Pass channel argument to cargo as is

src/cli.rs

@@ -1,17 +1,15 @@
 use std::{env, path::PathBuf};
 
-use rustc_version::Channel;
-
 use crate::Target;
 use crate::cargo::Subcommand;
 use crate::errors::Result;
-use crate::rustc::{ChannelExt, TargetList};
+use crate::rustc::TargetList;
 
 #[derive(Debug)]
 pub struct Args {
     pub all: Vec<String>,
     pub subcommand: Option<Subcommand>,
-    pub channel: Option<Channel>,
+    pub channel: Option<String>,
     pub target: Option<Target>,
     pub target_dir: Option<PathBuf>,
 }
@@ -26,8 +24,8 @@ pub fn parse(target_list: &TargetList) -> Result<Args> {
     {
         let mut args = env::args().skip(1);
         while let Some(arg) = args.next() {
-            if arg.starts_with("+") {
-                channel = Some(Channel::from_str(&arg[1..])?);
+            if let ("+", ch) = arg.split_at(1) {
+                channel = Some(ch.to_string());
             } else if arg == "--target" {
                 all.push(arg);
                 if let Some(t) = args.next() {

src/errors.rs

@@ -7,11 +7,4 @@ error_chain! {
     Io(std::io::Error);
     Which(which::Error);
   }
-
-  errors {
-    InvalidChannelName(channel: String) {
-      description("invalid channel name")
-      display("invalid channel name: '{}'", channel)
-    }
-  }
 }

src/main.rs

@@ -20,7 +20,7 @@ use toml::{Value, value::Table};
 
 use self::cargo::{Root, Subcommand};
 use self::errors::*;
-use self::rustc::{ChannelExt, TargetList, VersionMetaExt};
+use self::rustc::{TargetList, VersionMetaExt};
 
 #[allow(non_camel_case_types)]
 #[derive(Debug, Clone, PartialEq)]
@@ -232,7 +232,7 @@ fn run() -> Result<ExitStatus> {
             let default_toolchain = sysroot.file_name().and_then(|file_name| file_name.to_str())
                 .ok_or("couldn't get toolchain name")?;
             let toolchain = if let Some(channel) = args.channel {
-                [channel.to_string()].iter().map(|c| c.as_str()).chain(
+                [channel].iter().map(|c| c.as_str()).chain(
                     default_toolchain.splitn(2, '-').skip(1)
                 )
                     .collect::<Vec<_>>()

src/rustc.rs

@@ -1,7 +1,7 @@
 use std::path::PathBuf;
 use std::process::Command;
 
-use rustc_version::{Channel, Version, VersionMeta};
+use rustc_version::{Version, VersionMeta};
 
 use crate::{Host, Target};
 use crate::errors::*;
@@ -38,33 +38,6 @@ impl VersionMetaExt for VersionMeta {
     }
 }
 
-pub(crate) trait ChannelExt {
-    fn from_str(chan: &str) -> Result<Channel>;
-    fn to_string(&self) -> String;
-}
-
-impl ChannelExt for Channel {
-    fn from_str(chan: &str) -> Result<Channel> {
-        Ok(match chan {
-            "stable" => Channel::Stable,
-            "nightly" => Channel::Nightly,
-            "dev" => Channel::Dev,
-            "beta" => Channel::Beta,
-            _ => return Err(
-                ErrorKind::InvalidChannelName(chan.to_string()).into()
-            ),
-        })
-    }
-    fn to_string(&self) -> String {
-        match self {
-            Channel::Stable => "stable",
-            Channel::Nightly => "nightly",
-            Channel::Dev => "dev",
-            Channel::Beta => "beta",
-        }.to_string()
-    }
-}
-
 pub fn target_list(verbose: bool) -> Result<TargetList> {
     Command::new("rustc")
         .args(&["--print", "target-list"])