace, we get it just once (see the
comment in common.rs).

Author: rbtcollins

Cargo.lock

@@ -32,7 +32,6 @@ chrono = "0.4"
 clap = "2"
 download = {path = "download", default-features = false}
 effective-limits = "0.5.2"
-error-chain = "0.12"
 flate2 = "1"
 git-testament = "0.1.4"
 home = {git = "https://github.com/rbtcollins/home", rev = "a243ee2fbee6022c57d56f5aa79aefe194eabe53"}

Cargo.toml

@@ -1,11 +1,10 @@
 [package]
 
-name = "download"
-version = "0.6.9"
+authors = ["Brian Anderson <banderson@mozilla.com>"]
 edition = "2018"
-authors = [ "Brian Anderson <banderson@mozilla.com>" ]
-
 license = "MIT/Apache-2.0"
+name = "download"
+version = "0.6.9"
 
 [features]
 
@@ -17,14 +16,15 @@ reqwest-default-tls = ["reqwest/default-tls"]
 reqwest-rustls-tls = ["reqwest/rustls-tls-native-roots"]
 
 [dependencies]
-error-chain = "0.12"
+anyhow = "1.0.31"
+curl = {version = "0.4.11", optional = true}
+env_proxy = {version = "0.4.1", optional = true}
+lazy_static = {version = "1.0", optional = true}
+reqwest = {version = "0.11", default-features = false, features = ["blocking", "gzip", "socks"], optional = true}
+thiserror = "1.0"
 url = "2.1"
-curl = { version = "0.4.11", optional = true }
-env_proxy = { version = "0.4.1", optional = true }
-lazy_static = { version = "1.0", optional = true }
-reqwest = { version = "0.11", default-features = false, features = ["blocking", "gzip", "socks"], optional = true }
 
 [dev-dependencies]
-hyper = { version = "0.14", default-features = false, features = ["tcp", "server"] }
+hyper = {version = "0.14", default-features = false, features = ["tcp", "server"]}
 tempfile = "3"
-tokio = { version = "1", default-features = false, features = ["sync"] }
+tokio = {version = "1", default-features = false, features = ["sync"]}

download/Cargo.toml

@@ -1,25 +1,20 @@
-#![allow(deprecated)] // because of `Error::description` deprecation in `error_chain`
-use error_chain::error_chain;
+use thiserror::Error;
 
-error_chain! {
-    links { }
-
-    foreign_links {
-        Io(std::io::Error);
-        Reqwest(::reqwest::Error) #[cfg(feature = "reqwest-backend")];
-    }
-
-    errors {
-        HttpStatus(e: u32) {
-            description("http request returned an unsuccessful status code")
-            display("http request returned an unsuccessful status code: {}", e)
-        }
-        FileNotFound {
-            description("file not found")
-        }
-        BackendUnavailable(be: &'static str) {
-            description("download backend unavailable")
-            display("download backend '{}' unavailable", be)
-        }
-    }
+#[derive(Debug, Error)]
+pub enum DownloadError {
+    #[error("http request returned an unsuccessful status code: {0}")]
+    HttpStatus(u32),
+    #[error("file not found")]
+    FileNotFound,
+    #[error("download backend '{0}' unavailable")]
+    BackendUnavailable(&'static str),
+    #[error("{0}")]
+    Message(String),
+    #[error(transparent)]
+    IoError(#[from] std::io::Error),
+    #[cfg(feature = "reqwest-backend")]
+    #[error(transparent)]
+    Reqwest(#[from] ::reqwest::Error),
+    #[error(transparent)]
+    CurlError(#[from] curl::Error),
 }