Merge #73

73: Move from failure to anyhow r=therealprof a=ZeroErrors

## Changes
- Move from `failure` to `anyhow` for error handling

## Description
As of `failure 0.1.8` it has been deprecated ([rust-lang-deprecated/failure#347](rust-lang-deprecated/failure#347)) in favor of using standard rust errors and it is recommended to do that via libraries such as [`anyhow`](https://github.com/dtolnay/anyhow) or [`thiserror`](https://github.com/dtolnay/thiserror).

I chose to go with `anyhow` as its the simplest to convert over to and also since `cargo-binutils` isn't expected to be used as a library I see no need for more detailed error types (See: [dtolnay/anyhow#comparison-to-thiserror](https://github.com/dtolnay/anyhow#comparison-to-thiserror)).

---

**Note:** `failure` isn't fully removed yet as the `rustc-cfg` dependency uses `failure`. I have opened a PR on that repo to hopefully get that changed (japaric/rustc-cfg#12)

r? @therealprof

Co-authored-by: Zero <nick@zero.dev>

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Changed help output to more closely reflect the help command of `cargo` subcommands
 - Removed `walkdir` dependency by using expected path to tool executable
 - Updated `cargo_metadata 0.9 -> 0.10`
+- Replaced `failure` dependency with [`anyhow`](https://github.com/dtolnay/anyhow)
 
 ## [v0.2.0] - 2020-04-11
 

Cargo.toml

@@ -14,10 +14,10 @@ version = "0.2.0"
 [dependencies]
 cargo_metadata = "0.10"
 clap = "2.33"
-failure = "0.1"
 regex = "1.3"
 rustc-cfg = "0.4"
 rustc-demangle = "0.1"
 rustc_version = "0.2"
 serde = "1.0"
 toml = "0.5"
+anyhow = "1.0"

src/lib.rs

@@ -3,11 +3,11 @@
 use std::io::{self, BufReader, Write};
 use std::path::{Component, Path};
 use std::process::{Command, Stdio};
-use std::{env, str};
+use std::str;
 
+use anyhow::{bail, Result};
 use cargo_metadata::{Artifact, CargoOpt, Message, Metadata, MetadataCommand};
 use clap::{App, AppSettings, Arg};
-use failure::bail;
 use rustc_cfg::Cfg;
 
 pub use tool::Tool;
@@ -36,7 +36,7 @@ fn search<'p>(path: &'p Path, file: &str) -> Option<&'p Path> {
     path.ancestors().find(|dir| dir.join(file).exists())
 }
 
-fn parse<T>(path: &Path) -> Result<T, failure::Error>
+fn parse<T>(path: &Path) -> Result<T>
 where
     T: for<'de> serde::Deserialize<'de>,
 {
@@ -52,7 +52,7 @@ where
 impl Context {
     /* Constructors */
     /// Get a context structure from a built artifact.
-    fn from_artifact(metadata: Metadata, artifact: &Artifact) -> Result<Self, failure::Error> {
+    fn from_artifact(metadata: Metadata, artifact: &Artifact) -> Result<Self> {
         // Currently there is no clean way to get the target triple from cargo so we can only make
         // an approximation, we do this by extracting the target triple from the artifacts path.
         // For more info on the path structure see: https://doc.rust-lang.org/cargo/guide/build-cache.html
@@ -81,7 +81,7 @@ impl Context {
 
     /// Get a context structure from a provided target flag, used when cargo
     /// was not used to build the binary.
-    fn from_flag(metadata: Metadata, target_flag: Option<&str>) -> Result<Self, failure::Error> {
+    fn from_flag(metadata: Metadata, target_flag: Option<&str>) -> Result<Self> {
         let meta = rustc_version::version_meta()?;
         let host = meta.host;
         let host_target_name = host;
@@ -106,8 +106,8 @@ impl Context {
         Self::from_target_name(target_name)
     }
 
-    fn from_target_name(target_name: &str) -> Result<Self, failure::Error> {
-        let cfg = Cfg::of(target_name)?;
+    fn from_target_name(target_name: &str) -> Result<Self> {
+        let cfg = Cfg::of(target_name).map_err(|e| e.compat())?;
 
         Ok(Context {
             cfg,
@@ -167,9 +167,7 @@ impl<'a> BuildType<'a> {
     }
 }
 
-fn determine_artifact(
-    matches: &clap::ArgMatches,
-) -> Result<(Metadata, Option<Artifact>), failure::Error> {
+fn determine_artifact(matches: &clap::ArgMatches) -> Result<(Metadata, Option<Artifact>)> {
     let verbose = matches.is_present("verbose");
     let target_flag = matches.value_of("target");
 
@@ -281,7 +279,7 @@ fn determine_artifact(
     Ok((metadata, wanted_artifact))
 }
 
-pub fn run(tool: Tool, examples: Option<&str>) -> Result<i32, failure::Error> {
+pub fn run(tool: Tool, examples: Option<&str>) -> Result<i32> {
     let name = tool.name();
     let about = format!(
         "Proxy for the `llvm-{}` tool shipped with the Rust toolchain.",

src/rustc.rs

@@ -1,18 +1,18 @@
+use std::env;
 use std::path::PathBuf;
 use std::process::Command;
 
-use failure::Error;
-use std::env;
+use anyhow::Result;
 
-pub fn sysroot() -> Result<String, Error> {
+pub fn sysroot() -> Result<String> {
     let rustc = env::var_os("RUSTC").unwrap_or_else(|| "rustc".into());
     let output = Command::new(rustc).arg("--print").arg("sysroot").output()?;
     // Note: We must trim() to remove the `\n` from the end of stdout
     Ok(String::from_utf8(output.stdout)?.trim().to_owned())
 }
 
 // See: https://github.com/rust-lang/rust/blob/564758c4c329e89722454dd2fbb35f1ac0b8b47c/src/bootstrap/dist.rs#L2334-L2341
-pub fn rustlib() -> Result<PathBuf, Error> {
+pub fn rustlib() -> Result<PathBuf> {
     let sysroot = sysroot()?;
     let mut pathbuf = PathBuf::from(sysroot);
     pathbuf.push("lib");

src/tool.rs

@@ -3,7 +3,7 @@ use std::path::PathBuf;
 use std::process::Command;
 use std::{env, process};
 
-use failure::Error;
+use anyhow::Result;
 
 use crate::rustc::rustlib;
 
@@ -38,11 +38,11 @@ impl Tool {
     pub fn exe(self) -> String {
         match self {
             Tool::Lld => format!("rust-lld{}", EXE_SUFFIX),
-            _ => format!("llvm-{}{}", self.name(), EXE_SUFFIX)
+            _ => format!("llvm-{}{}", self.name(), EXE_SUFFIX),
         }
     }
 
-    pub fn path(self) -> Result<PathBuf, Error> {
+    pub fn path(self) -> Result<PathBuf> {
         let mut path = rustlib()?;
         path.push(self.exe());
         Ok(path)